Frustrating RT(CPU)/Production issue

[Art48]

Hi,

Just sent a .rar file to vlado containing the scene and two renders (one with RT and one with production)
Unfortunately I can't share the renders or scene with the public due to NDA reasons.

In the end it's about some (heavy) brightness differences and I have no clue what's causing it.

It would be much appreciated if vlado can take a look at the scene.

We got some "special" setup in this scene:
1) VRayPlane as groundplane with matte object enabled
2) Environment overrides for reflection/refraction (black) and a white background

I have no idea what's causing the differences and its quite frustrating because lighting with RT is a blast and so fast but if you can't rely on it even in such simple setups its kinda bad.
Maybe I am doing something wrong but I cant think of anything at the moment that would cause this behaviour and since I know RT got its problems i figured it'd be best posting it here.
The core issue is that some reflections render brighter in production than in RT.

While we're on it:
- Camera exposure still has no effect whatsoever in RT so we decided to render completely in RT with exposure off in the end.
- MultiMatte doesn't render masks when in material id mode. Object ids work fine.

System specs and software versions see my signature

[matanov]

It's from the "Sub-pixel mapping".

[Art48]

Hi,

Well I am aware that RT doesn't support subpixelmapping thats why I also tried turning it off and still RT and production don't render the same brightness.
Reason I keep SPM on is jaggy edges even when rendering clamped. I rather have clean edges than a "correct" result

Did you try to render with SPM disabled? RT and Production SHOULD render the same, but it didn´t in my tests...

And by the way I jsut figured out why exposure had seemingly no effect at all: You need to restart RT in order for the camera changes to take effect...that is annoying. Any chance of a fix?

[matanov]

In my test with SPM disabled RT and Prod output the same result. About RT evaluating camera changes - can you tell me which settings are you tweaking ?

[Art48]

Ill be testing SPM again; as for camera parameters it was white balance, f-stop and iso

[matanov]

SPM is also causing the camera update issues, but the fix is already included in the next SP (probably by the end of this year).

[Art48]

Good to know - does the fix include SPM support for RT?

[3DMK]

We got some "special" setup in this scene:
1) VRayPlane as groundplane with matte object enabled

As far as I am aware, VrayPlane is NOT supported in Vray RT.
This may be what's causing the brightness differences ?? It certainly would have a noticeable effect on brightness by loosing a ground plane. I am guessing that RT is brighter??

Hope this helps
Cheers

Jamie
3dmk - Treeline
http://www.3dmk.com.au

[vlado]

We do support the VRayPlane in the latest builds, but I'm not sure what build Peter used in his comparisons.

Best regards,
Vlado

[Art48]

Actually RT is darker than Prod, thats also what's irritating me.
And VRayPlane is only not supported on GPU afaik, in CPU mode it seems to work ^^

Any info on SPM support for RT with next update?