[Radiance-general] rpict can recover, can rpiece?

[Mark Stock]

I am rendering a medium piece (8k x 8k) using rpiece on a
cluster of Opteron processors, and I have used "rpiece -F"
to create the sync file and start 4 processes. I even used
"rpiece -R" to restart the job once. (Thanks to Giulio
Antonutto for helping me get started.)

Anyways, there are two parts of the 64 subdivisions of the
image that are giving me trouble. I invoke them piece-at-a-
time:

% more argsN
-X 8 -Y 8 -t 600 @vp11 @opts -x 8000 -y 8000 -o img13.pic scene.oct

% echo 2 0 | rpiece @argsN
rpict: warning - no light sources found
FRAME 1: -vta -vp 1.3 -1.8 1.1 -vd -0.524211 0.708567 -0.472373
-vu 0 0 1 -vh 5.45455 -vv 5.45455 -vo 0 -va 0 -vs -1.5 -vl -3.5
rpict: 0 rays, 0.00% after 0.000u 0.000s 0.000r hours on str2
rpict: consistency - bad ray direction in inithemi
rpiece: read error from rpict
Command exited with non-zero status 1

I understand the "no light sources" error: I illuminate with
the sky dome only. It's the "bad ray direction" that is causing
me problems.

Now, I had previously seen this error when I rendered a smaller
version with rpict. I simply re-ran rpict with the "-ro" recover-
overwrite option. But it seems that the "rpiece -R" recover
option restarts any incomplete subsections instead of continuing
where rpict left off. So, every time I try to patch the missing
pieces, I get the same error at (presumably) the same place.

So, can rpiece recover in a pixel-wise sense like rpict, or,
how can I find out what command sequence (including rpict and
not rpiece) can render those bad patches and put them in the
final image.

Or, is there any rpiece option that will ignore the "bad ray
direction" error, or mitigate its effects?

Thank you.

Mark