This question is related to: http://blender.stackexchange.com/questions/67346/where-do-the-white-lines-come-from-in-my-composite

The solution in the above link solves for 2 render layers. I am trying to find a more generic solution that can be applied to any number of Render Layers. Below is the node structure of a shoe model that has 4 Render Layers. I have tried many variations and the closest that I could get is the one below:

node structure

To give a context, the above node structure renders masked images of shoe parts. These images are then used by a web application, which stitches and displays to the user.

The problem that I am facing is, when the images are stitched, a Halo / transparent line / border appears in between the stitched areas. For instance, I am getting a gray border inbetween 2 stitched images as shown below:

Gray border

Is there a generic solution that can get rid of the border issue, which can be extended to any number of render layers.

  • 2
    $\begingroup$ Please provide details about your case, including node setup and actual renders. Maybe related - blender.stackexchange.com/questions/67346/… $\endgroup$
    – Mr Zak
    Commented Mar 19, 2017 at 11:42
  • $\begingroup$ Sorry for the delayed reply. Yes @MrZak. My question is related to the one you have linked to. That answers for a model with 2 Render Layers. I am trying to extend the solution for 7 render layers. But stuck with the nodes interlinking. Looks like the solution works only for 2 render layers. $\endgroup$
    – bot4u
    Commented Sep 16, 2017 at 2:53
  • $\begingroup$ It's not clear where the problem is. Edit your question with explantion and screenshots of where are you stuck. It should be possible to continue node network further with the same nodes as shown there, although exact solution depends on your current setup. $\endgroup$
    – Mr Zak
    Commented Sep 16, 2017 at 8:41
  • $\begingroup$ @MrZak, I have edited the question as per your comment. Please take a look. $\endgroup$
    – bot4u
    Commented Sep 27, 2017 at 7:13
  • 1
    $\begingroup$ The line looks like ambient occlusion to me. $\endgroup$
    – dr. Sybren
    Commented Sep 27, 2017 at 10:45

1 Answer 1


You're in the right track, but the implementation is wrong.

Your screenshot shows that you're combining pairs of plates together, and mix the result with an alpha over node, and that's not correct. What you have to do here is add ALL the plates together.

So, let's say you have your renderlayers A, B, C and D.

What you need to do is add A+B, then add the result to C. The result of A+B+C has to be added finally to D.

The same goes for the alphas.

Instead of that yo are doing A+B, then C+D, and alpha over the result of one on the top of the other, which is wrong.

Start over, remove ALL the alpha over nodes, only use adds. The only node that is not an addition you should use is only one set-alpha node, to assign the added alphas to the added RGB.


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