Rtpict overture

Hi all,

In the newest update at RW2022 @Greg_Ward showed how the rtpict was updated for better parallel runs. I do have a few questions though.

  1. This is only relevant for files that have -aa != 0?
  2. This only works with -af parameter set to a file?
  3. Would I benefit from running a low res thumbnail for overture or is it automatically done? The slides show that it will if “other than a picture is requested” which im unsure what is.
  4. any tricks on the overture setup? just a 300x300 image will do and then same ambient parameters and cache file for a more highres?

Hi Mathias,

The rtpict overture calculation is designed to avoid redundant calculations rather than the traditional use, which is to simply improve image smoothness. It takes place when all of the following are true:

(a) The -n option is > 1

(b) The -ab parameter is > 0

(c) The -af parameter is assigned

(d) The -o* option is used with multiple output files as described in the man page

Without (a), it’s a single process so no shared values. Without (b), no indirect cache, so no need. Without (c), no place for shared data, so an overture does not work. Without (d), rtpict can shuffle the entire list of samples and do a “perfect” job of decorrelating indirect calculations, though there is some added cost in the long call to sort(1) at the end.

Hope that helps!