Author Topic: Glass and backplates  (Read 4103 times)

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Offline NDenekamp

Glass and backplates
« on: June 26, 2015, 12:00:12 pm »
Hi There,

I've noticed a behaviour in Keyshot when working with glass and backplate images that I don't quite understand. This came up when I was testing an HDRI environment on some sample geometry to see the light effect and how it renders out various materials.

With the HDRI I use a matching backplate. Then when I apply a glass material to the spheres, it suddenly renders the backplate refracting through the sphere, and more or less darkness around it.  When I turn off the backplate I see the HDRI refracting through it which looks far more realistic.

I guess if the geometry was a flat plane you would want the prior behaviour, but when the curvature is such that you start seeing the edges of your backplate you might want the latter behaviour. Could it be possible to have a switch between the two perhaps? I don't know how often this comes up but in this case the default behaviour really does not give the desired result.

A fix I found is to render out both can mask out the objects on the backplate render to let the environment render come trough.

Attached are:

Render with backplate showing
Render with environment showing
Composited of the two renders

Offline Arn

Re: Glass and backplates
« Reply #1 on: June 26, 2015, 03:33:12 pm »
Compositing seems to be the logical choice. If you have a limited image with borders, a very pronounced lens is going to show those borders sooner or later. Without changing how the physics work, that will not readily change.