Backplate rendering with correct environment reflections

[Lagom]

How do I set up a ground plane backplate camera projection like in Vray so that I obtain correct reflections of objects placed on the ground plane as shown here https://forums.chaosgroup.com/forum/v-ray-for-3ds-max-forums/v-ray-for-3ds-max-general/60219-correct-workflow-if-cg-object-integration-onto-backplate#post680958?

Thanks!

[KristofDeHulsters]

If you are using a backplate I don't think it is possible to give you accurate reflection because it has no way of ray bouncing reflections of the backplate since it is not geometry. Using an HDRI would allow for this as the image incapsulates the object(s). If it is possible to do what you are asking in Keyshot, I'd love to know!

[Lagom]

Thanks; I have not yet discovered a way to do in Keyshot what one does so easily in Vray. I was hoping it is possible here also, as it is essential that products with reflective surfaces reflect the ground plane (camera projected backplate) they are placed on, like the good old teapot example I linked to shows.

[HaroldL]

Is this what you're after"

[Lagom]

Yes and no ; )

I need to use various 4k backplates (focal length, ISO, aperture and f-stop are provided) and a matching high-res HDR image, but can't figure out how to do a camera projection of the backplate on the ground plane, as it is usually done in Vray or Octane. In your case, it appears as if you are solely using an HDR image but no backplate to match focal length and DOF to.

[Lagom]

Bump.

Any other ideas how to translate the Vray approach into Keyshot? Just found out one can do it in Arnold also. Any Keyshot gurus know the trick how to do it here? Without reflections from the backplate camera-projected on a shadow-catching ground plane, there is no photorealistic integration with backplates possible : (

[Lagom]

Bump. Anyone with a way to do it?

[KristofDeHulsters]

Lagom, you should probably bring this up to Keyshot support. I don't think this is possible at all with the current Keyshot generation. It might be something that can be implemented in the future though. One more shot: maybe you can make your image into an HDRI for the reflections, render with transparency so you can have your object without the background, then apply your background in post. That's the only thing I can think of to approach the effect you want.