# Edge rendering issues

**URL:** <https://discourse.vtk.org/t/edge-rendering-issues/7175>\
**Category:** Web\
**Created:** [November 15, 2021, 7:35am UTC](https://discourse.vtk.org/t/edge-rendering-issues/7175 "2021-11-15T07:35:07Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![a-u](https://discourse.vtk.org/user_avatar/discourse.vtk.org/a-u/32/3325_2.png) [@a-u](https://discourse.vtk.org/u/a-u)\
**Post date:** [November 15, 2021, 7:35am UTC](https://discourse.vtk.org/t/edge-rendering-issues/7175/1 "2021-11-15T07:35:07Z")

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Hi there,

I’m struggling with the following problem - model edges are not rendered properly in concave regions. Is there something I’m missing here (like a setting that can be tuned) or is it some kind of an intrinsic limitation?

 ![image](https://discourse.vtk.org/uploads/default/original/2X/3/351d84fed69a3c8cd2584b4298c1758d382c8e08.png)

For completeness I attach the vtkjs scene:  
[94c1ac82-cf36-11eb-af7f-00e04c680268.zip](https://discourse.vtk.org/uploads/short-url/33j8Gsf3huBB6H0Ak5YglqY7CTt.zip) (3.8 KB)

Best,  
Adam

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**Author:** ![finetjul](https://discourse.vtk.org/user_avatar/discourse.vtk.org/finetjul/32/154_2.png) [@finetjul](https://discourse.vtk.org/u/finetjul)\
**Post date:** [November 15, 2021, 7:36am UTC](https://discourse.vtk.org/t/edge-rendering-issues/7175/2 "2021-11-15T07:36:24Z")

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Have you tried playing with ResolveCoincidentTopology on the mapper ?

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<div class="post-metadata">

**Author:** ![a-u](https://discourse.vtk.org/user_avatar/discourse.vtk.org/a-u/32/3325_2.png) [@a-u](https://discourse.vtk.org/u/a-u)\
**Post date:** [November 15, 2021, 7:29pm UTC](https://discourse.vtk.org/t/edge-rendering-issues/7175/3 "2021-11-15T19:29:07Z")

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Thanks! With `mapper.setResolveCoincidentTopologyToPolygonOffset();` it does get better (see below), but some other glitches become visible. Do you have any idea how to get rid of them?

 ![image](https://discourse.vtk.org/uploads/default/original/2X/f/f222b574c5d5416f4b74eb87f5165e128ee220f5.png)

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<div class="post-metadata">

**Author:** ![finetjul](https://discourse.vtk.org/user_avatar/discourse.vtk.org/finetjul/32/154_2.png) [@finetjul](https://discourse.vtk.org/u/finetjul)\
**Post date:** [November 15, 2021, 10:15pm UTC](https://discourse.vtk.org/t/edge-rendering-issues/7175/4 "2021-11-15T22:15:05Z")

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You need to play with the resolve coincident topology parameters

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<div class="post-metadata">

**Author:** ![a-u](https://discourse.vtk.org/user_avatar/discourse.vtk.org/a-u/32/3325_2.png) [@a-u](https://discourse.vtk.org/u/a-u)\
**Post date:** [November 16, 2021, 7:59am UTC](https://discourse.vtk.org/t/edge-rendering-issues/7175/5 "2021-11-16T07:59:03Z")

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Indeed thanks, this did the trick for me:

```auto
mapper.setResolveCoincidentTopologyToPolygonOffset();
mapper.setResolveCoincidentTopologyPolygonOffsetParameters(0.5,100);

```

I’m not sure what exactly it means, but it seems to be working in my use case.