WRIT 340
Dr. Ramsey
Illumin Paper
10/19/2011
Alexander Silkin
Biography
Alex is a junior majoring in Computer Science Video Games. He was born in Moscow, but lived
in China since he was 10. After he graduates, Alex hopes to stay in the US and work for a
software development firm.
Contact and Email
Phone: (213) 400-2585
Email: alex.silkin@gmail.com
Key Words
Video Games, 3D Graphics, 3D rendering, polygon mesh, shader
Multimedia Suggestions
A basic, 10 minute tutorial that demonstrates how to model a human hand:
http://www.youtube.com/watch?v=J1mExXURsWk
Euclideon’s Unlimited Detail presentation and comparison to traditional polygonal graphics:
http://www.youtube.com/watch?v=5dWHsrRqUx4&feature=fvst
A demonstration of how a skeleton-based rig can move and animate a character’s limbs:
http://www.youtube.com/watch?v=X2Uk-r0BNJE&feature=related
Abstract
Video games are becoming an increasingly mainstream form of art and entertainment.
At the same time, the medium’s visuals have evolved at a similarly exponential rate. Modern
video games provide extremely immersive experience with detailed graphics that are
progressively closing in on photorealistic quality. Despite these rapid improvements, the
foundation of real-time 3D graphics has remained relatively constant. The 3D production
pipeline still consists of 6 core stages: pre-production, 3D modeling, shading & texturing,
animation, lighting and rendering & post-production. This paper will explore the modern
methodologies that are employed during these stages to give an overview of how today’s video
games deliver their incredible visuals.
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Introduction to Real-Time 3D Computer Graphics
Have you ever wondered how today’s amazing 3D graphics in games are possible?
Modern real-time 3D computer graphics have evolved exponentially since the first primitive 3D
games at the end of the 20th century. However, the fundamentals of real-time 3D graphics have
stayed relatively constant because the evolution of 3D technology has been mostly driven by
improvements in computer hardware and integration of new algorithms within the traditional
computer graphics pipeline. The computer graphics pipeline refers to the process of creating 3D
assets and delivering them to the audience in their finished form. This process is broken down
into 6 stages: pre-production, 3D modeling, shading & texturing, animation, lighting and
rendering & post-production [1]. We need to explore these different stages to fully understand
and appreciate the technology behind the incredible visuals in 3D games.
During the pre-production stage, the vision for a 3D asset is formed and finalized. Artists
and engineers involved in the project brainstorm ideas to produce a design of the asset. The
design’s aesthetics must be homogenous with the style of the whole project. At the same time,
the design must be feasible within the project’s limited resources, such as time, personnel and
technology. The design must also be fairly detailed, as it will guide the creation of the asset
through the next 5 stages of its production. Consequently, the finished design usually contains
concept art of the 3D asset, which is used as a reference to create the model of the 3D asset.
3D models are usually constructed using a modeling package - software specifically
designed for creating 3D models for movies and games. There are many ways to represent
models in 3D space, but the oldest and one of the most popular is using polygons. Because of
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their relatively low processing requirements, 3D polygon graphics are especially prevalent in
projects that rely on real-time rendering, or on the fly graphics processing, such as video games
and simulations. A polygon is defined as a “bounded region of a plane” [2]. These bounds are
formed by lines that join together at points called vertices. Vertices are defined by their
positions in 3D space expressed with positional vectors in relation to a predetermined origin of
the 3D space. Consequently, a collection of all the vertices is the most basic way to express a 3D
model constructed out of polygons, also known as a mesh [2]. This system allows 3D modelers
to create meshes that represent any object by approximating its shape with flat polygons (see
Figure 1).
Mark Allen 2007/
http://www.playtool.com/pages/basic3d/basics.html
Figure 1: A polygonal representation of a table
A model’s appearance can be improved with greater detail by using more polygons, thus raising
the model’s polygon count. However, rendering more polygons requires more processing
resources, which is particularly problematic for real-time rendering [3]. Consequently, artists
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are usually specifically informed about the planned poly count limits for each 3D asset and the
whole 3D scene.
