White Outlines around materials

Support Materials and Textures
1

I have been plodding away making an animated giraffe.

On whim I decided to extend my knowledge and add some particle effect hair.

When I rendered I noticed that along the borders where different materials meet a white outline has appeared.

I have searched the forums but not found anything (then again I may have just tried the wrong search terms!).

I have attached a render so you can see it. It runs around the particle hair and also around the scalp.

It may not be related directly to adding particles, I think I may have adjusted something by accident.

Can anyone suggest what I may have done or what i might have to do to fix it?

Anyway, on with the beauty shot:
http://araitanga.com/matprob.jpg

2

There are several things that can cause unwanted outlines or halos. The last time I saw a case like yours it was due to the combination of 2 renderlayers where one layer had “Sky” enabled and the other later was set to “Premul”. More than likely this is where you have gone wrong also. If you want to have a sky, put it in as a post process.
Image textures with lots of noise or jagged transitions will cause Blender to abort antialiasing of the geometry to which the texture is applied and you can often see the alpha matte surrounding parts of the render like aq white halo.
You may have accidentally enabled the “Edge” button on the output tab of the render buttons (F10) or you could have enabled the “Mesh” button on the particles pannel (F7) which will cause the particle emitter mesh to render as a solid along with it’s particles.
Z-combine nodes will also cause render layers to punch through the alpha channels of other render layers (in a very harsh and ugly way) if their respective depth channels have not been antialiased.
Take a look at the release notes on this page: http://blender.org/cms/Render_pipeline.747.0.html
They should help you begin understand the dramatic effect that render order trickery can have on composited images.

3

Hi,
Set ZTransp on the hair material.

4

RawPigeon: Setting all the materials that bordered the “halos” to Ztransp fixed the problem.

RamboBaby: thanks for the indepth analysis of possible problems. I suspect my problems started becasue I am not using a seperate mesh for the particles.

you could have enabled the “Mesh” button on the particles pannel (F7) which will cause the particle emitter mesh to render as a solid along with it’s particles
The giraffe is pretty much one mesh and all I did was group some of the verticies and start particleing where I wanted some hair.To make the giraffe body appear I had to enable the mesh view part. I read the link you gave but most of it went over my head :). Hopefully once I have been going to a bit longer I’ll understand it a bit better (still haven’t quite worked out how nodes fit in to everything).

When using particles for hair is it better practice to use a seperate mesh rather than doing what I have done and group verticies in the existing mesh?