![od[force] - The worlds greatest Houdini resource](/images/system/odforce_logo.png){kind=logo}
AntiAliasingGeometry
From Odwiki
Aliasing is caused by sampling an image at discrete positions rather than having a continuous representation of the image.
Shows the exact representation of a line which needs to be sampled at discrete coordinates (i.e. the pixels).
Shows, a zero/one representation of the line segment. Each pixel is either turned on or turned off. This sampling method results in aliasing artifacts (the stair-case artifact).
If, instead, the a gray scale were used to represent the amount of the pixel which was covered by the line, the following image would be the result.
The reduction of artifacts like these is termed AntiAliasing.
Anti-aliasing also shows up in different areas of computer graphics. When looking up texture information, aliasing may occur since the texture image is being sampled at discrete coordinates.
Aliasing may also occur in channel evaluation. For example, try the expression
sin($T*180$FPS)
The frequency of the sin() wave has extremely high. This causes sampling at frame boundaries to cause aliasing. Changing the 180 to something like 100 will also show aliasing. This principle is also the cause of aliasing in many shaders.
