VFX for TV Series

By: Christine Bunish

Iconic characters, both fictional and historical, and a tale from suspense master Stephen King have come alive on the small screen with help from VFX studios. From creating digital environments, futuristic transports and retro inventions to crafting supernatural beings and otherworldly events, VFX enhance the stories of superheroes, pirates, retail magnates, time travelers, small-town Americans and the world’s most famous vampire. AGENTS OF S.H.I.E.L.D. ABC’s new Marvel’s Agents of S.H.I.E.L.D., Marvel’s first venture in live-action television, features the Avengers storyline and characters coupled with extensive VFX by lead vendor FuseFX (www.fusefx.com). With such iconic characters at the core of the series there are frequent references to their incarnations in the comics and on the big screen — ILM has even shared assets created for the films — so consistency is critical. But FuseFX has been able to create and interpret a number of new elements, which make the world of the agents larger-than-life. The series is shot in Culver City, CA, where show VFX supervisor Mark Kolpack is on-set. FuseFX’s artists work from the company’s Burbank office; their numbers have swelled to deliver the large volume of complex shots, which 22 episodes of Marvel’s Agents of S.H.I.E.L.D. demand. With a highly efficient custom pipeline management system and nearly 60 employees, FuseFX has managed to deliver VFX for the series while continuing VFX work on many other shows and projects, including American Horror Story, Hell on Wheels and Criminal Minds.   “We have staffed up and reallocated resources so we have two independent teams working on different episodes of S.H.I.E.L.D. with creative supervision overlapping,” explains FuseFX CEO/VFX supervisor, David Altenau. The company also upgraded to a 300TB Isilon cluster, which doubled its storage capacity, added render nodes to its render farm, and more workstations and software. The chief software tools are Autodesk 3DS Max, Chaos Group’s V-Ray and The Foundry’s Nuke. One of the signature elements in the show is The Bus, a modified C17 military transport plane outfitted with S.H.I.E.L.D. technology. It acts as the agents’ mobile HQ and can travel anywhere in the world at a moment’s notice. FuseFX contributed significant design input to the plane, building “vertical take off and landing into the design from the pilot, although those capabilities weren’t revealed until Episode 8,” says Altenau. “A very complex rig controls every aspect of the plane: the landing gear, engine transformation, doors opening, lighting — even the wings have flex controls for the animators to sell the weight of this massive aircraft. When the engines are in vertical flight mode, they have several degrees of rotation, which give the jet a lot of maneuvering ability.” For Lola, the classic 1962 Corvette that appears on the show, FuseFX added hover capabilities, turning its wheels to a horizontal position and exposing hidden jet-engine ducts. Once again, FuseFX led the collaborative design process with Kolpack and production for Lola’s undercarriage and jet engines. Sometimes the real Corvette is shown transitioning to its hover mode with Sitni Sati’s FumeFx adding volumetric dust and exhaust, and Side Effects’ Houdini particle effects. Sometimes FuseFX is required to use a fully-digital model of the car, which matches the real vehicle precisely.   On the human side, FuseFX provides robotic leg replacement for Mike Peterson, or Deathlok, and digital doubles for augmenting stunts and performing fully-digital stunts. In a dramatic one-off stunt sequence, two of the main characters jumped out of the back of The Bus with only a single parachute; the sequence included 30 shots and was a combination of a fully-digital environment, digital doubles for wide shots and actors shot on greenscreen with a gimbal rig.   In another one-off shot, the team battles one of the key villains, Ian Quinn, who creates a massive machine that harnesses the exotic substance, gravitonium. The episode culminates with Dr. Franklin Hall falling into and getting consumed by the gravitonium — giving FuseFX the opportunity to help visualize the genesis of one of Marvel’s classic characters, Graviton. One of the keys to doing VFX for TV successfully is “client-VFX chemistry” and constant close communications, Altenau says. “You need to head toward the target as quickly as possible creatively. On features you have the luxury of taking a detour to try something new, but on TV you don’t. Everyone has to be on the same page in terms of creative direction so you can get to the end game on as direct a path as possible. Marvel has been really great at collaboration and working constructively with us to achieve that. We’re very excited to be working on the show. We couldn’t imagine a better series to be involved with.” DRACULA Dracula’s back and he’s never looked so good. In the guise of American entrepreneur Alexander Grayson, the iconic vampire, elegantly played by Jonathan Rhys Meyers, is alive (or undead) and well in Victorian London, surrounded by lush locations and beautiful costumes. Little wonder that the woman who appears to be a reincarnation of his long-dead wife falls under his spell. He can’t escape his blood-soaked past (and present), but NBC’s Dracula draws the line at excessive gore. In fact, its London-based producers, Carnival Films, are the folks behind Downton Abbey. “They bring a Downton aesthetic to the show,” notes the show’s VFX supervisor Kent Johnson, who serves as VFX supervisor/producer at LA’s Stargate Studios (www.stargatestudios.net). “The violence in Dracula is very subtle; they didn’t want it to be in your face.”   The challenges for this new interpretation of Dracula concerned inventing his world, says Johnson. “We had to answer a lot of big questions and determine the visual aesthetic.” He spent six-and-a-half months in pre-pro and production in Budapest, which doubles for Victorian London. He met early on with the producers to discuss some very “high-concept ideas,” including how to visualize the mystic visions of vampire seers and Dracula’s own point of view, which manifests itself when the blood-starved vampire sees people’s pulsing hearts and veins as he walks down the street. But first Stargate had to transform the 400-year old corpse of Dracula into the young and vital Alexander Grayson. “That effect took a great deal of development,” Johnson recalls. “There was a puppet Dracula corpse at the start and Jonathan in make up at the end; using hundreds of photos of the puppet and Jonathan, we constructed a 3D model to transition between the two.” VFX were key in Dracula’s fight to the death with a vampire huntsman on a London rooftop. Stargate created a cityscape from 3D models and matte paintings, which acted as the backdrop for stunt performers and actors rigged on flying harnesses. A CG arrow pierced Dracula’s leg and CG swords were extended from practical hilts to ensure safe combat. “They went to great lengths for an accurate recreation of Victorian-era London,” says Johnson. “The producer had done the two Robert Downey Sherlock Holmes films, so he knew where to go to shoot the architecture of the period. We did a big VFX location shoot in London — I took about 15,000 stills from rooftops and church steeples. A cherry picker took me up in the middle of a bridge over the Thames to get the perfect shot of Big Ben and the Houses of Parliament. And I was 45 feet in the air at dawn over Trafalgar Square.” Johnson’s vast library of stills was used to create photographic matte paintings that were projected onto 3D geometry.   Grayson’s resonator, which generates wireless electricity, went through a lot of creative R&D. “We started with steampunk-esque Tesla coils, but Carnival’s aesthetic kept wanting it to be more subtle so as not to distract from the dialogue and action,” says Johnson.  “This wasn’t Frankenstein’s lab.”   