[Radiance-general] running radiance on multiple cores

[Gregory J. Ward]

Quick follow-up to this...  I did add a slider to trad to control the number of processes.  It's checked into the latest HEAD.

Regarding falsecolor and image size, I recommend using pfilt to correct the image size on the way in.

Cheers,
-Greg

> From: Greg Ward <gward at lmi.net>
> Date: May 23, 2012 9:45:49 PM PDT
> 
> Yes to #1, no to #2.  This was discussed before, and I added a warning from rpiece when the resolution changes, but I can't keep it from changing.  Rpiece (rpict really) needs the tiles to be of equal size, which means both dimensions must be multiples of the respective number of tile divisions.
> 
> You can work around the problem with some difficulty by noting what rpiece changes the resolution to and making sure you set -x and -y to this with -pa 0 on any other runs you do.  Unfortunately, the actual resolution will change with different -N settings because rad will make a different number of tiles to optimize processor loads.
> 
> Regarding #1, I haven't changed trad in ages, so it may take a while to remember enough Tcl/Tk to add this.
> 
> Best,
> -Greg
> 
>> From: Terrance Mc Minn <t.mcminn at curtin.edu.au>
>> Date: May 23, 2012 9:28:34 PM PDT
>> 
>> 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