The improvements in 3D game graphics have been significantly driven by the increased
poly counts of objects within games. This increased detail is made possible by the
improvements of computer hardware, which allows computers and gaming consoles to process
more polygons at a rate sufficient for real-time animation, which is at least 30 frames per
second. Real-time animations must run at least with of 30 frames per second, or the animation
will seem to lag as there will be enough time between each frame for an observer to be able to
distinguish each individual frame. However, practically, real-time simulations must aim to run
with much higher frame rates, because frame rates fluctuate sporadically depending on the
present amount of detail on screen, and may consequently fall below the desired levels. At the
same time, game developers are constantly thinking of new tricks to creatively overcome poly
count limits. An example of this is swapping high-polygon versions of models by low-polygon
versions when the models are far away from the camera. Similarly, objects very far away can
simply be 2D planes with images, usually scenery, effectively serving as cardboard carvings
surrounding the scene. These tricks conserve the polygon count in the entire scene and thereby
allow higher polygon detail on objects closer to the camera. Consequently, the race for better
graphics in games consists of discovery and improvement of such techniques in addition to the
traditional rise of poly count limits using faster hardware. However, such tricks are far from
perfect. In the first example, a player can notice the model swap if he or she pays attention. At
the same time, many modern games allow players to use tools, such as binoculars, to look into
the distance of virtual worlds, which can expose both the low poly versions of models and the
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aforementioned fake scenery. Consequently, programmers are constantly trying to invent ways
to overcome problems plaguing these tricks and polygonal graphics in general. In fact, several
individuals have proposed alternatives to polygons, such as voxels, which are 3D versions of
pixels. However, while all proposed alternatives overcome some drawbacks of polygonal
graphics, in general none have been found adequate to replace polygons completely. This is
because after many years, hardware, algorithms and artistic techniques have been heavily
optimized for polygonal graphics. The debate surrounding the Unlimited Detail technology
embodies this conflict between traditional and new 3D methodologies.
Unlimited Detail is currently under development by Euclideon, a Brisbane-based
company. Ueclideon promises that their technology will revolutionize graphics in 3D games
using innovative application of voxels called point clouds. According to Euclidion, Unlimited
Detail technology “can process unlimited point cloud data in real time, giving the highest level
of geometry ever seen” [4]. Furthermore, Bruce Rober Dell, Euclideon’s CEO, has stated that
Unlimited Detail can “do all this with modest, rather than excessive, processing power” to
deliver graphics more detailed than traditional polygonal graphics “by a factor of 100,000
times” [5]. Naturally, industry experts have responded with much skepticism to Dell’s grandiose
claims. One of these experts is John Carmack, who is the creator of the original Wolfenstein,
Doom, and Quake 3D engines and consequently considered to be one of the “fathers” of 3D
games. Carmack has expressed relatively moderate cynicism towards Ueclidion’s claims, as he
has stated his belief that there is “no chance of a [Unlimited Detail] game on current gen
systems, but maybe several years from now. Production issues will be challenging” [6]. On the
other hand, Markus Alexej Persson, another influential individual in the game industry, has
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been much more critical of the new technology, going so far as to proclaim that “[Unlimited
Detail is] a scam” [7]. Person has backed up his claim by stating that essentially “[Euclideon]
made a voxel renderer”, which suffers from typical draw backs in voxel technology: limited
number of unique objects in a scene and difficulties in applying traditional animation
techniques to voxels [7]. Persson is known as “Notch” and is famous for developing Minecraft,
which uses stylistically low detail voxel technology for terrain alongside traditional polygonal
graphics for characters. Persson’s voxel related experience grants authority to his criticisms and
conclusion that “[Euclideon is] carefully avoiding to mention any of the drawbacks” because the
company is seeking funding [7]. Indeed, during an interview with Euro Gamer, Dell has shown
an inability to directly confront the criticisms of Unlimited Detail, “often choosing to be
humorously defensive in answering even basic technological questions, or simply evading them
altogether” [8]. Dell has further eroded his credibility with his contradicting statements, saying
that Euclidean has learnt from its past mistakes and will no longer show unfinished features,
and yet “[attempting] to put the new video into context, saying that the decision to go ahead
with a new demo only came a few weeks ago" [8]. This lack of credibility and lack of support
from the games industry exemplifies the issues that challenge the development of alternative
3D graphics technologies. Consequently, in the last twenty years, polygonal modeling has been
thoroughly entrenched within the traditional 3D production pipeline for games.
