Picture on a wall: no shadows

[Giovanni]

ok,
try this:

1.start MAX 2010, 32bit, Vista
2. create two boxes, that is, like a wall and a picture frame hang very closwe to it.
3. create a spot light, assign vray shadows, point it at the frame, from mid air.
4. render at a skew angle, so that you see the edge of the picure frame in shadow, in detail.

What I get is no shadow against the wall, and the back of the picture frame actually seems to emit light. If you move the frame away from the wall, everything looks good.
If you tweak the secondary ray bias you can modify the results, but not fix it.

Any idea?

thank you

regards

gio

[Giovanni]

hmmm... shadow bias, default 0.2, set it to 0.1 and fix it.

oh well...

[Morbid Angel]

this will happen if your scene is too small. Shadow bias prevents vray to sample too many rays in the small areas where they might not be seen by eye, thus increase render speed.