When using an image clip, you can define if and how it will be filtered when rendered. There are two ways to filter the image:
• In the Image shader, you can specify elliptical filtering.
• In the Image Clip property editor, you can specify Multi-Resolution Mapping.
Elliptical filtering is usually used on high-detail textures that are moving near or far from the camera. This filtering process is much less memory-intensive than using antialiasing in the render options.
Elliptical filtering projects a circle onto the object’s surface. The circle is elliptical (hence the name of the filtering process) so that it can cover all of the texture’s pixels, which are then looked up and computed when a color value is returned for all the pixels in the circle.
You can find the elliptical filtering options on the Filtering tab of any Image shader property editor.
Multi-Resolution Texture Mapping
You can use pyramid mapping—or MipMapping—to smooth textures when rendering. Pyramid mapping performs a pre-blurring of a texture that is far from a camera.
The classic example (as previously shown) is a very long checkerboard texture that seemingly goes off into infinity, but starts near the camera. As the grid gets farther away, the texture flickers and breaks up as the renderer samples only a single, far-away pixel.
This can be corrected with antialiasing, but it may become very time-consuming when rendering. Pyramid mapping blurs the distant texture so the render doesn’t return a specific pixel color; instead, it returns an interpolation of several distant pixels. This solution is less time-consuming than antialiasing and yields excellent, realistic results.
To use pyramid mapping
• Select Enable Multi-Resolution Texture in the Image Clip property editor (Texturing tab).
Use the Blurring slider to control how much interpolation—or blurring—the textures will have applied to them. More complex textures should have a higher blur applied to them.
Autodesk Softimage v.7.5