White border around alpha channel

[nb13ki]

Hi,

I am using 3Ds Max 2019 with the Arnold renderer

I am trying to render a moving object with a transparent background to overlay on a static background. Every time I try to render, the object has a white border around it. The only thing so far that's worked is to use black as the background (no environment map). This is problematic because it changes the lighting of the object and doesn't match the scene.

This is the scene :

This is the foreground, the blue background is just there to show white border

The alpha source of all bitmaps is set to "None (Opaque)"

Any help is greatly appreciated!

[lee_griggs]

EXR may be a better format for compositing, otherwise, you might find something useful here.

[madsd]

Try something like this.

My result in photoshop, the fringes has good integrity towards alpha.

Light comes from a hdri, and I just used the environment switch map, so I could put a pink color in the view background while still having light and shadows come from the actual hdri.

( you dont have these maps in 2019, so just do like you normally do )

Save to .exr format

[nb13ki]

Thanks so much for your quick reply!
I tried installing the environment switcher and HDRI environment OSL plugins, but it didn't seem to work.
I don't think I understand what you mean when you say " do like you normally do".
If I don't have those OSL maps, and just make the environment pink it doesn't really work either. 😞
Also, why did you use pink?

[madsd]

Pink was the random color I picked, it means nothing.

Just add your hdri to environment directly and save out an .exr file, the file format is what is important, how you light it is not.

[nb13ki]

Oh ok.
And yes! That's what I was doing before, just connecting the bitmap to the environment and saving as .exr

But I still get the white border in photoshop

[nb13ki]

I think I figured it out!

In render setup > arnold renderer > environment,background & atmosphere > Background (Backplate)

I changed the source to "custom colour" and set it to black, but like you said, it could be any colour.

It's a little jagged, but works

[madsd]

You also need to set the arnold backplate to either custom shader or arnold shader for Glass to translate correctly in alpha channel.

[nb13ki]

thank you!

[madsd]

It should work right off the bat tho, so I am not sure why you need to force this in.
Except I can see you have raised the background color next to the environment slot to something like grey, leave that color slot alone and let it stand at zero at all times and use other means to get what you want.

[madsd]

Small but vital update on the issue.

It is forbidden to change the background color in the environment panel next to the environment slot.

This is a legacy trace and should be pulled out of the application in the way it works with Arnold, we have plenty of ways to do a background with Arnold directly, but this slot destoys the alpha and edges if you raise it.

I spotted on your extra images you are infact altering this black default to a mid grey and I can reproduce the alpha glitch if I do the same, stuff starts to bleed into the color/alpha leaving you a fringe.

So make sure this slot is set to 0,0,0 completely black.