Black areas in Glass Lightflow Renders

Support Basics & Interface
1

When rendering images using many glass objects, I always get “black” areas where many objects overlap. No matter what parameters I change, I cannot get the “black” area in the render to become transparent or render properly. What am I missing?

Example Interface:
s.newInterface( ‘default’, [
‘displacement’, 0, ‘shadows’, 1, ‘volumes’, 0,
‘processors’, 1,
‘caching’, 1000, 100, 0.100000, 0.300000,
‘trace-depth’, 64,
‘radiosity-depth’, 64, 64,
‘radiosity-samples’, 100,
‘radiosity-threshold’, 0.200000,
‘radiosity-reuse-distance’, 0.250000, 0.400000, 0.010000,
‘lighting-accuracy’, 0.980000,
‘lighting-count’, 1,
‘lighting-depth’, 100,
‘lighting-threshold’, 0.050000,
‘photon-count’, 30000,
‘photon-clustering-count’, 250, 10
] )

Any help would be great because this is driving me crazy.
Thanks

Phil

2

Are your normals all pointing out? Do a recalc normals with ALT+C on all your meshes before you export from Blender.

BgDM

3

I don’t use Yafray, but it sounds, like your max_trace_level (Povray term) is too low.
Try to find such a parameter.

D.

4

Two causes:

1 - Not enought Ray Dept.

Rays undergo a finite number of reflections/transmission. When all are done and still the teoric end of the path is not met, you are out of luck :slight_smile:

2 - Not 100% transparent/reflective materials

At each bounce/transmission you lose energy, sooner or later you have lost all your energy…

Stefano

5

Thanks for the tips, but so far no luck. This is not a normal issue. What I am modelling is thin sheets of glass made from Blenders cube from simple scaling. I have 15 of these vertical, all with 100 % transmission. The lightflow renders look great but after the light gets about 4 or 5 panes of glass in, the rest are rendered straight black.

I tried maximizing the Ray Depth in the Lightflow script and still the same results.

Are there any other parameters that I should change as well such as the light depth or samples?

6

Found elsewhere on Elysiun … might be helpful:

Black objects occur after mirroring an object in object mode. The size of the object changes from SizeX to -SizeX, etc. Blender can’t handle negative sizes in shaded views.

To correct the objects, use “Apply Size/Rot” (Ctrl+A) This will normalize the sizes to 1 and make the local axis parallel to the global axis.

-dl