Grayson’s demonstration of the technology elicited “countless discussions” among the creatives. Hundreds of spectators were shown holding clear light bulbs in their hands, illuminated by the wireless power of the resonator. “Because the producers wanted to see the filaments in the bulbs, it was important that they be regular incandescent bulbs,” Johnson explains. “So they ran electrical lines to every bulb and did the effect in camera. Although it took us a great deal of time and labor to paint out the electrical lines to 300 extras holding bulbs in a ballroom, it was still less expensive than hiding wires in clothing and sets. And the lights are so close to people’s faces that they’re part of the lighting for the scene and create a warm glow captured by the camera.” Stargate was also responsible for some organic VFX. When Dracula is infused with Van Helsing’s serum to allow him to stay out in the sunlight, his CG veins appear engorged as the serum flows through his body. But the treatment doesn’t work exactly as hoped and Dracula’s skin begins to redden and burn after more than a few minutes of exposure to the sun.   “The make up department started the process on Jonathan, and we stepped in when his skin blackens, chars and smokes,” says Johnson. “We had hundreds of photos of Jonathan to work with. We used [Autodesk] Maya and [NewTek] LightWave [3D] to get the look in 3D, and integrated it with his moving body with [Imagineer Systems’] Mocha and [Adobe] After Effects. Later, when Dracula feeds and heals, we filmed Jonathan with make up and without, and transitioned between the two to create a sense of the skin growing back as he heals.”   Johnson admits it was “a bit of a challenge to be in Budapest and supervise artists in LA,” but lots of video conferencing with Stargate VFX producer Tyler Foell and remote access to the artists’ work-in-progress helped to close the geographical gap. In the end, Dracula is not really a VFX show, Johnson says. “It’s more love story than supernatural thriller.” MR. SELFRIDGE London-based DNeg TV, the television division of Double Negative Visual Effects (www.dneg.com), completed VFX for Season 2 of Mr. Selfridge, a co-production of ITV Studios and Masterpiece, which is currently being broadcast in the US on Sunday nights on PBS’s Masterpiece.  The second season of the popular show, about the retail empire of the American-born founder of London’s Selfridge’s department store, takes place in 1914. DNeg TV was charged with recreating the exterior of the store and updating the look of Oxford Street, which had changed dramatically since Season 1, set five years earlier. “The exterior is like another character in the show,” says Hayden Jones, VFX supervisor and one of the founders of DNeg TV with Jonathan Privett and Louise Hussey. “It’s such an iconic building that we knew it had to look correct; viewers would know instantly if it wasn’t right.” Exterior shots typically show “the tapestry of life” on Oxford Street, with “people walking down the street, chatting as they go into the store, workers preparing for a royal visit by rolling out the red carpet. All sorts of action takes place outside.”   A small section of the exterior was built as a set on Chatham Docks, says Jones. “It’s one-story high and covers three windows and one set of double doors. We built the other four floors and the other half of the building. Everything beyond the greenscreens on set is all digital — cars, horse-drawn buses, carriages, people, street lamps, buildings,” Jones says. “It’s an amazing challenge.” In the interest of “matching CG down to the millimeter” of the exterior set, DNeg TV did a LIDAR (Light Detection And Ranging) scan of the set to facilitate an accurate digital recreation. “It allowed us to make sure the set extension model fits perfectly to the set,” Jones explains. “It can’t be a millimeter off.” The exterior of Selfridge’s features “so many vertical uprights that it’s very unforgiving to do match moves,” he notes. “One of the joys of working here is our fantastic R&D department, so a lot of our tracking tools are bespoke. They produce excellent results on shots that normally would be extremely difficult to track.” DNeg TV had to recreate different day parts for Oxford Street, too. “Now [World War I] is upon us and they’ve dimmed down lights for blackouts.” In one shot, “the DP left all the lenses wide open for a short depth of field, giving a nice textural feel to the out of focus areas of the image,” says Jones. “We had to match that, even to the model and the optical quality of the lenses. It’s a subtle effect, achieved primarily by using Nuke, but it adds so much.”   Maya is the main animation tool for the show, with rendering done in Pixar’s RenderMan. Once the producers of Mr. Selfridge saw how quickly DNeg TV could turn around shots, Jones found the company advising on new shots for episodes, one of which also ended up in the title sequence. “We went up five stories on the building opposite with the camera then tilted down for a super-high wide shot where Selfridge’s looks almost like the prow of a ship,” Jones says. “We weren’t sure it could be done within the budget, but we were confident in our tracking tools and delivered the shot on-time and on-budget. It looked so great that they decided to put it in the title sequence, too.” Although barely 10 months old, DNeg TV has a host of other credits: all three seasons and the forthcoming season four of the mystery series Death in Paradise for the BBC; a new Sunday-night family drama series for BBC One; a new drama series for Sony/Starz; and a pilot for NBC/Universal. And DNeg TV will be back adding more details and texture to c. 1919 Oxford Street for Season 3 of Mr. Selfridge. UNDER THE DOME The CBS summer 2013 hit, Under The Dome, gave viewers a look at the personal and political dynamics of a small American town that’s suddenly covered by an impermeable, transparent dome, which isolates them from contact and communication with the outside world. Based on the novel by Stephen King (who is an executive producer, along with Steven Spielberg), the series returns this summer — possibly with some explanations of the dome’s secrets, and definitely with more mysteries.   Since the dome plays such a big role in the show, developing its look was a crucial part of the VFX work. “When Episode 5 was filming, I was still creating looks for the dome on my laptop and showing them to the executives,” says Stephan Fleet, executive creative director at Encore (www.encorepost.com) and VFX supervisor for Under The Dome. “We couldn’t see it in every shot or the whole show would be a VFX shot. But when we got close to it we had to know what it looked like, what it felt like when people touched it.” Some properties of the dome were pre-established. “We always knew it would slice through things,” Fleet says. “It had to be hard, not wobbly. It was semi-magical but had to be believable — it couldn’t look like ice or be too supernatural. And it couldn’t be reflective because that would pose huge production issues” for an episodic show. Fleet put up pieces of plastic for the actors to interact with on set but avoided any complicated props that would require a lot of time in post to remove. “For TV, you aim for as little footprint as possible on the set,” he notes. That the dome could slice through things was evident from the start, when one of its edges came down on a farm, cleaving a cow in two.  The first proposal called for a stuffed cow prop, sweetened with VFX blood and gore. When that didn’t work as well as desired, it was ultimately recreated in CG. “And the half-cow became the icon of the show: It’s on T-shirts and posters,” Fleet exclaims.   A truck and plane crash from outside into the dome were also CG. The truck crash was initially planned as a practical effect. “It almost worked, but when we blended in CG enhancements, it read too fake, so we went with 100 percent CG,” he says. Monarch butterflies were a recurring motif. A flock of them first appeared inside the dome wall, fanned out in all their glory. Later in the episode, a nuclear missile failed to breach the dome (the complete destruction on the other side was full CG environment replacement by Encore).  Then, a single monarch reappeared and landed on the dome. The butterfly also played a key role in the season finale. “We didn’t know that the monarchs would be a huge theme in the show” at the outset, says Fleet. “We built about 14 quality butterflies for that opening sequence on the dome wall and a detailed butterfly for the very end of the show. An individual butterfly model is fairly easy to execute, but we needed to use particle simulations to multiply them. It took a lot of math and horsepower to make them realistic.”  