Please more detail on (*) VRayOptionRE: Ability to update the exr metadata parameter in VRayOptionRE with a per-frame MaxScript callback;

V-Ray V-Ray for 3ds Max General
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(*) VRayOptionRE: Ability to update the exr metadata parameter in VRayOptionRE with a per-frame MaxScript callback;
How can I use this?

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Hello!

There is an example at the bottom of our help page Chaos Docs (using animated cameraISO).
Generally, you use the exr_metadata parameter of VRayOptionRe to store custom string that updates on each frame when rendering a sequence. This metadata is saved with .exr raw output and can be read from the rendered images afterwards.

Best regards,
Margarita