3D Dictionary


Alpha blending

Combining two images with different transparency levels so that one image appears visible through the other. An object's transparency is defined as its Alpha value or Alpha level.

Anti-aliasing

The removal of artifacts from an image.

Bi-linear sampling/filtering

A combination of four colors in a single 3D image used to improve that image's resolution.

Clipping

Removal of any image displayed outside of a predefined shape.

Depth cueing

Changing the color and brightness of a 3D image as it moves relative to the viewer. Color becomes less bright as the image moves away, brighter as it moves closer.

Dithering

Substituting combinations of colors you do have for colors that you don't. For example, if your computer is only capable of displaying 256 colors and you load an image that use 65,000 colors, your computer will create substitutes for the colors you don't have by combining the colors that you do. The color quality of a dithered image is inferior to a non-dithered image.

Double buffering

A way for your computer to work on an image two different ways at once. Before displaying an image, your video card calculates what a finished image will look like and displays that image while it is calculating the next image in a video stream. Double buffering affords smoother playback for video or any other multiple-frame file format.

Frames Per Second (FPS)

A measurement of how often information in a video or animation file is updated on your screen or how many frames of motion you see in a given second. Movies and television are shown at 24 fps.

Photo mapping

Overlaying a photo image on a 3D object so that the photo takes the shape of the object.

Rasterization

Transformation of a 2D object into a 3D object.

Ray tracing

A way of rendering an image. The computer computes the path of a light ray from the light source to the objects (from which the ray reflects), and further to the observer. It does this for every pixel on the monitor. This is a very intensive calculation, but the results are worth it.

Refraction

Bending of light when it passes through another substance.

Rendering

Converting a graphics image into an array of pixel colors for the display.

Shading (gouraud/phong)

Both shading methods make the surface and color of an object appear smoother. Phong shading takes more CPU time but gives better results. Gouraud shading is faster.

Texture mapping

Overlaying a graphics image on a 3D object, so that the photo takes the shape of that object.

Transparent/Translucent

An image that can partially be seen through.

Tri-linear mip-mapping

The texture map is stored at several levels of detail in a structure called a mip map. You compute the texture coordinates and the exact level of detail. This gives you the two closest levels of detail available in the mip map. In each one you perform a bilinear interpolation, and then a linear interpolation between the two levels (that's why it's called tri-linear). High-end graphics workstations (like SGI RealityEngine) use trilinear mip mapping.

Vertex

A point which marks the intersection of two or more edges of a polygon or other graphics object.

Video mapping

The same as texture mapping. In the case of video mapping, the texture is applied to an animation or a video clip.

Z-buffer

A two-dimensional array made up of a grid of points on a sea-level plane, each containing the value of the depth (z) at that point. In this way, every pixel on the monitor has a "depth value" so that the program knows which polygons are in the foreground and which are in the background.