Encore also created VFX for the mini dome, which formed around a mysterious egg found in the woods. The mini dome turned white before it exploded and dissolved to dirt — all VFX shots. Encore enhanced the egg itself, which typically appeared as a prop, creating “pink stuff” that crawled up its surface and a caterpillar that transformed into the hero monarch butterfly, which appears to select a leader from the town’s supernaturally gifted young residents. Fleet, and Encore’s other VFX supervisor, Adam Avitabile, opted for practical solutions whenever possible. “I’m a big fan of practical effects,” says Fleet. “We use a process of elimination to determine what will be VFX shots. I’m not a fan of up-selling people.”  For the long-awaited pink falling stars — referenced in the first episode and finally visualized at the end of Season 1 — Encore had few specifics to guide them. The team initially created pink stars that “looked more like fireworks,” Fleet says. Then he and his artists suggested having them shoot up the sides of the dome in otherworldly straight lines — a hauntingly-cool image that everyone loved.   The stars were a mix of particles composited with treetops and other natural elements captured by Fleet with his Canon 5D camera and used as plates. Autodesk 3DS Max was the show’s main 3D software, with Nuke the primary compositing tool and Andersson Technologies’ SynthEyes the tracking software. Encore handled post for the series as well. Fleet notes that creating VFX for TV “gets harder every season because the stakes are raised with every show.” He approaches a series with a sense of restraint, however. “We have an honest dialogue about what I think is feasible and what isn’t. I want shows to look good with quality VFX — I’ve seen too many with too much stuff going on, and the VFX suffer.” SLEEPY HOLLOW Revolutionary War soldier Ichabod Crane has awakened in present-day Sleepy Hollow, but he’s still pursued by The Headless Horseman in Fox’s new hit series that mingles eras, history and mystical practices. Synaptic VFX, which has offices in Burbank and New Orleans (www.synapticvfx.com), provided a wide range of VFX for Season 1, including the villainous Headless Horseman, digital environments and a demonic possession. “For a number of  VFX, my brother Shahen did the concept art,” says Shant Jordan, a 3D artist and compositor who founded Synaptic VFX with Shahen Jordan and Ken Gust. “Synaptic provided a complete solution for the show, from concept to execution.”    Jordan notes that the company’s roots “are in TV and film. In TV we expect to do feature-level VFX for smaller budgets and faster turnarounds. But we can do 300 shots in seven days instead of four months because we have an established pipeline that can be tailored to a show’s needs. The most important part of the process, though, is communication. Without that, even the most refined pipeline falls apart.” Synaptic already had close ties to longtime friend and show VFX supervisor Jason Zimmerman, who worked on-set in North Carolina for the duration of Season 1. “We could ask him questions at any point in the day” as live-action plates were funneled to Synaptic, says Jordan. “It’s what defined the success of the show.” The Headless Horseman, a key recurring player in Sleepy Hollow, was performed by several stuntmen wearing green masks. For his sequences, Synaptic removed his head, replaced it with a bloody stump and painted in the background. In one scene, for which Shahen did the concept art, The Headless Horseman gallops through the woods as the environment catches fire around him, embers flying in the air.   “The challenge for this character is that he’s always moving,” notes Shant Jordan. “He’s riding, swinging an axe or other weapons — there’s a lot of animation. We have tracking markers on his head and around his collar; we put in a CG collar to anchor the neckpiece.” Episode 4 flashed back to the Boston Tea Party, with a Synaptic digital matte painting depicting the harbor and ships. “We used projected matte painting techniques along with 3D geometry to achieve the desired look, just like we do with films,” says Jordan. Reference material helped create authentic geography. For the horrifying demonic possession of a teenage girl, Synaptic replaced her arms with CG limbs and altered her already distorted face. “When the make-up wasn’t scary enough, we built a model of her face, warped it and replaced it,” Jordan explains. Earlier, the company augmented the make-up for Serilda the witch, adding fire and glow under her skin.   Synaptic’s toolset includes LightWave 3D, 3DS Max and Maya, with Nuke and After Effects for compositing and Science D-Visions’ 3DEqualizer for match moving. As Sleepy Hollow heads into its second season, Jordan tells fans to “look for more” VFX as the plot lines of the cliffhanger season finale are explored. By operating with a different paradigm, with “teams of multifaceted artists who understand a sense of urgency,” Synaptic will prepare for Season 2 as it crafts VFX for a “very demanding” Fox pilot, Hieroglyph. BLACK SAILS The new eight-episode Starz series, Black Sails, tells the tale of early 18th-century pirates in what’s now Nassau, The Bahamas, and their quest for gold from the legendary Urca de Lima. Crazy Horse Effects, Inc., in Venice, CA (www.chevfx.com), was one of the lead VFX vendors for Season 1, creating the environments for Nassau and nearby islands. “Production had a clear idea of what they wanted: the shape of the bay and Hog Island (now known as Paradise Island) that protects the bay, the beach with shacks below the fort, the rocky area with shipwrecks,” says Crazy Horse VFX supervisor and creative director Paul Graff. “This wasn’t Pirates of the Caribbean. Starz wanted it to be realistic. Previs from the VFX department and a few sketches from the art department helped direct the look of our work, but our creative team also ran ideas by them. It was a very collaborative process.”   The panoramic view of Nassau and the bay was a big Photoshop matte painting with CG models, created in Maxon Cinema4D, embedded with After Effects. When Graff thought the shot needed real water plates, he flew to The Bahamas to direct a live-action shoot and compile a library of water plates, palm trees and other native vegetation to populate the 3D environments. The series is shot in Capetown, South Africa, where show VFX supervisor Erik Henry was busy on-set. Paul Graff and Crazy Horse VFX executive producer Christina Graff had previously worked with Henry on the award-winning John Adams series. “We got as much for the library as we could — shots of beaches, surf from all angles, water from the perspective of a tall ship and low from a skiff,” he explains. “We still created some CG water with 3DS Max, but CG water tends to look a bit repetitive while real water is infinitely random.” Graff notes that with freeways in close proximity to the Capetown location, it was hard to get the camera any distance from the set. “So whenever there was a shot in the bay looking back at Nassau, we had to patch together images from the set with plates of our own.” Crazy Horse did a roof replacement on a real Capetown farmhouse to change its architecture. The company also built out the big fort from “a bit of raised set with a turret and a few crenellations,” says Christina Graff. The fort was seen in a number of shots: big reveals of the island terrain, crane moves and approached from behind by a character walking up a hillside. A spectacular high-angle view from the fort over the bay showed CG ships, beaches and Hog Island. Paul’s real water plates were combined with water-tank plates that were rotoscoped and painted below the surface to give the look of greater transparency.   Paul Graff observes that many VFX shots were “creative journeys” for the Crazy Horse team and the production. A night shot of Nassau by torchlight evolved to versions overlooking the bay and a view of a gloomy area on the edge of town. “Then the matte painter said, ‘Let’s lose the background of the town and the island, and focus on the silhouette of ships, like in a graveyard,’” he recalls. “The shot went from defining territory to being a vehicle to tell the story.” All of the VFX for Black Sails went through Crazy Horse’s LA office, which was also working on the features White House Down and Vice.  The New York office was busy with HBO’s Boardwalk Empire and the feature The Wolf of Wall Street. “There’s no difference in our workflow for a movie or a TV series,” says Paul Graff. “There’s only one way to work: as good as we can.  This is never factory work. Every shot offers new possibilities and a new learning experience.” Source:http://www.postmagazine.com/Publications/Post-Magazine/2014/April-1-2014/VFX-for-TV-Series.aspx

