[Radiance-general] running radiance on multiple cores

[Terrance Mc Minn]

I can verify that missing sections of images happens on both Linux and 
MAC computers when an ambient file is used though not consistantly.

Often I have suspected/verified that the number of -N specified is 
greater than the actual number of cores available. For example a i7 
Macbook that a student had in my office 10 minutes ago shows only 4 
cores hence -N 4 would seem appropriate. Some images would complete 
while others left black patches. All I did was to delete the offending 
hdr image and re-issue the rad command exactly to have the image rebuilt 
- much faster as the ambient file has already been populated.

I suspect that the -N number should generally be kept to at least 1 
below the max cores available.

Questions for the Development List :
1) Can multi-core processing be added to trad  (-n for rvu and -N rad)? 
While it is possible to add a -n 4 in the trad options line for rvu, you 
cannot use a -N in the option line for rad.
2) Can the image size resolution for single core processing be the same 
as multi-core to allow further processing with falsecolor. When rad -N 
processing uses rpiece the image size can be modified/rationalised. This 
does not happen in single core processing, hence falsecolor would fail 
when mixing images due to image size mismatch.

Terrance Mc Minn
Lecturer
School of Built Environment
Curtin University of Technology
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