by
The latest talk was covering the visual effects of Call of Duty: Modern Warfare 3. The game was developed as a joint effort between two game development studios, Infinity Ward and Sledgehammer Games.
Lighting
The first segment discussed lighting, the talk was given by Dave Blizard of Sledgehammer Games. He began his talk going over the history and significance of light.
- Light is made up of a combination of colors.
- Science & Religion has long given significance to light.
- Mayan’s Yucatan Temple of Kukulkan was designed with light in mind. 2 times a year, a shadow is cast on it to bring a serpent to life along the outer walls of the temple.
He showed a slide of how a sun overhead can be a religious symbol and fascinates people because it is so unusual — showing pictures of tourists capturing the moments when the shadow is directly overhead.
He then uses this point to show how a directly overhead shadow in a game looks pretty terrible and bland.
For inspiration in lighting scenes, he would look to chiaroscuro in old paintings.
He then started to follow of path of advancements in the studies of light. To use these examples to prove that lighting is something that people have been fascinated with and want to know more about.
Starting with Isaac Newton’s book of studying light and studying mica, Opticks.
Then came the lightbulb, which allowed people to freely control this mysterious force. He talked about Thomas Wilfred‘s use of art as a medium.
Then he discussed examples of movies that inspired him to create worlds never seen before, like Star Wars and Tron. And shortly after 3d technology was being used in film and television. He focused on the huge jump in 3d technology just within 10-20 years, going from crude primitive models to full composited dinosaurs in Jurassic Park in a relatively short time span.
He then showed an art piece he created for Burning Man 2007, that made use of the sun.
Then moving to Call of Duty, he started with discussing how the constant challenge is to keep the game running smoothly at 60fps with the complexities of a scene.
The lighters try to match the lighting portrayed in concept art, as close as they can. He stopped to point out the many elements in the concept art that made the scene believable and told a story, i.e. in this abandoned city there were signs of looting, damaged cars, offices papers flying around, etc.
He showed the contrast of full bright mode (flat, no shading and full brightness) in comparison to lighting mode (with the proper lighting applied). He then showed how shadows affected the scene. This showed what the lighters do to bring the scenes to life.
- Fog: He spent some time focusing on fog and the role it plays in directing a players field of view. Without fog a scene may be cluttered with too many objects, the fog can separate the further elements from the closer ones they should be focusing on.
- Reflection probes, showed an example of a debug reflection probe for a scene. I’m assuming these lightmaps are setup to be used within certain areas of the map for reflection maps.
- Rim Lighting can be used to steer player through a scene by hilighting important elements and showing a path through shadows.
- Color correction, showed the difference the color correction render pass makes.
- Depth of field, used to direct the players’ eye to the distance.
- Screen effects, like blood to show player damage.
He ended with an example of MIT’s light response studies and how they’ve been doing slow motion photography of how light bounces through and around objects. An example of the fact that even today, there’s still much more to be discovered about light. Check out more information on MIT’s visualizing light study here.
Weapons & Vehicles
What is a weapon in a FPS?
Prime factor in shooting games. It is always shown in 20% of the screen. He joked about how every screenshot and video features his weapons. “In every screenshot you can see the gun”
Weapons of Modern Warfare 3
55 weapons. 12 attachments. 3 staff, 1 contractor artists. 18 months. 30+ vehicles. Up to 3 weeks to complete some guns, 4-6 weeks for vehicles.
Evolution of Call of Duty Weapons
Earlier games had weapons with 512×512 texture maps and 1,000 tris.
Current games have weapons with up to 2000×1000 textures and up to 7,000 tris.
He explained that many weapons have licensing issues so they couldn’t say what the game was supposed to be, and by which manufacturer. Also that in earlier games it was difficult to get licensing, but since the success of the games weapons companies now come to them to see if they can get their guns in the games.
How?
He then went over the process that a weapon gets into the game. They created weapons charts to track the process of weapon development.
- Confirm weapons list with game designers
- References (photo images, getting actual weapons, replicas, shooting ranges, etc.)
- Start model
- UV mapping
- Texturing (Normal maps are mostly faked/estimated, not from up-res/de-resing models. Too slow of a process)
- Check in game
He reiterated that throughout this process, they would have to keep confirming with designers that the weapons would still be included in the game to assure no effort was wasted.
View model vs World Model
- View ~ 7,000 tri (model seen in view when holding weapon)
- World ~ 1,000 tri (model seen on the the ground or on other characters)
- View and world models share the same textures
Attachments: How?
30 attachments, 1 was cut because it broke multiplayer.
He showed how in-game gun models have all attachments attached but the unactivated ones are hidden.
Camoflage
From what I could tell, there was an alpha map used to apply camo to certain areas of the weapons texture.
- 128×128 tiling textures
- Overlay color map
He then showed some more tips to creating the weapons.
- Viewable areas of the model are most important, where most detail is. Explained they in early Call of Duty games, the unseen polygons were just deleted, but now they used simple primitives because of problems with the game engine deleted polygons caused.
- Make a useful texture library. Showed a 200 layer PSD file which acted as a palette for common elements used in weapons. There was also a separate PSD just for normal map elements.
Vehicles of Modern Warfare 3
How?
- Confirm vehicle list with game designer.
- References (They would go to Army or Navy bases, tank museums, model kits, etc)
- Start model
- UV
- Texture
- Check in game
Hovercraft example.
- To save time, he created a texture first and matched the UVs up to the texture after he modeled it.
- Color map takes 2 weeks.
