# Odd Behavior when using OSPRay Pathtracer

**URL:** https://discourse.paraview.org/t/odd-behavior-when-using-ospray-pathtracer/13249
**Category:** ParaView Support
**Created:** [November 13, 2023, 10:39pm UTC](https://discourse.paraview.org/t/odd-behavior-when-using-ospray-pathtracer/13249 "2023-11-13T22:39:34Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![bwilfong3](https://discourse.paraview.org/letter_avatar_proxy/v4/letter/b/ecd19e/32.png) [@bwilfong3](https://discourse.paraview.org/u/bwilfong3)
#### Post date: [November 13, 2023, 10:39pm UTC](https://discourse.paraview.org/t/odd-behavior-when-using-ospray-pathtracer/13249/1 "2023-11-13T22:39:34Z")

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Hi all,

I am using Paraview 5.11.0 on a Linux machine via a remote connection to a supercomputer to create some renders of large data sets using Paraview’s ray tracing features. I’m running into a problem where I go from seeing this

 ![Screenshot_2023-11-13_17-34-41](https://discourse.paraview.org/uploads/default/original/2X/9/98f18dce98cf1f1238e493ee0cf690cd8a93dc28.jpeg)  
to seeing this after enabling OSPRay pathtracer with 10 samples per pixel  
 ![Screenshot_2023-11-13_17-35-35](https://discourse.paraview.org/uploads/default/original/2X/3/308a617124b99e0a55872bb856cffede735050fb.jpeg)  
If I exclude the isovolume from the render view, I get an even odder result with a bunch of red lines in a ball shape  
 ![Screenshot_2023-11-13_17-37-06](https://discourse.paraview.org/uploads/default/original/2X/e/e4b7222b8f85c202ba11fa9f53101cfee2f4d265.jpeg)  
Removing both the clip and the isovolume from the render view gives the expected result. Any thoughts on why this may be happening and/or fixes for it? Thanks!

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### 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: [November 17, 2023, 3:43am UTC](https://discourse.paraview.org/t/odd-behavior-when-using-ospray-pathtracer/13249/2 "2023-11-17T03:43:35Z")

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@Dave_DeMarle?

Does this happen with a non-remote setup? If possible, can you test with the 5.12.0-RC1 release as well?

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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: [November 28, 2023, 1:21am UTC](https://discourse.paraview.org/t/odd-behavior-when-using-ospray-pathtracer/13249/3 "2023-11-28T01:21:20Z")

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The ball of red lines is most likely the Client/Server widget state bug that @Sankhesh_Jhaveri re-fixed recently and should work in 5.12 since VTK’s CI covers it.

The remote is running MPI correct? If so, then see [this discussion](https://discourse.paraview.org/t/paraview-doesnt-perform-ray-tracing-ospray-correctly-with-mpi/11529) for the most likely cause. Although from the appearance it might be related to the [pathtracer background regression](https://gitlab.kitware.com/vtk/vtk/-/merge_requests/8577) that was recently fixed and should appear in 5.12.