mask layer gap

[WeirdoCello]

I made a test render for a scene, in which the 1st layer (the ground and rock formation) are masking the others. However, for some reason, it started showing a little alpha around some of the objects (the sword and the tree on the left): https://66.media.tumblr.com/69e55d517859a494895cb8a59bc3e298/tumblr_o9p7bjQ7Wc1us7rh4o1_1280.png

Not sure what caused it, or how to fix it.

[Pte Jack]

Maybe increase the overspray in the texture to ensure the entire UV is covered. Check the UV image and see where the overspray stops. You may have to go for a higher resolution texture if the pixels are overlapping into another mesh or increase the distance between islands if you aren't getting the result you're looking for with the overspray.

[WeirdoCello]

Originally posted by Pte Jack:

Maybe increase the overspray in the texture to ensure the entire UV is covered. Check the UV image and see where the overspray stops. You may have to go for a higher resolution texture if the pixels are overlapping into another mesh or increase the distance between islands if you aren't getting the result you're looking for with the overspray.

I don't know what overspray is, and can't find anything mentioning it.

[Pte Jack]

Overspray is the paint on a texture that goes outside the actual uv layout. Most paint programs will fill to the UV line and stop, and because of the program using pixels to fill in the UV some of the alpha will break into the UV area (especially if the anti-aliassing is turned on...

Look at this picture, it's a hair texture that is suppose to have alpha so it's not really the best example but one I have handy.

The top arrows show how the paint passes outside the UV mesh, that is overspray... The bottom arrows point to areas that the alpha flows into the mesh and it causes transparency on that part of the mesh.

If you zoom in close on the picture, you can see individual pixels that form jagged lines where the paint stops and the alpha begins. If these jagged lines are on the very rim of the UV, it can cause proplems like you mention. The paint stops just before crossing out of the mess and the alpha begins. That is where overspray comes in, the overspray allows you to completely fill the mesh with paint before the alpha begins.

http://i.imgur.com/a40dn5p.png

[WeirdoCello]

Thanks for filling me in. Always useful to build up termilology. However, that's not what's happening here. I am using an alpha-transparency such as that hair texture for the leaves on the trees. However, I made sure to not have any leaves show in front of the ground, such that they would mask their entire mesh and show a rectangle of alpha around the leaves. However, the tree trunk and sword have no such transparency. Thus, when masking their mesh in front of the ground, there shouldn't be any alpha gaps, such as this earlier render: https://65.media.tumblr.com/8309fc7a8832e21b33ff6477e3045cc2/tumblr_o9pa79i8J51us7rh4o1_1280.png

So, for some reason, the layers aren't matching up in those areas around the mesh.

[Pte Jack]

Sorry, really dark and hard to see. Are you talking about the blade disappearing, like in the red box here?

http://i.imgur.com/70QUuHb.png

[WeirdoCello]

It's these edges, here: https://66.media.tumblr.com/4d3fbb0f0da3a22342e4e26c52c9c69f/tumblr_o9pe53SEqm1us7rh4o1_1280.png

It may be hard to see because alpha can show up in either black or white depending on what program you're using. I'd post a screenshot from blender with the gray and black checkers, but since posting this,I've done another test render with volumetric scattering to create fog. This time, there are no such edge issues.

[Pte Jack]

So your problem is solved then? Are you using Blender to render these pictures and is it Blender Render or Cycles if yes?

[WeirdoCello]

I don't know if it's solved. I don't know what caused it this time, and I can't garantee it won't happen again. I rendered in Blender Cycles.

[Pte Jack]

ahhh, then I'm going to have to bow out of this discussion, I haven't made the leap yet. Nodes Scare me.... lol