Talk:3D computer graphics/Temp
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A rewrite of 3D computer graphics is taking place here. Please feel free to contribute; keep in mind some of the existing problems that have been brought up on the talk page.
Article revision follows:
3D computer graphics is a field of study within computer graphics in which numerical models of objects are stored and manipulated in three dimensions by a computer. It is most commonly used to generate visual images, often used in film and television productions, computer and video games, commercial illustration, engineering, and scientific visualization. The term may also refer to images produced using such a model.
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The basics of 2D and 3D computer graphics – the coordinate projection plane
"3D Computer graphics" is the science and method of projecting 2D (flat) and/or 3D mathematical models (which include depth) onto a flat projection screen, typically a computer monitor. Since one obviously cannot see depth because the computer screen is flat or 2D, the rendering portion of the computer graphics "machine" fools the observer into thinking that he is actually viewing a 3D object on the 2D plane. This 2D to 3D projection is accomplished via the application of finite mathematical models and algorithms (calculation pipeline) within the ‘graphics rendering engine’ and the final presentation of the 'spoofed' 3D image onto the computer screen.
To conceptualize the 2D to 3D rendering process, think of a computer screen as a Cartesian coordinate plane with thin imaginary horizontal lines representing the X axis and thin imaginary vertical lines as the Y axes. The granularity or resolution of the typical computer screen is 1024 lines by 768 lines. Each imaginary horizontal line is a referred to as a ‘raster’ and the intersection of the lines creates points referred to as pixels. To fully understand the part of the human brain that ‘sees’ depth, we first must understand the underlying concepts like: ‘vanishing points’, ‘shadows’, ‘color gradients’, ‘light sources and placement’, trigonometry, matrix mathematics, etc. In 3D graphics, that is 2D graphics presented as having depth, a third plane, the ‘Z’ coordinate is introduced. Imagine yourself looking into the front of computer display screen, all the way through it out the back as if it were clear - this is the negative Z coordinate. Inversely, further imagine that you are directly behind the glass on the computer screen, looking at the back of your chair, this is the positive Z coordinate. To understand the 3D concept even more, think of a cardboard cube with the dimensions of twelve inches deep and twelve inches high. The ‘graphics origin’ ( X, Y, Z = 0 ) would fall at six inches toward the center of the cube, and six inches from the top of the cube, or at a point dead-center. Now, pretend like the cube is now one mile high and one mile deep – this is the area that can be utilized in rendering the 3D computer ‘graphics model’.
How 3D graphics are presented on a 2D plane
You now already know now the arena of 3D computer graphics as a 3D Cartesian coordinate ‘volume’. Now you will understand the basic concepts of our visual perception of depth. Imagine yourself standing at one end of a picket fence and you are looking down the length of it, which happens to be one mile long, you obviously would notice that the height of the fence appears to diminish along with it's length. If this fence were long enough, the fence would appear to us as actually meeting with the ground and would have no height at all. This is the ‘vanishing point’ and it is a very important part of the 2D to 3D projection. When you look at a 3D mathematical model that has been projected onto the computer screen it will appear to be ‘scaled down’ as you look towards the back of the model. The programmer has the ability to control many effects of the scene being rendered: the lighting (ambient, specular), reflectivity of the surface of the model being rendered as well as others. All of these computer generated 3D effects trick our brain into believing that we are actually seeing a three dimensional scene when in reality it is flat. You have two eyes and the object you look at in real life creates an imaginary triangle with the baseline between your eyes and the sides of the triangle leaving each eye and meeting at the apex of the triangle, or the object you are looking at. This gives you depth preception and is calculated in your brain via trigonmetric functions. These similar trigonmetric functions can be used to create triangles and regular polygonal shapes or models in 3D graphics.
The anatomy of a 3D model
It is important that you now know that Computer Graphics demonstrated to the viewer typically as ‘scenes’. These scenes are typically composed of ‘models’ or artifacts; they may contain objects such as moving water in a stream or clouds passing through the blue sky on a sunny day. A simple model is generally defined as a ‘shape’ or ‘object’. The shape is defined in its most primitive state as a collection of Cartesian coordinate triples X, Y and Z. Each triple represents one point in 3D space (remember the cardboard cube); two points define a line and three points define a triangular ‘plane’ if they are in a loop. Note that the three points may define two connected line segments also. In this example let us assume that we are to create a simple polyhedral shape, the absolute simplest regular polygon shape we could create is called the tetrahedron or four connected triangle planes. We could place this shape at the origin (X,Y,Z =0) and define the three sets of points for a total of twelve points to define our shape. Note that the four sides of our shape would actually share four common endpoints for the tips of the triangles so practically speaking we could define the shape as a total of four points but the rendering engine would not know how to draw the shape.
If our rendering engine were in ‘wire frame’ mode then the tetrahedron would appear as a set of lines when drawn. Contrast this to ‘solid’ mode where each triangle side is drawn as a flat plane - this is what really gives the appearance of the 3D graphics model. Add in enhancements like lighting, shadows, texture mapping (wrapping the model with a picture or texture), animation and other enhancements and you will have a model that approaches near life like in appearance.
