Autodesk LIGHTSCAPE, Manual

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Batch Processing Utilities B
262
Lightscape
Antialiasing in LSRAY
The lsray utility uses a multisampling scheme to antialias images that contain high-frequency details. The anti-
aliasing algorithm functions as follows:
1.
One ray is cast at each corner of a pixel, resulting in a (possibly) different color at each corner.
2. The corner colors are compared to compute their contrast (relative difference) between the brightest and
darkest corners.
3.
If the contrast is below a user-specified threshold, the corner colors are averaged to yield the pixel color.
4.
Otherwise, the pixel color is computed by averaging the result of the user-specified number of rays stochas-
tically cast within a region of user-specified radius and centered about the pixel center.
This antialiasing scheme can be accessed by the user by:
• lsray option -aaa <t> <n> <r>, where: <t> is the contrast threshold in the range [0..1], <n> is the level of sam-
pling resulting in <n>*<n> rays used in step #4 above, and <r> is the radius of the sampling region used in step
#4 above.
Note:
Specifying <t> = 0 forces all pixels to be computed as specified in step #4. Steps 1-3 are ignored.
Specifying <n> = 1 forces all pixels to be computed using a single ray at the exact center of each pixel.
Specifying <t> > 1 and <n> = 0 forces all pixels to be computed using the corner average, as described in step
#3 above.
• lsray option -aa <l>, where <l> is the antialiasing factor as an integer in the range [1..10].
This second option provides access to the antialiasing scheme without requiring you to specify all the individual
parameters. The following table describes how the factor <l> is mapped to <t>, <n>, and <r>.
-wp xpos ypos Same as above, but place the Graphic window in the specified location on the
monitor. Default: window is placed in the center of the screen.
solution_file Solution file to run ray tracing on.
image_file Image file to save the results of ray tracing.
Antialiasing Factor <l> Contrast Threshold <t> Sampling <n> Radius <r>
1 0.0 1 N/A
2 1.1 0 N/A
3 0.0 2 .0.94
4 0.15 3 1.15
5 0.1 3 1.15
6 0.1 4 1.33
Option: Extension: Description: