Shadow Catcher - PNG

Corona Corona for 3ds Max General
1

Hello,
Quite some time ago I reported that saving files to PNG’s does not work as expected.

So Examples are but not limited to:

  • Refraction (If your refracted objects have other objects with solid alpha behind them, you will end up with holes in your image)
  • Bloom and Glare (Just ignored by the PNG, unless there is a solid object behind it)
  • Reflection (Ignored on windows due to refraction)
  • Shadow Catcher (Some settings work the same way as Refraction)
  • VDB (Same as Bloom and Glare it’s just ignored)

So my question is, how can I save my files with those effects, but still keep the transparent background?

Image attached is

  • Left regular shadow catcher on a black background to avoid white halos after hundreds of passes loots of noise.
  • Right same image but with “Recieve shadows” option off, at that point shadow catcher is just noise.
    png_noliki.jpg
    png_noliki.jpg670×450 59.1 KB
2

Please, make an exemplary mockup scene with everything set to render - so everyone can help you out & tackle the issue :smiley:

3

Are you sure those things are specific to PNG file format? Have you tried with other formats?
I think most of that comes down to “affected by reflections/refractions” options, like you have in V-Ray. We understand that this is highly demanded, and have it logged.

Other than that - like Burning said, please create simple scenes for each of those issues so that we could easily reproduce them. Otherwise it is hard to understand them (or at least we could easily get confused).

4

Sounds reasonable, will do asap

5

Save the file as PNG or any other alpha type file

all is lost.
Reportanto.max (732 KB)

6

Hey I found few solutions, but non of them are “ok” for me.

Do you have any better ideas than mirroring the objects?

7

So far I only have two findings about your scene:

  1. Yet another bug with glossiness lower than 1
    If you enable reflectivity for the shadowcatcher, and then lower its glossiness, then this “black spot” will appear in alpha of the shadowcatcher. This is definitely a bug, and I will report it*.
    The solutions/workarounds are:
  • Using glossiness 1 for the shadowcatcher
  • Enabling “shadowcatcher illuminator” option for the light
  1. Bloom and glare not considered in alpha
    Currently this is intended. The solution is to:
  • Add CShading_BloomAndGlare render element and enable bloom and glare in its settings
  • Add CShading_Beauty render element and disable bloom and glare in its settings
    This way you will end up with:
  • Beauty with bloom and glare
  • Beauty with no bloom and glare
  • Bloom and glare on black background
  • Alpha with no bloom and glare
    Then you just have to compose your image and put the CShading_BloomAndGlare on top using the Add operation.
    This is probably not very convenient, so it may be improved in the future.

*Issue 1 is actually already reported:
(internal id=173146446)

black-area.png
black-area.png2559×1397 391 KB