During the next stage in the 3D production pipeline, called shading and texturing, game
developers add texture maps to a finished 3D model to give it color and more detail. A texture
map is essentially a 2D image that is projected onto the surface of a 3D model [9]. Texture maps
influence lighting algorithms during rendering to not only display color on a model’s surface,
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but also create lighting effects and even display visual illusions that change the appearance of a
model’s geometry. However, in order to create an effective texture map that will properly
cover a model’s surface, artists need to first create a custom UV layout for the model. A UV
layout is “a visual representation of a 3D model flattened onto a two dimensional plane”,
where U and V standing for the coordinates on a 2D map that covers the 3D surface of a model.
[9] Image sections contained within a polygon of UVs are mapped to appropriate faces on the
model. The process for creating a UV layout is called UV unwrapping, when an artist lays out
flattened UV sections of the model within a 2D square. A texture map is created using the UV
layout as a reference, allowing artists to affect specific regions on the model. When a texture
map is applied to a model, it is automatically scaled to fit within the 2D UV space, thus giving
artists the freedom to choose the resolution of texture maps. However, similarly to a model’s
poly count, higher resolution textures require more memory and consequently the resolution
of texture maps is restricted by memory limitations. There are also different types of texture
maps, such as color, specular, bump, reflection and transparency maps [10]. Color, or diffuse,
maps allow artists to add different colors or textures to different regions of a model. Specular
maps, also known as gloss maps, manipulate the light algorithm to give a shiny appearance to
specific regions of a model’s surfaces. Bump, displacement, or normal maps effectively change
the appearance of a model’s geometry by affecting the light algorithm to render surfaces at
displaced positions. This allows bump maps to add 3D detail without sacrificing much
processing resources in comparison to the cost of raising a model’s polygon count (see Figure
2). Lastly, reflection and transparency maps, as their name implies, make surfaces reflective and
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transparent respectively. All these texture maps can be used in conjunction to achieve the
appearance of any material that artists desire.
Mark Allen 2007/
http://www.playtool.com/pages/basic3d/basics.ht
ml
Figure 2: The top model of the Earth only has a
diffuse map attached. The bottom model makes
use of a bump map to create the illusion of more
detail
A fully textured 3D asset is ready to be animated if necessary. Traditional computer
animation uses key frames, where the object is manipulated in a special manner at specific
frames, which causes the object to smoothly transition, or tween, between the frames as the
animation is played. A system that uses a skeleton has been developed to complement
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traditional animation techniques to allow 3D character animation. In this system, an artist first
“rigs” a model to attach it to a skeleton with appropriately positioned joints. Then, the artist
paints “skin weights” to distribute the influence of each joint on the various portions of the
mesh’s skin to achieve realistic deformation of the skin during movement. Finally, the model is
ready for animation and the character’s joints are rotated at specific key frames. When the
animation is played, the joints smoothly rotate between the predetermined angles at the key
frames. This is the fundamental methodology behind all the moving characters in games today.
However, it would be impossible to see all the action within games without a source of
light. Consequently, during the lighting phase of production, artists position lights around the
scene. The four different lights that are used in 3D graphics are: ambient, directional, point, and
spotlight. The different properties of these lights allow artists to emulate the different kinds of
environments in real life. However, for real-time simulations, like games, it would be very
resource-expensive to calculate the real-time light interactions, or what is known as dynamic
lights, for all the objects in a scene. Consequently, developers use static lights, which allow the
developers to calculate shadows in the scenery during development. These shadows can then
be applied as a light map, a type of texture map, to surfaces on objects to display the shadows
without real-time calculations (see Figure 3).
Mark Allen 2007/ http://www.playtool.com/pages/basic3d/basics.html
Figure 3: This illustration shows the effect of a light map on what is otherwise a bland brick wall
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This allows the developers to conserve computational resources to only calculate the effects of
dynamic lights on certain objects, particularly moving characters. However, it is impossible to
use this technique to achieve the quality of a scene entirely lit by dynamic lights.
