GI Issues

[marcdevon]

I know the problem that I am encountering has probably been addressed before by this group but I do not know what are the proper search terms to find a solution to my problem.

I am attempting to do some lighting test on the scene below. The scene in illuminated by a (invisible) VRay dome light (w/ hdri map) for sunlight, and separate hdri map for diffuse GI skylight:



As you can see, the fascia on the roof seems to not pick up any light. That same can be said for the the porch platform. For the aforementioned, the fascia faces ont he front is picking up some light but it is very noisy. Why is all of this happening? The are other cabin surfaces ,which are parallel to the roof fascia surfaces, are receiving light but the fascia themselves (especially on the sides) are receiving no light.

I will admit that I am still a newbie to VRay but I have read throughout the manual. I decided to use the irradiance cache for the primary bounces and the light cache for secondary bounces. Here are their respective settings:






FYI, here is the same scene rendered without a secondary bounce:




What am I doing wrong?


Thanks

Marcus

[instinct]

looks like co-planar faces. try raising your secondary ray bias to 0.001 and see if that helps.

Thorsten

[studioDIM]

doublefaces a go-go mate
Check the geometry: it looks like Z-fighting for coplanar faces.

Lele

[studioDIM]

both would do, mine is cleaner



Lele

[marcdevon]

Hey guys,

I would have never guessed that was causing the problem. It seems like my architectural modeling software does this (for what reason I don't know). Anyway, I deleted the coplanar surfaces and here is the result:




instinct,

you mentioned raising the secondary ray bias to 0.001. Where is the secondary ray bias parameter located?



Thanks for all of the help,


Marcus

[instinct]

in the global rendersettings.

Regards,
Thorsten

[jujubee]

Two other very important things - DO NOT USE Delone Triangulation. Also, your IRMap settings do not need to be put on high. High settings are often overkill. Max 80 Hsph (although you could probably go with 40) and max 20 Interp.