I get strange borders on my image planes, even if there is a perfect 100% alpha.

Image planes with alpha in a cycles scenery

The rendered output looks like this:

The border of the image plane is visible

I know that this problem was once in the old blender renderer due the "premultiply issue", but now I don't see any premultiply option in cycles renderer.

The node setup is the standard "import image planes" for cycles as shadeless:

enter image description here

Maybe you know a workaround or a setting option in order to fix this?

  • 2
    $\begingroup$ Could you post the earth image you are using? $\endgroup$ – oenvoyage Apr 2 '15 at 15:24
  • $\begingroup$ @Brain can you try making the plane smaller in the UVmap (so it doesn't touch the edges of the picture ) and see if this makes a change $\endgroup$ – Chebhou Apr 2 '15 at 17:49

Seems like there is some aliasing issue with your alpha channel.

I can see two solutions:

Change the texture interpolation from Linear to Closest.

enter image description here

If that doesn't work try adding a Math node to the alpha channel and set the mode to Greater than and the value to .5

enter image description here

| improve this answer | |
  • $\begingroup$ Thanks a lot! Changing the texture interpolation from Linear to Closest solved the problem. $\endgroup$ – Brain Apr 3 '15 at 9:17

Your transparency must be set to absolute white.

Set the color to full white manually, even if it looks white. Inspect carefully.

You (may)have a default RGB value of .8, .8, .8

Light Gray may look deceptively like white.

Change to 1.,1.,1.

Picture to follow

| improve this answer | |
  • $\begingroup$ My picture has already a perfect 100% alpha. The problem was solved by the solution provided by cegaton, changing the texture interpolation from Linear to Closest. $\endgroup$ – Brain Apr 3 '15 at 9:19

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