VRayEnvironment fog changing thickness with GI solution?

[snivlem]

Hi,

I've noticed in a scene I get vastly different results with Environment Fog and different GI solutions - it seems to randomly change thickness;

For example,

Brute Force with Light Cache produces the regular result
Irradiance Map with Light Cache also produces a good result.



Irradiance Map with "Enhance Details" and Light cache with "Retrace Threshold" makes fog like 10x thicker

During these tests the GI caches were frozen.

Unfortunately I have not found out how to reproduce this though - it seems to pop up during region renders

fog.zip

[tashko.zashev]

Hi,

I made some tests with your scene file but can't get any differences between Irr map/LC and Irr map (Detail Enh.) / LC (raytrace htresh.)

I suppose that for your example image there is a difference because of the Brute force Depth parameter set to "1".

[snivlem]

There is something definitely strange going on - I'll try and figure it out fully. But its been hard to reproduce.

Despite my first post I'm getting major discrepancies with just irradiance map, I'll have to rule out Brute Force depth being the cause now.

It's to do with region rendering - but I'm not sure what's triggering it. I'm using DR rendering too.




Two separate render regions - quite clearly there is a significant difference between the fog "thickness" even though I haven't touched anything. (Ignore the pixelated buckets - I cancelled both region renders at around 90%).

For reference, the one at the top part is the correct one (even though it subtle, it's amazing the soft effect it has on GI on interiors so I wish to keep it). Sometimes it just goes to the below render region which is too much.

[snivlem]

Hmm, maybe I just put it down to faulty build - I'm on June 8th Maya x64 2014.

If I zoom in I can see there are discrepancies between buckets; very faint though;





It is far less noticeable when Embree is off. Maybe I try newer build.

(I should note all assets and textures are pointing to our main server and even so transfer missing assets is also ticked with no cache)

[Svetlozar Draganov]

Are you sure that you are using the same Vray build across all slave/workstation machines ?
Have also tried another build ? If yes does the issue still persist ? Also what happens if you set cut off threshold to 0 in Raymarching options?

[snivlem]

I'll try that next, in the meantime a test batch render from render.exe command line, the same scene but two different cameras (both cameras have same exposure)

There is some bizarre discrepancy going on.

[Svetlozar Draganov]

Hello again snivlem

Can you send us some example scenes in order to investigate what's going on?