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.SH NOTES |
| 113 |
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Users should seriously consider using |
| 114 |
|
.I rpiece(1) |
| 115 |
+ |
for multiprocessing |
| 116 |
|
when irradiance caching is employed with a shared ambient file. |
| 117 |
|
If |
| 118 |
|
.I rtpict |
| 119 |
< |
is used in multiprocessing mode with a shared irradiance cache, |
| 120 |
< |
it is trying to compute almost |
| 121 |
< |
the same part of the same scanline in different processes, which |
| 122 |
< |
results in many redundant calculations. |
| 123 |
< |
The |
| 124 |
< |
.I rpiece |
| 125 |
< |
program avoids this by working on separate tiles in each |
| 126 |
< |
process, with less overlap in the indirect irradiance calculation. |
| 127 |
< |
Either program will benefit from an "overture" run of a |
| 128 |
< |
single-process rpict to create the ambient file using a low-resolution |
| 129 |
< |
rendering that is discarded, but this will not completely solve the |
| 130 |
< |
problem for |
| 131 |
< |
.I rtpict. |
| 119 |
> |
is used with |
| 120 |
> |
.I \-n |
| 121 |
> |
greater than 1, it tries to compute neighboring parts |
| 122 |
> |
of the same scanline in different processes, which can |
| 123 |
> |
result in many redundant calculations and cache entries. |
| 124 |
> |
.I Rtpict |
| 125 |
> |
will automatically run a randomly-ordered overture calculation |
| 126 |
> |
to mitigate this problem, but it is not a perfect solution. |
| 127 |
> |
.I Rpiece |
| 128 |
> |
avoids redundant cache calculations by working on separate tiles in each |
| 129 |
> |
process, which brings other benefits as well, such as enabling the |
| 130 |
> |
.I \-ps |
| 131 |
> |
option for image plane sampling. |
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|
.SH AUTHOR |
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|
Greg Ward |
| 134 |
|
.SH "SEE ALSO" |
