View Full Version : very frustrating illumination

12-14-2006, 11:25 PM
whatīs the problem with my illumination!? I tried everithing but I canīt avoid to have these white spots on the top and on the windows.....:sad:
I have an area light (with no shadows) and an infinite light (with area shadows) and columns and roof are modelled by extrusion from the same piece

Spots appear:

- with both the lights
- with or without GI (150%, accuracy 90%, 1000 samples, min 200 max 250)
- with or without AO
- shadows accuracy 100%, samples up to 1000 for min and max



12-14-2006, 11:30 PM
Are we looking at a multipass render? If so show a render that isn't the composite of the multipass.

The most likely cause for the pixels is your shadows, the easiest solution is to just add some geometry so that your walls and windowframes have some thickness to obscure the shadow bias. If your'e using shadowmaps on any of your lights modify teh shadow bias settings there too.

12-14-2006, 11:52 PM
thanks for your reply. No, itīs no multipass, only the model without applied materials (the problem remain with materials). I post two shots, with area light on and and another with infinite light on.

12-15-2006, 01:01 AM
I've also had this problem before (light leaking through single poly intersections). Attached is an image of 2 cubes intersecting and 2 single polys. Notice the light leaking only on the single polys.

As Per-Anders suggested, I'd add geometry.


12-15-2006, 01:21 AM
As a quickfix and id the renders will be internal only, you can place a cube surrounding your room with a hole cut into to allow windo wlight in. Get it as tight to the window edges and room extremes as you can. This should stop your light leaks messing up your render.

12-15-2006, 01:30 AM
I don't see a phong tag for the structure.
If there is one take the angle down to 20%
from the default 60-80.

Also, select those edges and add a small bevel
(adding geometry)

12-15-2006, 07:18 AM
thanks guys

Naturally adding geometry works well but the problem is that sometimes itīs too complicated to do (not in this case but I would like to find out something definitive and I would like to understand why a software that we think quite perfect is sometimes so imperfect).

The phong tag make nothing.....
Surrounding cube: it seems to work and produce a reduction of spots, not perfect but much better. As suggested by Heathivan, the problem appears with intersecting polys, modelling beams and roof with different closed objects produce big improvements.

12-15-2006, 08:57 AM
Make a black box around your building to avoid leakage ...
like Janine does it in her 3D Fluff GI DVD ...

the window front has to be cut out of course


12-15-2006, 09:58 AM
You can give temporary solidity to no solid objects using the explosion FX deformer - make sure that you set the time to 0% and you can adjust the cluster thickness (positive or negative) until you don't get light leakage. If all your polygons are facing the same way then it shouldn't affect the appearance of your interior. Even thin solid objects can allow light to leak with soft shadows.

12-16-2006, 02:39 PM
I think you could also add thickness with ClothNurbs, setting subdivison to 0 then setting the thickness... The normals would all have to be alligned...

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