White Dots on TG2 Render

[Eric Johannsen]

I'm rendering an OBJ imported from Blender. There are many white spots on edges. What's causing this and how can I avoid them?

I'm using Terragen 2.

[Matt]

It's probably caused by "Unpremultiply colour" in one or more of your Default Shaders (the unpremultiply options are on the Images tab). If you know which shader is responsible for that part of your object, start there.

Matt

[Eric Johannsen]

That did it!

The render doesn't look much different, other than the white dots being gone.

What does unpremultiplied color do? Why is it the default if it can lead to white artifacts?

Thank you for your help.

[penboack]

Try this link for an explanation:
http://www.cgdirector.com/quick-tip-straight-alpha-vs-premultiplied-alpha/

[bobbystahr]

Try this link for an explanation:
http://www.cgdirector.com/quick-tip-straight-alpha-vs-premultiplied-alpha/

so is unpremultiplied colour the same as unpremultiplied alpha ? as that's what the page talks about.

[penboack]

Yes, same thing.

[bobbystahr]

Yes, same thing.

Thanks, confusion lifted.