View Full Version : weird render problem

08-04-2006, 09:59 PM
Hi there. I'm having a weird render problem. I have an object that part of which renders super dark if I render using raytraced lights (or radiosity). If I render the object using all shadow-mapped lights, it renders fine. The problem is I want to render this out with some background radiosity.

Anybody have any idea why this is rendering like this? There are no non-planar polys involved, so I'm at a loss as to what's happening. I've attached a jpg to view.

And here's my specs:

Lightwave v9, OSX v 10.4.7

thanks for your help.

08-04-2006, 10:07 PM
and even if I render it at a renderfarm (respower) I get the same result

08-04-2006, 10:18 PM
Are you referring to the black bars? Could you post your objects/scene?

08-04-2006, 10:23 PM
yep. the black bars are actually slats that should render just like the rest. I've attached a previous render of this scene (a bit different lighting, but you'll get the idea of how it should look rendered.)

08-04-2006, 10:40 PM
I wonder if it's simply a matter of light not reaching inside the slats (too deep). An easy way to find out would be to change to say area lights to soften the shadows and/or increase ambient light.

08-05-2006, 01:17 PM
On the texture for the slats, is the diffuse value really low?
You could try saving the texture on the slats, then copy & paste the texure from the main object walls.
That would at least eliminate or confirm the texture as the problem.

08-05-2006, 03:05 PM
I bet its the light not reaching the inside of the slats just like Sekhar said.
Try putting an extra directional light pointing in the slats direction just for testing purposes.

08-05-2006, 03:27 PM
Could even be a quantisation error, if the slat offsets are much smaller (orders of magnitude smaller) than other parts of the scene. (Or if the area light is teeny)


I get ultrablack shadows if I have objects with very-nearly-zero offsets. If non-planar polys aren't an issue, might co-planar polys be present? Also, if you've got a gloss coat on there in any way, try racking up your ray-recursion limit.