Light artifacs - Why....[solved]

[cogombo]

Hi all. I have some problem with this scene. You can see a light artifact behind the furniture. How can avoid this?
I use IM + LC and I tried to avoid it unsuccessfully. But if I charge a preset the artifact is gone.
Thanks a lot :D

http://aycu29.webshots.com/image/28508/2002658825659659619_rs.jpg

[stefan]

either you have a gi miultiplier more than 1 or your material gives more than 100% reflection.

maybe post a file, without seeing it it is hard to tell.
cheers
stefan

[cogombo]

Thanks Stefan.
Here is the file: http://rapidshare.com/files/60856272/Light_artifacs.rar.html
This happens with and without reflection in the material.
My GI multipliers are always 1. I never change these values.
The artifact is more visible if you render in the picture viewer.

Cheers

[stefan]

i look into this,

cheers
stefan

[stefan]

ok, have it
either lower the sample size of the lc in this case, or use brute force.
this is cause the pink is very strong/intense (rgb red =255) and quite near to wall. therefore it needs smaller sampes. so you need a bit more detail in this small area.

(most easiest and savest way always is to use ir-3/-2 and brute force.)
for lc i used 1000 and sample size 0.02 then it renders fine too.

cheers
stefan

[cogombo]

Ok, thanks. Lowering the sample size of LC to 0.01 I can avoid this completely.

I don't like to use Brute Force because it renders slower than LC and the results are more dirty.

An example:

Brute Force: Subdvs.: 8, Ray Depht: 20: Rendertime: 3 min

http://aycu14.webshots.com/image/27933/2000819580022854923_rs.jpg

Light Cache: 1000, 0.02 1:45 min.

http://aycu31.webshots.com/image/31510/2000888462519155797_rs.jpg


About the pink material, I tried to reduce the red value since to 140 and this light artifact remains with a "high" screen sample size (0.05).

[stefan]

brute force normally doesnt render noise, yout leave it at standard values.
but LC is good too of course.(i personally like the brute force)

cheers
stefan

[cogombo]

Ok, I found the problem! The walls must ve volumetrics, not thin planes, as in my case. Here is the example:

Here the wall with the light artifact consist only in a single polygon.

http://aycu19.webshots.com/image/31138/2005341651437562257_rs.jpg

Now I extruded this wall (note the typical spot artifacts at top of the door produced by overlapping polygons). The artifac is gone!!

http://aycu12.webshots.com/image/29011/2005375718944222387_rs.jpg


I found this solution testing with bump. It needs too that que walls would be volumetric.