Tutorial: Physically Based Rendering, And You Can Too!

By Joe “EarthQuake” Wilson

This tutorial will cover the basics of art content creation, some of the reasoning behind various PBR standards (without getting too technical), and squash some common misconceptions. Jeff Russell wrote an excellent tutorial on the Theory of Physically Based Rendering, which I highly recommend reading first.

Additional help from Jeff Russell, Teddy Bergsman and Ryan Hawkins. Special thanks to Wojciech Klimas and Joeri Vromman for the extra insight and awesome art.

A New Standard

Fast becoming a standard in the games industry due to increased computing power and the universal need for art content standardization, physically based rendering aims to redefine how we create and render art.

Physically based rendering (PBR) refers to the concept of using realistic shading/lighting models along with measured surface values to accurately represent real-world materials.

PBR is more of a concept than a strict set of rules, and as such, the exact implementations of PBR systems tend to vary. However, as every PBR system is based on the same principal idea (render stuff as accurately as possible) many concepts will transfer easily from project to project or engine to engine. Toolbag 2 supports most of the common inputs that you would expect to find in a PBR system.

Beyond rendering quality, consistency is the biggest reason to use measured values. Having consistent base materials takes the guess work out of material creation for individual artists. It also makes it easier from an art direction perspective to ensure that content created by a team of artists will look great in every lighting condition.

PBR FAQs

Before we get started, it’s important to cover common questions that usually pop up when people talk about PBR.

1) I don’t know how to use a PBR system, will I need to re-learn how to create art content?

In most cases, no. If you have experience with previous generation shaders which use dynamic per-pixel lighting you already possess much of the knowledge necessary to create content for a PBR system. Terminology tends to be one of the biggest stumbling blocks for artists, so I have written a section on various terms and translations below. Most of the concepts here are simple and easy to pick up.

If your experience lies mostly with hand painted/mobile work, learning the new techniques and workflows outlined here may be more of a challenge. However, likely not more difficult than picking up a traditional normal map based workflow.

2) Will artists need to capture photographic reference with a polarized camera system for every material they wish to create?

No, generally you will be provided with reference for common materials by your studio. Alternatively, you can find known values from various 3rd party sources, like Quixel’s Megascans service. Creating your own scan data is a very technical and time consuming process, and in most cases not necessary.

3) If I use a PBR shader does that mean my artwork is physically accurate?

Not necessarily; simply using a PBR shader does not make your artwork physically accurate. A PBR system is a combination of physically accurate lighting, shading, and properly calibrated art content.

4) Do I need to use a metalness map for it to be PBR?

No, a metalness map is just one method of determining reflectivity and is generally not more or less physically accurate than using a specular color/intensity map.

5) Do I need to use index of refraction (IOR) for it to be PBR?

No, similar to the metalness map input, IOR is simply an alternate method to define reflectivity.

6) Is specular no longer a thing?

Not quite. Specular reflection intensity, or reflectivity is still a very important parameter in PBR systems. You may not have a map to directly set reflectivity (e.g. with a metalness workflow) but it is still required in a PBR system.

7) Do gloss maps replace specular maps?

No, gloss or roughness maps define the microsurface of the material (how rough or smooth it is), and do not replace a specular intensity map. However, if you’re not used to working with gloss maps, it may be somewhat of an adjustment to put certain detail in the gloss map that you would otherwise add to the specular map.

8) Can a PBR system be used to create stylized art?

Yes, absolutely. If your goal is to create a fantastical, stylized world, having accurate material definition is still very important. Even if you’re creating a unicorn that farts rainbows, you still generally want that unicorn to obey the physics of light and matter.

A great example of this is Pixar’s work, which is very stylized, yet often on the cutting edge of material accuracy. Here is a great article about PBR in Monsters University: fxguide feature on Monsters University

 

Inputs and Terminology

Artists who are unfamiliar with the concept of PBR systems often assume that content creation is drastically different, usually because of the terminology that is used. If you’ve worked with modern shaders and art creation techniques you already have experience with many of the concepts of a physically based rendering system.

Figuring out what type of content to create, or how to plug your content into a PBR shader can be confusing, so here are some common terms and concepts to get started.

Energy Conservation

The concept of energy conservation states that an object can not reflect more light than it receives.

For practical purpose, more diffuse and rough materials will reflect dimmer and wider highlights, while smoother and more reflective materials will reflect brighter and tighter highlights.

Albedo

Albedo is the base color input, commonly known as a diffuse map.

An albedo map defines the color of diffused light. One of the biggest differences between an albedo map in a PBR system and a traditional diffuse map is the lack of directional light or ambient occlusion. Directional light will look incorrect in certain lighting conditions, and ambient occlusion should be added in the separate AO slot.

The albedo map will sometimes define more than the diffuse color as well, for instance, when using a metalness map, the albedo map defines the diffuse color for insulators (non-metals) and reflectivity for metallic surfaces.

Microsurface

Microsurface defines how rough or smooth the surface of a material is.

Here we see the how the principles of energy conservation are affected by the microsurface of the material, rougher surfaces will show wider, but dimmer specular reflections while smoother surfaces will show brighter, but sharper specular reflections.

Depending on what engine you’re authoring content for, your texture may be called a roughness map instead of a gloss map. In practice there is little difference between these two types, though a roughness map may have an inverted mapping, ie: dark values equal glossy/smooth surfaces while bright values equal rough/matte surfaces. By default, Toolbag expects white to define the smoothest surfaces while black defines roughest surfaces, if you’re loading a gloss/roughness map with an inverted scale, click the invert check box in the gloss module.

Reflectivity

Reflectivity is the percentage of light a surface reflects. All types of reflectivity (aka base reflectivity or F0) inputs, including specular, metalness, and IOR, define how reflective a surface is when viewing head on, while Fresnel defines how reflective a surface is at grazing angles.

Its important to note how narrow the range of reflectivity is for insulative materials. Combined with the concept of energy conservation it’s easy to conclude that surface variation should generally be represented in the microsurface map, not the reflectivity map. For a given material type, reflectivity tends to remain fairly constant. Reflection color tends to be neutral/white for insulators, and colored only for metals. Thus, a map specifically dedicated to reflectivity intensity/color (commonly called a specular map) may be dropped in favor of a metalness map.

