# Visual artifacts at open surface ends when raytracing data in VTU format

**URL:** https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551
**Category:** ParaView Support
**Created:** [July 20, 2023, 1:17pm UTC](https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551 "2023-07-20T13:17:58Z")
**Posts on this page:** 7
**Page:** 1

<div class="post-metadata">

### Author: ![Hendrice](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/h/e274bd/32.png) [@Hendrice](https://discourse.paraview.org/u/Hendrice)
#### Post date: [July 20, 2023, 1:17pm UTC](https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551/1 "2023-07-20T13:17:58Z")

</div>

Dear ParaView-Support,  
I’m currently facing an issue when visualising iso-contours with raytracing. The iso-contours are created in ParaView and saved as .VTU and then loaded again and visualized.  
Without ray-tracing:

 ![raytracing_off.PNG](https://discourse.paraview.org/uploads/default/original/2X/f/f2a9a85e58fba2f05774288bf6f6c02e56def04e.jpeg)  
With raytracing:  
 ![raytracing_on.PNG](https://discourse.paraview.org/uploads/default/original/2X/f/fe74a61323ac0fc0cc11d9b0cb96e70a8fd67de8.jpeg)

Any idea why this is happening and how to fix it?

---

<div class="post-metadata">

### Author: ![ben.boeckel](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/b/ea5d25/32.png) [@ben.boeckel](https://discourse.paraview.org/u/ben.boeckel)
#### Post date: [July 20, 2023, 5:56pm UTC](https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551/2 "2023-07-20T17:56:54Z")

</div>

Cc: @Sankhesh_Jhaveri @Dave_DeMarle

---

<div class="post-metadata">

### Author: ![Sankhesh\_Jhaveri](https://discourse.paraview.org/user_avatar/discourse.paraview.org/sankhesh_jhaveri/32/3374_2.png) [@Sankhesh\_Jhaveri](https://discourse.paraview.org/u/Sankhesh_Jhaveri)
#### Post date: [July 20, 2023, 6:04pm UTC](https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551/3 "2023-07-20T18:04:06Z")

</div>

@Hendrice Does your data have any ghost arrays?

---

<div class="post-metadata">

### Author: ![Hendrice](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/h/e274bd/32.png) [@Hendrice](https://discourse.paraview.org/u/Hendrice)
#### Post date: [July 20, 2023, 7:07pm UTC](https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551/4 "2023-07-20T19:07:02Z")

</div>

Hi @Sankhesh_Jhaveri,  
not that I’m aware of. You’ll find a tiny clip off the data attached, but you can still see the issue when turning on raytracing using the OSPRAY backends.  
[mini\_example\_isocontour.vtu](https://discourse.paraview.org/uploads/short-url/lWvEhPLp9VXK9qcG74Xwas3jqfQ.vtu) (2.6 MB)

To me it looks like PV somehow is rendering the open surface loops as tubes, but the get very large.

---

<div class="post-metadata">

### 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: [July 21, 2023, 1:17am UTC](https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551/5 "2023-07-21T01:17:05Z")

</div>

What happens if you adjust “Line Width” on the Properties tab?

It could be that the [default heuristic used as a radius for the tubes](https://gitlab.kitware.com/vtk/vtk/-/blob/master/Rendering/RayTracing/vtkOSPRayPolyDataMapperNode.cxx#L890) that the ray tracers draw for Line type cells is not good for this data.

---

<div class="post-metadata">

### Author: ![Hendrice](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/h/e274bd/32.png) [@Hendrice](https://discourse.paraview.org/u/Hendrice)
#### Post date: [July 21, 2023, 7:59am UTC](https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551/6 "2023-07-21T07:59:25Z")

</div>

Thanks pointing in the right direction so quickly. This indeed did the trick. However the lines at some places seem to be extended beyond the actual line segment in the geometry?  
Default: linewidth=1

 ![lines_default_1.PNG](https://discourse.paraview.org/uploads/default/original/2X/1/1e25342d3b229d2c5fd51c92ae199759c8b79085.jpeg)

linewidth=0.1

 ![lines_0.1.PNG](https://discourse.paraview.org/uploads/default/original/2X/e/e2125ca4c9c373896be06a8fb3b498e4a2893e73.jpeg)

linewidth=0.01

 ![lines_0.01.PNG](https://discourse.paraview.org/uploads/default/original/2X/0/0d9539998cc422fec9fe28873caaadd717fc6e9b.jpeg)

linewidth=1e-6

 ![lines_1e-6.PNG](https://discourse.paraview.org/uploads/default/original/2X/a/af2fafdfbb68396e9834fee51a459f2a5abbb8bd.jpeg)

---

<div class="post-metadata">

### Author: ![Sankhesh\_Jhaveri](https://discourse.paraview.org/user_avatar/discourse.paraview.org/sankhesh_jhaveri/32/3374_2.png) [@Sankhesh\_Jhaveri](https://discourse.paraview.org/u/Sankhesh_Jhaveri)
#### Post date: [July 21, 2023, 10:56am UTC](https://discourse.paraview.org/t/visual-artifacts-at-open-surface-ends-when-raytracing-data-in-vtu-format/12551/7 "2023-07-21T10:56:19Z")

</div>

In that case, you might get a closer result by changing the scaling mode to `ALL_EXACT`.