[Radiance-general] rtcontrib and ambient cache

[Rob Guglielmetti]

I just checked out the new rtcontrib program, following Greg's examples #2
& 3 in the manpage to create two separate images of sources in a scene and
recombinig them with different values.  VERY COOL.  However, when I run
the command:

vwrays -ff -x 1024 -y 1024 -vf best.vf | rtcontrib -ffc \
         `vwrays -d -x 1024 -y 1024 -vf best.vf` @render.opt \
          -o c_%s.pic -m light1 -m light2 scene.oct

I get the following message:
rtrace warning: zero ambient accuracy so "test.amb" not opened

...but I did have -aa set to .1 (and this is in my render.opt file), and
there is a valid ambient cache.

Two questions:
a) Why is this happening?

b) Is this the only reason for the direct-only component showing up in the
renderings, or is this the intended result of the command?  IOW, I was
hoping to be able to create renderings that showed the net result of a
single light source, but both its direct *and* indirect contributions to
the scene. Can this be done?

-- 
Rob Guglielmetti
www.rumblestrip.org