Render regions with alpha has white outline

[timAugustine]

Hi all,

My scene has a grassy foreground and some hills in the background. I'm rendering the grass separately with the alpha turned on. When I overlay the grassy layer on top of the mountains, I'm getting this weird white outline. Is there a setting I'm not aware of right now?

Render with the white outline

Render

Here are the settings I'm using:

Settings

Thanks in advance for any response!

[Andreas_Resch]

That seems to me an Premultiplied Alpha problem. I use an Alpha Convert node in the Compositor to fix that.

[timAugustine]

Thank you! I will try this tomorrow

[timAugustine]

Hi,

Is this something from a version of blender without Octane? When I try to bring up the covert alpha node I keep getting errors with the word Octane all over it. Even after I select Cycles as the renderer. Is there a way to do this within octane settings?

[Andreas_Resch]

Works in the custom build 28.9 Prime version.

[timAugustine]

I must have done something wrong. It works for me now. And it also fixed the issue for me. Thanks again!

[timAugustine]

Hi, I have another question about this! Is it possible to set the output images to be premultipled directly in Octane? Just curious!

Thanks

[timAugustine]

I didn't find it under blender export, but I did find it under the octane export subsection. It was available only for exr export options (not for png)

[timAugustine]

Once again, this website convinces me to do something better. Thanks!

I'm aware of some of the advantages of .exr usage but I've been hesitant to use them because I'm not very proficient with tools such as da vinci resolve.

Thanks again!

[timAugustine]

Really loved fusion till I found it's 300 dollars, haha! I did look around and found that fusion 9 is free (for some reason I'm not complaining about). I'm not sure if it's any good as the current version is 18. I looked up Nuke and that's expensive as well.

I'll try to make it work with Fusion 9 and if not, I guess I'll try davinci. Are there any other software that you'll recommend?