Layout Asset Gallery : Thumbnail color don't match

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219 posts
Joined: Oct. 2015

I have multiple problems to create good thumbnail with custom scene :
1) First, thumbnail just can't be generated on actual production build H20.0.625 (error message "unable to write image:" and "Failed to create file")
I check all access and all is good but that just don't work. Anyway it works on "last" daily build H20.0.649

2) I want to generate bigger image but can't go up to 256px.
If I set to 512px or 1024px, rendered thumbnail has always clamped to 256px.

3) Now the biggest problem was when trying to render thumbnail with same look as viewport rendering color (karma xpu). Color doesn't match at all.

Can but subtle but still don't match on all variants.
After investigation I notice that in fact thumbnail was rendered and writed in ACEScg but there is no way to set "color correction" in the "asset layout gallery" pane like in viewport.

There is also no way to directly set a good ocio output color profile to match with viewport render.
How can I acheive good thumbnail to just make them true in color ?

I notice that houdini config ocio has not the "Invert ACES 1.0 SDR-video" output space, like in redshift, that allow direct conversion from ACEScg to simple flat sRGB picture (hope that's clear)

This way it would be easy to set this ouput space inside "karmarendersettings -> Image Ouput -> Output Colorspace" parameter.
The only way was in cops with an "ocio_transformview" node inside a "vopvop2filter" node. But this way make all really complicated.

Have you experience in working with usd layout asset gallery ?
How do you face to all this problems ?

cf. sample project file
Thank you

asset_thumbnail.jpg (216.1 KB)
fusion_srgbAcescg_to_invertAces.jpg (189.9 KB)

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456 posts
Joined: June 2020
If you've not already, can you please log bugs for these issues (ideally one bug for each issue)? That will get this in front of the right eyes the fastest.
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219 posts
Joined: Oct. 2015
Hello @robp_sidefx, Ok I do it right now.
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