3D models then are a series of points, usually tripled to create a triangle, and many triangles make up a shape. Although ‘quads’ can be used instead of ‘triples’ the triangle is the best primitive to use because it is the smallest polygon and will ‘bend’ into smooth surfaces depending on the number of subdivisions of the triangles. The 3D models may be predefined as an array of static point entries to speed up the rendering process or may be defined programmatically via algorithms at render time. This depends on the programmer that is creating the models.
Many 3D ‘drawing’ programs and ‘gaming engines’ allow shapes and objects to be manipulated at run time but the basic shapes are static at the time of selection for inclusion into various ‘scenes’ to speed up the rendering process.
How 3D graphics are created
3D computer graphics are typically created with the aid of specialized computer software. Two basic steps are required:
- Modeling: Three-dimensional data, usually in some coordinate system, is entered into the computer
- Rendering: The computer produces a visual representation of that data
The internal representation of the data in the computer is commonly referred to as the model; it may be a model of real-world objects or phenomena, such as a weather system, building, or automobile, or an imagined object such as a flying saucer or dinosaur.
Some older discussion of the proposed article structure
Planned Structure
- What is 3D Computer Graphics ?
- What is 3D ? show picture of 2d surface and in contrast a 3d object
- Now, what is graphics ? some digital painting and a digital rendering
- So, 3D computer graphics ? 2 thumbnails; a pic from a 3D gallery and a still from a scene in a movie
- Where is it used ?
- Scientific Visualizations 3d medical imaging, weather
- Movies/Television say, LOTR 1, Shrek and one inconspicous use; ads
- Games any of the 1000+ Doom-style from past 5 years
- Training Military and commercial simulation for training
- Architecture/Plant Design CAD Models for Presentations, Construction Guidence, and Operation Scenarios
- Concepts in creation software-independent, specific technique independent description
- Process in creation
- Modelling 2-3 screenshots
- Layout and camera first, some random arrangement and then a setup with 2 different angles and perhaps different "lenses"
- Shading and Lighting wireframe, flat, gouraud and final render side-by-side
- Animating first, two wireframes at two keyframes. Then, 6 pics including initial 2 + 4 interpolations
- Rendering wireframe and rendered side by side
- Compositing something like Gollum or pics of chroma-keying
- Tools employed major and minor softwares + basic description of hardware used
- Resources on the net
- Free demo program downloads XSI Experience, gmax ..etc
- Tutorials
- CG news sites/blogs CGChannel, Renderosity ...etc
- Participation on the net
- Popular webrings/art galleries and communities RAPH.com ..etc
- Discussion forums CGTalk.com, Digital Sculpting ..etc
Google Search: 3d quickbasic (http://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=3d+quickbasic)
Google Search: "blue moon rendering toolkit" (http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%22blue+moon+rendering+toolkit%22)
Google Search: "3d engines" (http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=%223d+engines%22)
Discussion of shadow algorithms including Shadow Volumes and Shadow Maps.
Perhaps this page should be just a short summary, with the details moved to separate pages such as Solid modelling, Computer animation, 3D computer animation, 3D graphics editors, 3D rendering, etc. Each of these topics can fill several books.. Jorge Stolfi 23:58, 7 Mar 2004 (UTC)
- And so can almost all topics at Wikipedia Gyan
- And so is done quite often. Mikkalai 16:11, 21 Mar 2004 (UTC)
- But I would leave the finer details in those topics, to their individual pages. In the outline above, the subtopics aren't meant to be comprehensively covered. Just an intro, along with illustrations. Leaving them out altogether would be a disservice. -- Gyan 17:39, 21 Mar 2004 (UTC)-
- I agree. An overview article here, with sections dealing with each sub-topic at a superficial/introductory level, each of which the points to a detailed article on that sub-topic, is the usual way of solving these problems. -- Anon.
I second Jorge's proposal and also suggest a history secion. Mikkalai 16:11, 21 Mar 2004 (UTC)
I'm gonna start on some of this tomorrow using Blender_(program). enigmasoldier 12:29, 27 Mar 2004 (UTC)
Planned Structure
I suggest merging the categories "Games" and "Training" (under "Where is it used?") into a category named "Interactive Media". James C. 03:00, 2004 Jul 24 (UTC)
Some specific addressing of common software -- if only a link to a List of 3D Modeling and Rendering Software sort of thing, should exist. Reason being, it's absurd to go to an article on modelling and not have some way to get to the articles on software that employ it.
-- Dodger
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There should be some discussion of the history of 3d computer graphics, and the impact of 3d graphics upon computer games, especially the boom of 3d with the invention of the third gen consoles, Playstation, dreamcast, N64, and the invention of PC 3d graphics cards. I believe this would be of more interest to the average user than the highly technical nature of the article at present.
Molloi