hey everyone,

i went to render some photon maps tonight and i thought it was odd that i could not use both processors on the machine i was at. it would work fine if i went to render an image or whatever, but i kept getting stream failures when trying to output pmap's..

anyone else having problems with that..?

tia,
dave

Hi deecue,

SESI explained that Mantra renders on 2 cpus by multi-processing and not by multi-threading. Either way has their advantages, but one of them is that certain tasks, like writing to the same file is not possible unless it is tightly managed, as is the case with a tiled/paged image format. Photon map file generation unfortunately is one task that has not been made possible to render with dual CPUs. I remember reading about this somewhere, but it might've been a private mail, or a hallucination.

(correct me if i'm wrong on the facts there, sesi. no comment on the hallucination bit there )

Take care,
J

ahh ok.. that makes sense now..

so do you think it would be possible to use one processor for one frame and the other processor for the next (so each one is writing to their own file rather than the same one)…? maybe something on the lines of odds and evens..

or what if i were to open up another instance of houdini and ran another render while the first was going, would it use the other processor by default or just clog up the first one..? anyway to tell it to use the second one only?

thanks jason.