# Raytracing + Nonlinear Subdivision Level + Surface with Edges draws too many edges

**URL:** https://discourse.paraview.org/t/raytracing-nonlinear-subdivision-level-surface-with-edges-draws-too-many-edges/5648
**Category:** Development
**Created:** [October 24, 2020, 5:02pm UTC](https://discourse.paraview.org/t/raytracing-nonlinear-subdivision-level-surface-with-edges-draws-too-many-edges/5648 "2020-10-24T17:02:24Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![GregVernon](https://discourse.paraview.org/user_avatar/discourse.paraview.org/gregvernon/32/1494_2.png) [@GregVernon](https://discourse.paraview.org/u/GregVernon)
#### Post date: [October 24, 2020, 5:02pm UTC](https://discourse.paraview.org/t/raytracing-nonlinear-subdivision-level-surface-with-edges-draws-too-many-edges/5648/1 "2020-10-24T17:02:24Z")

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When showing the element edges (i.e. render as `Surface With Edges` ) and increasing the `Nonlinear Subdivision Level` from 0 -\> 4, the render facets’ edges are being drawn when using raytracing. I made [an issue for this over on GitLab](https://gitlab.kitware.com/paraview/paraview/-/issues/20245).

I’ve verified this on both Windows and Ubuntu 20.04 running ParaView 5.8.1 from installers. Graphics card is RTX 2060 SUPER.

Here’s what should happen with the attached Exodus file (quadratic hexes):  
[sphere\_hex27.e](https://discourse.paraview.org/uploads/short-url/4p8b1jPejYPfnbQPpYpY5LydjnN.e) (22.8 KB)

 ![image](https://discourse.paraview.org/uploads/default/original/2X/1/196e0b688addb35e0a613b57430db64a520f40d6.jpeg)

Here’s what’s happening when using RayTracing

 ![image](https://discourse.paraview.org/uploads/default/original/2X/1/125856e6394c93229b8e4c2a1d39d595c9a27aaa.jpeg)

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### Author: ![Dave\_DeMarle](https://discourse.paraview.org/user_avatar/discourse.paraview.org/dave_demarle/32/27_2.png) [@Dave\_DeMarle](https://discourse.paraview.org/u/Dave_DeMarle)
#### Post date: [December 23, 2020, 9:35pm UTC](https://discourse.paraview.org/t/raytracing-nonlinear-subdivision-level-surface-with-edges-draws-too-many-edges/5648/2 "2020-12-23T21:35:49Z")

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At a quick glance I think we need to add special case handling for non linear cells in vtkOSPRayPolyDataMapperNode [https://vtk.org/doc/nightly/html/classvtkOSPRayPolyDataMapperNode.html](https://vtk.org/doc/nightly/html/classvtkOSPRayPolyDataMapperNode.html) and its parent class to handle this correctly in the RenderAsCylinders code path.