After all the hard work in the previous stages, developers are finally ready to show the
fruition of their efforts during the rendering stage. However, unlike 3D movies, 3D games are
rendered real time, which means that this stage effectively occurs during rendering each frame
that a game is played in real time. In order to display the 3D contents of a scene on a 2D screen,
the game must effectively flatten all the objects to enter all the objects in what is known as
screen space [11]. However, further steps must be taken to improve the quality of this 2D
representation on the screen. This is because of the limited number of pixels on a display
screen, which cause texture artifacts and aliasing, known as “jaggies”. Texture artifacts are
minimized using texture filtering, which averages out the color value of a pixel based on the
average color values of the pixels’ region on the texture. Similarly, anti-aliasing is a process that
involves calculating an average of multiple samples of an image (see Figure 4) [3]. Both these
techniques can be performed at various levels at the expense of computational resources,
which will impact the frame rate of the simulation.
http://www.cdrinfo.com/Sections/Reviews/Specific.aspx?ArticleId=14349
Figure 4: The images show various levels of anti-aliasing from left to right: 0xAA, 2xAA, 4xAA
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The underlying technology behind the amazing 3D graphics in games today is deeplyrooted within the techniques mastered during the birth of 3D games. In the past twenty years,
3D graphics in games have been mostly pushed by exponential improvements in hardware
which allow greater polygon counts in scenes. However, no matter how high the poly count
limits rise, they still constrain artists. Consequently, game developers have to rely on various
engineering and artistic tricks, which are inherently flawed in one way or another. At the same
time, no effective alternatives to polygonal graphics have been found. However, one great
development in the area of 3D game graphics is the growing popularity of 3D displays. Because
3D games are inherently 3D, there is little effort in displaying games on 3D displays. There is still
uncertainty about the technology’s impact on visual health, and a report by the American
Optometric Association admits that visual health can be influenced by “poorly made 3D
products”, poor equipment, or existing individual’s eye problems [12]. In spite of this, the
technology is becoming increasingly popular, and soon the trend will bring consumers
affordable large glasses-free 3D screens. These developments seem like a natural evolution of
3D graphics in games. 3D screens will allow us all to finally experience the worlds depicted in 3D
games the way they are meant to be experienced – in 3D.
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Works Cited
[1] Justin Slick. (2011) About.com. [Online]. http://3d.about.com/od/3d-101-TheBasics/tp/Introducing-The-Computer-Graphics-Pipeline.htm
[2] Bob Pendleton. (2008, November) Game Programmer. [Online]. http://gameprogrammer.com/5poly.html
[3] Rene Froeleke. (2011) CDRinfo. [Online].
http://www.cdrinfo.com/Sections/Reviews/Specific.aspx?ArticleId=14349
[4] Euclideon. (2010, September) Unlimited Detail Technology. [Online].
http://unlimiteddetailtechnology.com/home.html
[5] Matthew Murray. (2011, August) Extreme Tech. [Online].
http://www.extremetech.com/gaming/91854-unlimited-detail%E2%80%99s-non-polygon-3d-getsmore-unlimited
[6] John Carmack. (2011, August) Twitter. [Online].
https://twitter.com/#!/ID_AA_Carmack/statuses/98127398683422720
[7] Markus Alexej Persson. (2011, August) The Word of Notch. [Online].
http://notch.tumblr.com/post/8386977075/its-a-scam
[8] Richard Leadbetter. (August, 2011) Euro Gamer. [Online].
http://www.eurogamer.net/articles/digitalfoundry-vs-unlimited-detail?page=2
[9] Justin Slick. (2011) About.com. [Online]. http://3d.about.com/od/3d-101-The-Basics/a/Surfacing101-Creating-A-UV-Layout.htm
[10] Justin Slick. (2011) About.com. [Online]. http://3d.about.com/od/3d-101-The-Basics/a/Surfacing101-Texture-Mapping.htm
[11] Thierry Tremblay. (1999, August) GameDev.net. [Online].
http://www.gamedev.net/page/resources/_/technical/graphics-programming-and-theory/3dbasics-r673
[12] American Optometric Association, "3D In The Classroom," American Optometric Association, St.
Louis, Public Health Report 2011.
[13] Mark Allen. (2007, July) PlayTool. [Online]. http://www.playtool.com/pages/basic3d/basics.html
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