Background image sampling

[david.anastacio]

Hi,

Old annoying thing about the VFB color sampler, it doesn't read background image values. Since we now have a new VFB with V-Ray 5, could we have color sampling enabled for the background images?



Best,
David.

[yavor.rubenov]

Hello,

The color sampler in the new VFB reads the background image when showing corrected colors.

Best regards,
Yavor

[david.anastacio]

Hello,

The color sampler in the new VFB reads the background image when showing corrected colors.

Best regards,
Yavor

Hi,

Can you make that also work for raw values, we never ever use corrected values. We are always switching between several view transforms, so the only constant is the underlaying raw values.

Best,
David.

[yavor.rubenov]

The raw value mode only reads from the rendered image data and doesn't apply any of the VFB layers.

[david.anastacio]

The raw value mode only reads from the rendered image data and doesn't apply any of the VFB layers.

That part was obvious, it's only working for rendered data. What I was asking was if that can be changed to also display the data from the BG image. At the moment here all, artists are not very happy with the current BG image implementation in Houdini, so we don't even use it at all, we currently just draw cards and put the image there so we can get color sampling (raw values) and color management, plus the artists were always complaining of having to use the BG image slot in the ROP instead of the VFB (of course that there are advantages of using in the ROP, but it's counter intuitive and there were even several threads of users complaining about it).
You can just say no and leave it as is, but the way it currently works does not help the people that use it everyday, raw color sampling seems like a small ask to be honest and would help anyone doing lighting and using plates to match that lighting to.

Best,
David.

[yavor.rubenov]

The problem is that the BG layer in the new VFB is just another layer in the stack - you can have multiple BG layers, you can have them in various combinations (blended with others, added only in some folder that affects a certain render element) etc..
All that makes sampling only that layer in the general color sampler a bit problematic.
What if we add a dedicated sampler in the BG layer itself - something like the sampler in the curves layer ?

[david.anastacio]

The problem is that the BG layer in the new VFB is just another layer in the stack - you can have multiple BG layers, you can have them in various combinations (blended with others, added only in some folder that affects a certain render element) etc..
All that makes sampling only that layer in the general color sampler a bit problematic.
What if we add a dedicated sampler in the BG layer itself - something like the sampler in the curves layer ?

Side note here, the expanded compositing capability of the VFB is not useful for us, adding several BG images, color correcting renders, etc. Those functionalities are the responsibility of the compositing department, our renders are not allowed to be color corrected or manipulated in any form in the VFB. We are dealing with hundreds of shots in a show, and need consistency above all, and having artists make adjustments to renders in the VFB won't do, all adjustments need to be made in the 3d scene so they can render correctly out of the box. So that whole new layer and corrections panel is not something we'll be using.
With that said in our scenario all we need is the color sampler to read out the top most pixel raw value of any BG layer in the VFB, and with your complex layer system I can see how hard that can be and I guess it might just be easier to use cards or custom environment nodes with the BG image there, both this methods provide raw values sampling and color management.

Thanks anyway.
David.

[Dubbie99]

We are also in the same situation as David. We never use any of the compositing options. But raw value sampling of the BG is something we would use a lot if it worked.

[yavor.rubenov]

So would something like that work:

We can put the picker directly in the background correction and make it sample only the background image itself.

[david.anastacio]

So would something like that work:

We can put the picker directly in the background correction and make it sample only the background image itself.

Hi,

Am I seeing this right, we would need to use the curves adjustment to go sample the background? If that's the case, no, that's super convoluted.

[yavor.rubenov]

As I said - we can put the same picker in the background layer so no need for curves.

[david.anastacio]

As I said - we can put the same picker in the background layer so no need for curves.

OK, sorry that wasn't super clear the way it was written. That drops it to semi convoluted, would still prefer to just have it on the normal color picker read out in the bottom, but that seems to be impossible.
Would't it be better to always use the bottom color picker read out and then it samples which ever layer you have highlighted in the layer panel? That way you can choose the Source RGB to sample the 3d data, or each individual Background layer to read. What do you think Dubbie99 ?

Best,
David.

[Dubbie99]

David, that suggestion seems good to me.