When using a metalness map, insulative surfaces - pixels set to 0.0 (black) in the metalness map – are assigned a fixed reflectance value (linear: 0.04 sRGB: 0.06) and use the albedo map for the diffuse value. For metallic surfaces – pixels set to 1.0 (white) in the metalness map – the specular color and intensity is taken from the albedo map, and the diffuse value is set to 0 (black) in the shader. Gray values in the metalness map will be treated as partially metallic and will pull the reflectivity from the albedo and darken the diffuse proportionally to that value (partially metallic materials are uncommon).

Again, a metalness map is not more or less physically accurate than a standard specular map. It is, however, a concept that may be easier to understand, and a metalness map can be packed into a grayscale slot to save memory. The drawback to using a metalness map over a specular map is a loss of control over the exact values for insulative materials

Traditional specular maps offer more control over the the specular intensity and color, and allow greater flexibility when trying to reproduce certain complex materials. The main drawback to a specular map is that it generally will be saved as a 24 bit file resulting in more memory use. It also requires artists to have a very good understanding of physical material properties to get the values right, which can be a positive or negative depending on your perspective.

PROTIP: Metalness maps should use values of 0 or 1 ( some gradation can be okay for transitions). Materials like painted metal should not be set to metallic as paint is an insulator. The metalness value should represent the top layer of the material.

IOR is another way to define reflectivity, and is equivalent to the specular and metalness inputs. The biggest difference from the specular input is that IOR values are defined with a difference scale. The IOR scale determines how fast light travels through a material in relation to a vacuum. An IOR value of 1.33 (water) means that light travels 1.33 times slower through water than it does the empty vacuum of space. You can find more measured values in the Filmetrics Refractive Index Database.

For insulators, IOR values do not require color information, and can be entered into the index field directly, while the extinction field should be set to 0. For metals that have color reflections,you will need to enter a value for the red, green and blue channels. This can be done with an image map input (where each channel of the map contains the correct value). The extinction value will also need to be set for metals, which you can usually find in libraries that contain IOR values.

Using IOR as opposed to specular or metalness input is generally not advised, as it is not typically used in games, and getting the correct value in a texture with multiple material types is difficult. IOR input is supported in Toolbag 2 more for scientific purposes than practical.

Fresnel

Fresnel is the percentage of light that a surface reflects at grazing angles.

Fresnel generally should be set to 1 (and is locked to a value of 1 with the metalness reflectivity module) as all types of materials become 100% reflective at grazing angles. Variances in microsurface which result in a brighter or dimmer Fresnel effect are automatically accounted for via the gloss map content.

Note: Toolbag 2 does not currently support a texture map to control Fresnel intensity.

Fresnel, in Toolbag 2 and most PBR systems, is approximated automatically by the BRDF, in this case Blinn-Phong or GGX, and usually does not need an additional input. However, there is an extra control for Fresnel for the Blinn-Phong BRDF, which is meant for legacy use as it can result in non physically accurate results.

Ambient Occlusion

Ambient occlusion(AO) represents large scale occluded light and is generally baked from a 3d model.

Adding AO as a separate map as opposed to baking it into the albedo and specular maps allows the shader to use it in a more intelligent way. For instance, the AO function only occludes ambient diffuse light (the diffuse component of the image based lighting system in Toolbag 2), not direct diffuse light from dynamic lights or specular reflections of any kind.

AO should generally not be multiplied on to specular or gloss maps. Multiplying AO onto the specular map may have been a common technique in the past to reduce inappropriate reflections (e.g. the sky reflecting on an occluded object) but these days local screen space reflections do a much better job of representing inter-object reflections.

Cavity

A cavity map represents small scale occluded light and is generally baked from a 3d model or a normal map.

A cavity map should only contain the concave areas (pits) of the surface, and not the convex areas, as the cavity map is multiplied. The content should be mostly white with darker sections to represent the recessed areas of the surface where light would get trapped. The cavity map affects both diffuse and specular from ambient and dynamic light sources.

Alternatively, a reflection occlusion map can be loaded into the cavity slot, but be sure to set the diffuse cavity value to 0 when doing this.

Finding Material Values

One of the most difficult challenges when working with a PBR system is finding accurate and consistent values. There are a variety of sources for measured values on the internet, however, it can be a real pain to find a library with enough information to rely on.

Quixel’s Megascan’s service is really useful here, as they provide a large library of calibrated tiling textures scanned from real world data.

Material values from most libraries tend to be measured from raw materials in laboratory conditions, of which you rarely see in real life. Factors like pureness of material, age, oxidization, and wear may cause variation in the real world reflectance value for a given object.

While Quixel’s scans are measured from real world materials, there is often variation even within the same material type depending on the various conditions described above, especially when it comes to gloss/roughness. The values in the chart above should be thought of as more of a beginning point, not a rigid/absolute reference.

 

Creating Texture Content

There are many ways to create texture content for PBR systems; the exact method you choose will depend on your personal preferences and what software you have available to you. Here is a quick recap of the method I used to create the lens above:

First, basic materials were created in Toolbag for each surface type using a combination of tiling textures from Megascans, measured data from known materials, and where lacking appropriate reference, logic and observation, to determine the values. Creating the base materials in Toolbag allows me to quickly adjust values and offers a very accurate preview of the end result. Often I assign base materials directly to my high poly model to get a clear idea of how the texture will come together before doing the final bakes.

After setting up my base materials I brought the values and textures into Photoshop and started layering them in a logical manner. Brass at the bottom, nickel plating, matte primer, semi-gloss textured paint, paint for the lettering, and finally the red glossy plastic. This layering setup provides an easy way to reveal the various materials below with simple masks.

Similar layering functionality can be achieved with applications such as dDo, Mari and Substance Designer.

After I have my base layers set up and blended together to represent various stages of wear, I added some extra details. First I used dDo to generate a dust and dirt pass, and then I finished it off with fine surface variation in the gloss map.

The exact method you use to create content for a PBR system is much less important than the end result, so feel free to experiment and figure out what works best for your needs. However, you should void tweaking materials values to look more interesting in a specific lighting environment. Using sound base values for your materials can greatly simplify the process, increase consistency and asset reuse on larger projects, and will ensure that your assets always look great no matter how you light them.

 Artist Q&As

We’ve been very impressed with the work shown since Toolbag 2 has been released, and would like to take the opportunity to highlight some exceptional pieces and ask the creators a few questions related to PBR.

Wojciech Klimas

Wojciech Klimas is an artist from Poland who works at DNV, currently working on the Survey Simulator project. Wojceich also does freelance work. Check out his portfolio here: www.wklimas.weebly.com

Q: What was the most difficult aspect of adapting to a PBR workflow?
A: I think the most difficult thing to remember is to maintain accurate albedo, reflectance, and roughness values. You can always cheat and adjust values to look good in one specific lighting condition, but this may look bad in other lighting conditions. If you do this correctly, with physically accurate values, it will look good in all conditions, as nothing looks better than reality.
At the beginning I had Photoshop on one screen and reference charts with reflectance values of different materials on the other, however as you gain experience it becomes easier, and you don’t need to check values as often.
Q: How do you decide which values to use for your materials?
A: By researching values from the internet. Measuring myself is way out of my reach, but I would like to try this myself, as I feel like I could learn a lot.
Q: Can you share a tip for being awesome?
A: This is a hard question. The best advice I can give is to learn physics. It really helps to understand why materials behave the way they do. There is no shortcut to being awesome, you just have to practice, practice, practice.

