Weird alpha bleeding I am trying to render a Minecraft scene generated by Mineways. Quite simply, some of the blocks seem to have transparent edges, as in some cases the "sky" colour (plain blue for now) is showing through while in other areas there are visible "seams" between the blocks, implying that the adjacent blocks are showing through.

In the picture below this issue is most noticeable around the base of the tree in the foreground to the right and along the bank behind the tree (where the blue sky is showing through) and on the logs at the front of the greenhouse (where there are visible "lines" between the log blocks which seem to be caused by the same issue as these lines go away if I turn off the texture's alpha channel). (Don't worry about the weird lighting/shadows - I'm trying to light the scene from inside the greenhouse but have not finished setting up the lighting yet.)


EDIT: Here is the .blend file (ultimately this will be the background for another scene, hence the name background.blend). I would appreciate it if, if you make any changes, you let me know what they are instead of just uploading a modified file.

https://drive.google.com/file/d/0Bzg8zit7X1NALWtPM0RUN0tPdU0/view?usp=sharing

EDIT 2: Here is a .zip file containing both the .blend file and the accompanying texture files. Note that the .blend file in this archive is slightly different to the .blend file above as I had to change the textures to use the correct file path to work when the .zip file is extracted.

https://drive.google.com/file/d/0Bzg8zit7X1NANzN3cGIyUl9tSFk/view?usp=sharing
If you look closely, you can see that this is caused texture interpolation getting a little bit of the alpha surrounding the wood texture. So in other words, your wood texture is outlined with a line alpha less than a pixel wide which lets you see through to the objects and sky behind.



This is why you usually want to have a small margin around UVs so interpolation will have something outside with which to interpolate with besides alpha.

To fix this, you can try using the solutions below individually or in combination.


Scale the wood UVs in a little so the UVs aren't right up against the alpha:


This is really a pretty generous margin for this situation. In this case it only needs to be scaled in about half a pixel, but a little extra can't hurt.

Not completely ideal, as you lose part of the texture (though it's unlikely anyone would notice).
Disable interpolation. It won't completely get rid of the problem, as the texture is still filtered a bit when it's distorted by perspective etc, but it will be so small that it's only visible when viewed really close up. This way you can also save some memory by using the 512x512 texture, as it will no longer be blurred by interpolation if it's disabled.