- Explained a bit how cosine power map worked, how blacks areas will catch light and whatnot
Destructibles/Destroyed States
Showed a test map used to test rigging and animation of destroyed vehicles
Vehicle know hows
- Maximize detail at eye-level
- Minimize detail where you don’t see
- Geometry tells much more than normal map
Visual Effects
The first part of this talk was given by David “DJ” Johnson of Infinity Ward. The first subject was the visual effects of the London train crash segment of Modern Warfare 3.
An example of the Radiant editor from Call of Duty 4
London Train Crash
- Artists explain what’s going to happen in the scene (trains crash, tumble through pillars, sparks, etc.)
- Models are created in Maya -> exported to Radiant -> to animators. Scene is first roughed out in Maya as playblasts.
- Many iterations of how the train bounces around.
- First animated in engine & scripted, without Visual Effects applied first.
- Once animation is finalized, Then VFX takes over and adds effects. Tearing of train. Pillars destroyed. Ideas of sketched out and discussed with modelers, would would then create these new assets.
- Columns / Pillars breaking using effects similar to those used in earlier games (breaking through doors), so there could be some reuse of techniques.
- Conservation of Mass. Same amount of material removed from pillars is shown in effects (i.e. same volume of mass missing from pillars is shown in particle chunks).
- Goes to modeling department, they make destroyed columns and train.
- Layers of the effects. (Small pebbles, large pebbles, sparks, smoke, dirt, dust, debris)
- Size of particles had to be exaggerated in size, much larger than realistic. Even though unrealistic, it looked better in game.
Some Math
The Golden Rule is that the game must always maintain a 60fps framerate no matter what. He then broke down how much time that really is, and how much of a budget they had for visual effects.
- Careful to balance particles to keep fps.
- 2048 particles is the limit of the game engine
First pass at drawing characters, environment, HUD, etc takes 5-8 ms of 16.6 ms budget.
He then showed some profiler programs that show how much effects are used in a given moment of gameplay, and how long it takes to process them. He showed Pix, which is an Xbox specific profiler. It shows how long each layer of effects takes to draw.
Environments & static elements are drawn first, animated characters and closer objects, then effects, and finally colorization is applied.
He then went over the different types of FX.
- Ambient FX
- Moment FX (cinematic moments)
- Gameplay FX (guns, grenades, flashes)
- Destructibles
Then he ran through a video of a stage in debug mode and showed how they would give an FX pass to different elements in the stage, highlighting problems that might show up and how to avoid them.
- Particle placement on multiplayer maps is more selective because of the unpredictable nature of multiplayer play (you could have 16 players stand in a single room and all throw smoke grenades). Single player conditions are more known and controllable.
- Editor allows tweaking of particles realtime in levels and demo levels.
- Every item that should react should be run through destructible effects, otherwise they don’t react and have infinite mass.
Storytelling w/ Visual Effects
Next up was Sandy Lin of Sledgehammer Games. She focused on storytelling through visual effects.
The first part of her talk focused on the Berlin stage in the game. She started with going over the concept.
Concept of Berlin
Concept artwork for the Berlin stage
The player would be entering a war-torn city. The scenes in the stage would tell the story of how the player visually discovers what is going on. And leads to a “big moment”, like a building falling in front of the player.
Steps to Creation
- Research (studied films like 2012, demolition videos, etc.)
- Design
- Execution
- Primary Effects: Fire, smoke, debris…
- Secondary effects: Other layered effects caused by the main action (i.e. building falls and hits other buildings, powerline snap and electricity flies through the air)
Challenges
- Hitting the limits of the game engine
- Zone Watcher – in engine tool designed to break up stages into “active” and “inactive” zones. For instance, when the building falling scene becomes active it enters a new zone, which kills the effects in other zones.
- Overdraw
- Selling scale and depth
Creating the Berlin tower collapsing segment took 8 months and is one of the biggest “moments” in the game.
For another stage, where buildings were blown up and debris had to slide down a mountain, they used rigidbody simulation in Maya using Nvidia Physx.
- Animation was first created as a simulation in Maya.
- After animation is finalized, the animator can start tweaking objects to control the look.
- Gave control back to the player to give the feeling that it’s not just a movie.
- Learned to use Maya Rigidbody to sell “moments” in the game.
Q & A
There were a few questions asked for Q & A, I’ll just focus on one.
How was the story developed?
- Development starts early in the process of game’s development
- Game designers come up with interesting ideas for fun gameplay
- The game will follow what previously happened in the game series
- Collaboration between both Infinity Ward and Sledgehammer Games
- As the level is developed, more story elements are layered on to make gameplay more dramatic
————————–
All in all, it was a great and detailed talk and I thank the speakers for taking the time to show how they made it happen!
The talk got my mind flowing. The complexity of some of the epic scenes in this game seem less daunting once understanding some of the process involved in the development. Interesting tidbits to me were the limitation of 2048 particles and being able to pull off a great variety of effects. I’ve been recently struggling to get more than a few hundred particles in Flash 11 using Away 3D 4, thinking that I need to 10,000 to make something awesome. Now I’m thinking of ways to use that limitation to pull off something nice.
While researching some Call of Duty Mod stuff for this post, I found very detailed instructions for scripting mods and using the game editors. It surprised me to see such a wealth of information of the game. I intend to look a bit into how the games system work and see if there’s anything to learn from their techniques. It was also a surprise (sorta) to find out that the Call of Duty engine and editor are descendants of id’s Quake 3 engine and tools.
If you’re in the LA Area, and interested in events like these, check out the Gnomon website and sign up for their newsletter! Good stuff!