Joeri Vromman

Joeri Vromman is an artist from Belguim who is going to school at DAE, and is also available for freelance work between his studies. See more of work here: www.joerivromman.com

Q: What was the most difficult aspect of adapting to a PBR workflow?
A: The hardest part was piecing together information from various sources, being a single artist I did not have access to the tools and resources that many studios have, which seemed very overwhelming at first. However, once you dive in, and become more familiar with the process, it comes together quite quickly. With experience, it became apparent that the step wasn’t all that big, and that making textures for a physically based shader can be a lot faster.
Q: How do you decide which values to use for your materials?
A: The way I like to work consists of the following steps:

• Gather reference for each material type/part of the object

• Start by doing a rough block in for each material type, this doesn’t have to be exact but should be close enough so that you have a good base to start tweaking from.

For each material I start with the reflectance value, these can be found in various charts online, if I can’t find a reflectance value for a certain material, I try to determine it with logical reasoning (ie, worn out rubber will be less reflective, brass is a mix of copper and zinc, etc).

Reflectance values are the easiest to start off with, and give you a good base for the other maps. For insulators, its important to keep to keep the values within the small range that non-metals typically reflect. For metals, its important to make the diffuse black first, and then find the appropriate reflectance value. After this I will assign a quick roughness value, usually by just sorting materials into 3 categories (shiny, middle or rough). Then I pick an albedo color, paying attention here to keep things consistent and not too dark. I also toggle through various skies to make sure the materials are consistent in a variety of lighting conditions. Once this initial stage is over I fall back on observation for the fine tuning these values, since every material is different, keeping in mind the concepts of PBR. At this point I like to add a basic overlay to the normal map for materials that have a strong surface variation, such as bumpy plastic.

Its important to remember that values in the reflectance map only change when there is an actual change in material.

Q: Can you share a tip for being awesome?

A: In my opinion, although certain things have gotten a bit easier (like reflectance values to pick from), it doesn’t mean you can rely solely on those. The key to getting believable materials is still observation, and being able to convincingly translate what you see into the final texture.

Source:http://www.marmoset.co/toolbag/learn/pbr-practice

Basic Theory of Physically-Based Rendering

By Jeff Russell

Physically-based rendering (PBR) is an exciting, if loosely defined, trend in real time rendering lately. The term is bandied about a lot, often generating confusion as to what exactly it means. The short answer is: “many things”, and “it depends”, which is rather unsatisfying, so I have taken it upon myself to try to explain at some length what PBR represents and how it differs from older rendering methods. This document is intended for non-engineers (artists most likely), and will not present any mathematics or code.

Much of what makes a physically-based shading system different from its predecessors is a more detailed reasoning about the behavior of light and surfaces. Shading capabilities have advanced enough that some of the old approximations can now be safely discarded, and with them some of the old means of producing art. This means both the engineer and the artist should understand the motivations for these changes.

We’ll have to start with some of the basics so that they are well defined before we begin to highlight what is new, but if you’ll bear with me through the parts you may already know I think you’ll find it well worth the read. You may then want to also check out our own Joe Wilson’s article on creating PBR artwork.

Diffusion & Reflection

Diffusion and reflection – also known as “diffuse” and “specular” light respectively – are two terms describing the most basic separation of surface/light interactions. Most people will be familiar with these ideas on a practical level, but may not know how they are physically distinct.

When light hits a surface boundary some of it will reflect – that is, bounce off – from the surface and leave heading in a direction on the opposing side of the surface normal. This behavior is very similar to a ball thrown against the ground or a wall – it will bounce off at the opposite angle. On a smooth surface this will result in a mirror-like appearance. The word “specular”, often used to describe the effect, is derived from the latin for “mirror” (it seems “specularity” sounds less awkward than “mirrorness”).

Not all light reflects from a surface, however. Usually some will penetrate into the interior of the illuminated object. There it will either be absorbed by the material (usually converting to heat) or scattered internally. Some of this scattered light may make its way back out of the surface, then becoming visible once more to eyeballs and cameras. This is known by many names: “Diffuse Light”, “Diffusion”, “Subsurface Scattering” – all describe the same effect.

The absorption and scattering of diffuse light are often quite different for different wavelengths of light, which is what gives objects their color (e.g. if an object absorbs most light but scatters blue, it will appear blue). The scattering is often so uniformly chaotic that it can be said to appear the same from all directions – quite different from the case of a mirror! A shader using this approximation really just needs one input: “albedo”, a color which describes the fractions of various colors of light that will scatter back out of a surface. “Diffuse color” is a phrase sometimes used synonymously.

Translucency & Transparency

In some cases diffusion is more complicated – in materials that have wider scattering distances for example, like skin or wax. In these cases a simple color will usually not do, and the shading system must take into account the shape and thickness of the object being lit. If they are thin enough, such objects often see light scattering out the back side and can then be called translucent. If the diffusion is even lower yet (in for example, glass) then almost no scattering is evident at all and entire images can pass through an object from one side to another intact. These behaviors are different enough from the typical “close to the surface” diffusion that unique shaders are usually needed to simulate them.

Energy Conservation

With these descriptions we now have enough information to draw an important conclusion, which is that reflection and diffusion are mutually exclusive. This is because, in order for light to be diffused, light must first penetrate the surface (that is, fail to reflect). This is known in shading parlance as an example of “energy conservation”, which just means that the light leaving a surface is never any brighter than that which fell upon it originally.

This is easy to enforce in a shading system: one simply subtracts reflected light before allowing the diffuse shading to occur. This means highly reflective objects will show little to no diffuse light, simply because little to no light penetrates the surface, having been mostly reflected. The converse is also true: if an object has bright diffusion, it cannot be especially reflective.

Energy conservation of this sort is an important aspect of physically-based shading. It allows the artist to work with reflectivity and albedo values for a material without accidentally violating the laws of physics (which tends to look bad). While enforcing these constraints in code isn’t strictly necessary to producing good looking art, it does serve a useful role as a kind of “nanny physicist” that will prevent artwork from bending the rules too far or becoming inconsistent under different lighting conditions.

Metals

Electrically conductive materials, most notably metals, are deserving of special mention at this point for a few reasons.

Firstly, they tend to be much more reflective than insulators (non-conductors). Conductors will usually exhibit reflectivities as high as 60-90%, whereas insulators are generally much lower, in the 0-20% range. These high reflectivities prevent most light from reaching the interior and scattering, giving metals a very “shiny” look.

Secondly, reflectivity on conductors will sometimes vary across the visible spectrum, which means that their reflections appear tinted. This coloring of reflection is rare even among conductors, but it does occur in some everyday materials (e.g. gold, copper, and brass). Insulators as a general rule do not exhibit this effect, and their reflections are uncolored.

