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<H1><A ID="SECTION00260000000000000000"> Statistics Reporting</A> </H1>
<P> ! As it is working, informs you of its progress by writing messages to a ``report file''. By default, the report file is the standard error. The report itself consists of a number of progress report lines consisting of the number of eye rays traced, *************** *** 221,235 ****
<P> If a pixel is not sampled at the proper rate, aliasing will result. Aliasing usually appears as ``jaggies'' or ``stair steps'' in the image. ! In order to reduce these and other artifacts, provides an adaptive jittered antialiasing scheme that attempts to detect where increased sampling rates are needed. In jittered sampling, the location at which a sample is taken is perturbed by a random amount. This perturbation reduces aliasing but adds noise to the image. Appendix B describes how jittered ! time sampling is implemented in <EM>rayshade</EM>.
<P> ! The adaptive sampling scheme implemented in begins by sampling each pixel on the current scanline once. For each pixel on the scanline, the contrast between it and its four immediate neighbors is computed. If this contrast is greater — 222,236 —-
<P> If a pixel is not sampled at the proper rate, aliasing will result. Aliasing usually appears as ``jaggies'' or ``stair steps'' in the image. ! In order to reduce these and other artifacts, provides an adaptive jittered antialiasing scheme that attempts to detect where increased sampling rates are needed. In jittered sampling, the location at which a sample is taken is perturbed by a random amount. This perturbation reduces aliasing but adds noise to the image. Appendix B describes how jittered ! time sampling is implemented in .
<P>
! The adaptive sampling scheme implemented in begins
by sampling each pixel on the current scanline once.
For each pixel on the scanline, the contrast between it and its
four immediate neighbors is computed. If this contrast is greater
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*** 263,269 ****
assign a color to a pixel. Ideally, when performing filtering
for a specific pixel,
the filter will consider samples from neighboring regions. In
! <EM>rayshade</EM>, the filtering applied to a pixel makes use of samples
taken for that pixel alone. However, one may increase the size
of the filter that is applied in order to approximate the results
a more robust filtering scheme.
— 264,270 —-
assign a color to a pixel. Ideally, when performing filtering
for a specific pixel,
the filter will consider samples from neighboring regions. In
! , the filtering applied to a pixel makes use of samples
taken for that pixel alone. However, one may increase the size
of the filter that is applied in order to approximate the results
a more robust filtering scheme.
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*** 271,286 ****
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! The default filter width is 1.0 for a box filter, 1.8 for a gaussian
filter. The filter and pixel centers always coincide.
When sampling a pixel, samples are taken over the area of
the pixel filter, which is not necessarily the same as the area
of the pixel itself.
<P> ! Jittered sampling is used in to sample extended light sources as well. A total of <I>samples</I><SUP>2</SUP> samples are taken of each extended light source in order to determine the extent of shadowing.
<P>
— 272,287 —-
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! The default filter width is 1.0 for a box filter, 1.8 for a Gaussian
filter. The filter and pixel centers always coincide.
When sampling a pixel, samples are taken over the area of
the pixel filter, which is not necessarily the same as the area
of the pixel itself.
<P> ! Jittered sampling is used in to sample extended light sources as well. A total of <I>samples</I><SUP>2</SUP> samples are taken of each extended light source in order to determine the extent of shadowing.
<P> *************** *** 295,301 **** to the final picture; if it is not allowed to grow far enough, this premature tree pruning may be evident in the image.
<P> ! <EM>Rayshade</EM> provides two complimentary methods for controlling the depth of the ray tree. One method sets an absolute maximum for the tree. The other allows one to adaptively prune a tree as it grows so that ``unimportant'' rays are not spawned. — 296,302 —- to the final picture; if it is not allowed to grow far enough, this premature tree pruning may be evident in the image.
<P> ! provides two complementary methods for controlling the depth of the ray tree. One method sets an absolute maximum for the tree. The other allows one to adaptively prune a tree as it grows so that ``unimportant'' rays are not spawned.
<P> Index: Doc/Guide/objects.tex *** old/Doc/Guide/objects.tex Mon Feb 3 12:49:56 1992 — new/Doc/Guide/objects.tex Fri Jan 17 10:29:15 1992 *************** *** 1,6 ****
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