High discrepancy between irradiance and brute force

[snivlem]

Hi there, I have the above draft image but it shows a huge discrepancy between brute force and irradiance map.

The reason being is the ceiling is made of a VRayBlenMtl. One of the materials is a VRayLightMtl (The square lights) although "Direct Illumination" is unticked.

Just wondering if this is a bug or if this is how it is supposed to work (ie Brute Force seems to acknowledge that Direct Illumination is unticked but Irradiance Mapping seems to ignore??).

My scene is easily fixed but just think I should report this anyway as the difference between renders is very large.

[vlado]

Do you have subpixel mapping enabled for the color mapping? How many subdivs do you have for the brute force GI?

Best regards,
Vlado

[snivlem]

Hi Vlado, yes sub-pixel mapping is enabled.

I have about 30 subdivs on the Brute Force which I assume is bare minimum of subdivs for interiors.

Just surprised at the vastly different outcome

[vlado]

V-Ray does print a warning about that If a significant portion of the illumination comes from a noisy source, the sub-pixel mapping may clip it away which would result in a darker render.

Best regards,
Vlado

[snivlem]

Thanks for taking the time to answer Vlado. I didn't realise Subpixel Mapping could effect it that much - it all makes sense now!

THanks again.