Finally, electrical conductors will usually absorb rather than scatter any light that penetrates the surface. This means that in theory conductors will not show any evidence of diffuse light. In practice however there are often oxides or other residues on the surface of a metal that will scatter some small amounts of light.

It is this duality between metals and just about everything else that leads some rendering systems to adopt “metalness” as a direct input. In such systems artists specify the degree to which a material behaves as a metal, rather than specifying only the albedo & reflectivity explicitly. This is sometimes preferred as a simpler means of creating materials, but is not necessarily a characteristic of physically-based rendering.

Fresnel

Augustin-Jean Fresnel seems to be one of those old dead white guys we are unlikely to forget, mainly because his name is plastered on a range of phenomena that he was the first to accurately describe. It would be hard to have a discussion on the reflection of light without his name coming up.

In computer graphics the word Fresnel refers to differing reflectivity that occurs at different angles. Specifically, light that lands on a surface at a grazing angle will be much more likely to reflect than that which hits a surface dead-on. This means that objects rendered with a proper Fresnel effect will appear to have brighter reflections near the edges. Most of us have been familiar with this for a while now, and its presence in computer graphics is not new. However, PBR shaders have made popular a few important corrections in the evaluation of Fresnel’s equations.

The first is that for all materials, reflectivity becomes total for grazing angles – the “edges” viewed on any smooth object should act as perfect (uncolored) mirrors, no matter the material. Yes, really – any substance can act as a perfect mirror if it is smooth and viewed at the right angle! This can be counterintuitive, but the physics are clear.

The second observation about Fresnel properties is that the curve or gradient between the angles does not vary much from material to material. Metals are the most divergent, but they too can be accounted for analytically.

What this means for us is that, assuming realism is desired, artist control over Fresnel behavior should generally be reduced, rather than expanded. Or at the very least, we now know where to set our default values!

This is good news of a sort, because it can simplify content generation. The shading system can now handle the Fresnel effect almost entirely on its own; it has only to consult some of the other pre-existing material properties, such as gloss and reflectivity.

A PBR workflow has the artist specify, by one means or another, a “base reflectivity”. This provides the minimum amount and color of light reflected. The Fresnel effect, once rendered, will add reflectivity on top of the artist specified value, reaching up to 100% (white) at glancing angles. Essentially the content describes the base, and Fresnel’s equations take over from there, making the surface more reflective at various angles as needed.

There is one big caveat for the Fresnel effect – it quickly becomes less evident as surfaces become less smooth. More information on this interaction will be given a bit later on.

Microsurface

The above descriptions of reflection and diffusion both depend on the orientation of the surface. On a large scale, this is supplied by the shape of the mesh being rendered, which may also make use of a normal map to describe smaller details. With this information any rendering system can go to town, rendering diffusion and reflection quite well.

However, there is one big piece still missing. Most real-world surfaces have very small imperfections: tiny grooves, cracks, and lumps too little for the eye to see, and much too small to represent in a normal map of any sane resolution. Despite being invisible to the naked eye, these microscopic features nonetheless affect the diffusion and reflection of light.

Microsurface detail has the most noticeable effect on reflection (subsurface diffusion is not greatly affected and won’t be discussed further here). In the diagram above, you can see parallel lines of incoming light begin to diverge when reflected from a rougher surface, as each ray hits a part of the surface with a different orientation. The analog in the ball/wall analogy would be a cliffside or something similarly uneven: the ball is still going to bounce off but at an unpredictable angle. In short, the rougher the surface gets, the more the reflected light will diverge or appear “blurry”.

Unfortunately, evaluating each microsurface feature for shading would be prohibitive in terms of art production, memory use, and computation. So what are we to do? It turns out if we give up on describing microsurface detail directly and instead specify a general measure of roughness, we can write fairly accurate shaders that produce similar results. This measure is often referred to as “Gloss”, “Smoothness”, or “Roughness”. It can be specified as a texture or as a constant for a given material.

This microsurface detail is a very important characteristic for any material, as the real world is full of a wide variety of microsurface features. Gloss mapping is not a new concept, but it does play a pivotal role in physically-based shading since microsurface detail has such a big effect on light reflection. As we will soon see, there are several considerations relating to microsurface properties that a PBR shading system improves upon.

Energy Conservation (Again)

As our hypothetical shading system is now taking microsurface detail into account, and spreading reflected light appropriately, it must take care to reflect the correct amount of light. Regrettably, many older rendering systems got this wrong, reflecting too much or too little light, depending on the microsurface roughness.

When the equations are properly balanced, a renderer should display rough surfaces as having larger reflection highlights which appear dimmer than the smaller, sharper highlights of a smooth surface. It is this apparent difference in brightness that is key: both materials are reflecting the same amount of light, but the rougher surface is spreading it out in different directions, whereas the smoother surface is reflecting a more concentrated “beam”:

Here we have a second form of energy conservation that must be maintained, in addition to the diffusion/reflection balance described earlier. Getting this right is one of the more important points required for any renderer aspiring to be “physically-based”.

All Hail Microsurface

And it is with the above knowledge that we come to a realization, a big one actually: microsurface gloss directly affects the apparent brightness of reflections. This means an artist can paint variations directly into the gloss map – scratches, dents, abraded or polished areas, whatever – and a PBR system will display not just the change in reflection shape, but relative intensity as well. No “spec mask”/reflectivity changes required!

This is significant because two real world quantities that are physically related – microsurface detail and reflectivity – are now properly tied together in the art content and rendering process for the first time. This is much like the diffusion/reflection balancing act described earlier: we could be authoring both values independently, but since they are related, the task is only made more difficult by attempting to treat them separately.

Further, an investigation of real world materials will show that reflectivity values do not vary widely (see the earlier section on conductivity). A good example would be water and mud: both have very similar reflectivity, but since mud is quite rough and the surface of a puddle is very smooth, they appear very different in terms of their reflections. An artist creating such a scene in a PBR system would author the difference primarily through gloss or roughness maps rather than adjusting reflectivity, as shown below:

Microsurface properties have other subtle effects on reflection as well. For example, the “edges-are-brighter” Fresnel effect diminishes somewhat with rougher surfaces (the chaotic nature of a rough surface ‘scatters’ the Fresnel effect, preventing the viewer from being able to clearly resolve it). Further, large or concave microsurface features can “trap” light – causing it to reflect against the surface multiple times, increasing absorption and reducing brightness. Different rendering systems handle these details in different ways and to different extents, but the broad trend of rougher surfaces appearing dimmer is the same.

Conclusion

There is of course much more to say on the topic of physically-based rendering; this document has served only as a basic introduction. If you haven’t already, read Joe Wilson’s tutorial on creating PBR artwork. For those wanting more technical information, I could recommend several readings:

• John Hable’s excellent blog post: Everything Is Shiny
• John Hable’s even better blog post: Everything Has Fresnel
• Sébastien Lagarde’s summary of Rendering Remember Me
• Come to think of it, all of Sébastien Lagarde’s Blog is good stuff
• The SIGGRAPH 2010 course on PBR
• Always worth mentioning: The Importance of Being Linear

Source:http://www.marmoset.co/toolbag/learn/pbr-theory

What is 3D Printing? An Overview.

