Compositing with Shadows Does Not Work Correctly

[todd_davis]

I have a simple scene with a robot in 3ds Max and a ground plane with a wrapper material applied to it, to catch the shadows for compositing. In 3ds Max it renders correctly;



the alpha channel looks good too;



Saved this image as a PNG, but when I drop the clip into Premiere Pro, or even when I open it in Photoshop this is the result;



the robot looks way too bright and the shadows are no longer a nice subtle dark color. They're completely white. These are the settings for the wrapper material...



I have never been able to get shadows using the wrapper material with VRay to composite correctly. Any ideas what's going on here? Am I missing something?

[hermit.crab]

Try setting the Background color to black and re-render.

[vladimir_krastev]

Hi, thanks for posting. From first glance it looks like you have a gamma issue. I am not sure if the png is saved with a wrong gamma or something gets mismatched when you open it in Photoshop.
Why png? Have you tried to use exr format? It is a better workflow in most cases.

[todd_davis]

Vladimir & Aleksandar...
Thank you both for the reply and help. I did think that it was a gamma issue or maybe incorrect color space setup in 3ds Max or Premiere Pro.

Turns out it was the Background color. It was set to a mid grey value of 186. Once I switched this to black the shadows saved and composited correctly. Problem solved!

One thing I am curious about, if I have a simple scene with a plane, teapot on top and a dome light. The shadows render the same no matter what color the background is set to. Why does the background color seem to matter when using the wrapper material and compositing?

[hermit.crab]

One thing I am curious about, if I have a simple scene with a plane, teapot on top and a dome light. The shadows render the same no matter what color the background is set to. Why does the background color seem to matter when using the wrapper material and compositing?

It does happen. Maybe you need to render a larger resolution and in post set a darker background so that the border is visible and the shadows are lighter.