You’ve heard of 3D printing from newscasters and journalists, astonished at what they’ve witnessed. A machine reminiscent of the Star Trek Replicator, something magical that can create objects out of thin air. It can “print” in plastic, metal, nylon, and over a hundred other materials. It can be used for making nonsensical little models like the over-printed Yoda, yet it can also print manufacturing prototypes, end user products, quasi-legal guns, aircraft engine parts and even human organs using a person’s own cells.

Fantastical? Yes. True? Yes. Here now? Yes.

We live in an age that is witness to what many are calling the Third Industrial Revolution. 3D printing, more professionally called additive manufacturing, moves us away from the Henry Ford era mass production line, and will bring us to a new reality of customizable, one-off production.

Need a part for your washing machine? As it is now, you’d order from your repairman who gets it from a distributor, who got it shipped from China, where they mass-produced thousands of them at once, probably injection-molded from a very expensive mold. In the future, the beginning of which is already here now, you will simply 3D print the part right in your home, from a CAD file you downloaded. If you don’t have the right printer, just print it at your local fab (think Kinkos).

3D printers use a variety of very different types of additive manufacturing technologies, but they all share one core thing in common: they create a three dimensional object by building it layer by successive layer, until the entire object is complete. It’s much like printing in two dimensions on a sheet of paper, but with an added third dimension: UP. The Z-axis.

Each of these printed layers is a thinly-sliced, horizontal cross-section of the eventual object. Imagine a multi-layer cake, with the baker laying down each layer one at a time until the entire cake is formed. 3D printing is somewhat similar, but just a bit more precise than 3D baking.

Stick with us and we’ll go through the various types of additive manufacturing. From FDM printing, where a material is melted and extruded in layers, one upon the other, to SLS printing, where a bed of powder material such as nylon or titanium is “sintered” (hardened) layer upon thin layer within it until a model is pulled out of it. It’s a fascinating and quickly advancing world that will change our lives as we know it.

It Begins with a Digital File

In the 2D world, a sheet of printed paper output from a printer was “designed” on the computer in a program such as Microsoft Word. The file — the Word document — contains the instructions that tell the printer what to do.

In the 3D world, a 3D printer also needs to have instructions for what to print. It needs a file as well. The file — a Computer Aided Design (CAD) file — is created with the use of a 3D modeling program, either from scratch or beginning with a 3D model created by a 3D scanner. Either way, the program creates a file that is sent to the 3D printer. Along the way, software slices the design into hundreds, or more likely thousands, of horizontal layers. These layers will be printed one atop the other until the 3D object is done.

Is it 3D Printing or Additive Manufacturing?

The term 3D printing is the common term for the correct manufacturing term of “additive manufacturing.” But 3D printing will remain the term of choice as who really is going to run around saying things like, “I’m going to go additively manufacture a new iPhone case.” No, they are going to “3D print” it. It just sounds so much cooler too, doesn’t it?

There’s no way subtractive manufacturing is going to make something like this in one clean run.

So what the heck is additive manufacturing? Someday soon enough in the future, people will look back and view our current manufacturing processes as we today view something such as blacksmithing. What’s interesting about that last sentence is that much of today’s manufacturing processes are actually very similar to blacksmithing. Both are what’s called “subtractive manufacturing.”

Subtractive manufacturing relies upon the removal of material to create something. The blacksmith hammered away at heated metal to create a product. Today, a CNC machine cuts and drills and otherwise removes material from a larger initial block of material to create a product. It’s inefficient and wasteful. Other manufacturing techniques abound but they all essentially whittle down raw material into a product.

As you’ve already surmised, additive manufacturing creates something by adding material to the object. Some here, some there, and no where it’s not needed. No waste. Very efficient. You’ll read about many types of 3D printers, but no matter the technology involved, it’s additive.

Enough talking, can I see one in action already?

Let’s take a look at one in action, before we get deeper into what is 3D printing. In the video below Bre Petris, CEO of Makerbot, demonstrates the Makerbot Replicator 2. This printer uses Fused Deposition Material (FDM) technology, which we’ll get into later.

Commercial 3D printers

While most people have yet to even hear the term 3D printing, the process has been in use for decades. Manufacturers have long used the printers in the design process to create prototypes for traditional manufacturing. But until the last few years, the equipment has been expensive and slow.

Now, fast 3D printers can be had for tens of thousands of dollars, and end up saving the companies many times that amount in the prototyping process. For example, Nike uses 3D printers to create multi-colored prototypes of shoes. They used to spend thousands of dollars on a prototype and wait weeks for it. Now, the cost is only in the hundreds of dollars, and changes can be made instantly on the computer and the prototype reprinted on the same day.

Some companies are using 3D printers for short run or custom manufacturing, where the printed objects are not prototypes, but the actual end user product. As the speeds of 3D printing go up and the prices come down, look for more and more of this. And expect more availability of personally customized products.

Personal 3D Printers

A Huxley RepRap 3D printer that has printed out its own parts.

So far we’ve only talked about commercial 3D printers. There is a whole other world of 3D printers: personal and DIY hobbyist models. And they are getting cheap, with prices typically in the range of $300 – $2,000.

The RepRap open source project really ignited this hobbyist market in the same way the Apple I microcomputer ignited the hobbyist desktop computer market in the late 1970s. For about a thousand dollars, people have been able to buy the RepRap kit and put together their own personal 3D printer, complete with any customizations they were capable of making. And what’s more, these printers print most of the parts for more printers. RepRap is short for replicating rapid prototyper, so complete self-replication, including electronic circuit boards, is the goal.

The interest in RepRap spawned scores of other low-cost 3D printers, both DIY and fully-assembled, and as the prices keep coming down, it puts 3D printers into more and more and more hands.

But do you have to be an engineer or a 3D modeling expert to create 3D models on your own 3D printer? No, not at all. While complex and expensive CAD software like AutoCAD and Solidworks have a steep learning curve, there are a number of other programs, many free, that are very easy to learn. The free version of Google SketchUp, for example, is very popular for its ease of use; and the free Blender program is popular for its advanced features.

If you don’t have your very own 3D printer, not to worry, there are 3D printing service bureaus like Shapeways and Ponoko that can very inexpensively print and deliver an object from a digital file that you simply upload to their user-friendly website. It’s almost as easy as ordering a custom t-shirt from Cafepress or Zazzle.

Even if you don’t design your own 3D model, you can still print some very cool pieces. There are model repositories such as Thingiverse, 3D Parts Database, and 3D Warehouse that have model files you can download for free.

What do all these people print? It’s limitless. Some print things like jewelry, some print replacement parts for appliances such as their dishwasher, some invent all sorts of original things, some create art, and some make toys for their kids. With the many types of metal, plastic, glass, and other materials available (even gold and silver), just about anything can be printed.

Source:http://www.3dprinter.net/reference/what-is-3d-printing