# OSPray pathtracer: erratic walls
**URL:** https://discourse.paraview.org/t/ospray-pathtracer-erratic-walls/7966
**Category:** ParaView Support
**Created:** [September 9, 2021, 4:41pm UTC](https://discourse.paraview.org/t/ospray-pathtracer-erratic-walls/7966 "2021-09-09T16:41:42Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@bastian](https://discourse.paraview.org/u/bastian)
#### Post date: [September 9, 2021, 4:41pm UTC](https://discourse.paraview.org/t/ospray-pathtracer-erratic-walls/7966/1 "2021-09-09T16:41:42Z")
When batch-rendering transient data for video production using the OSPray pathtracer I frequently observe **erroneous walls popping up**.
These are most often (but not always) aligned with the xy, the yz, or the xz-plane and would then have the only one visible corner at the origin. They appear pitch black or partially translucent.
Is there any knowledge, what I can do to avoid this issue?
**Background:**
_I am batch-rendering data-heavy transient scenes. In order to reduce the time spent reading data my state files usually have multiple layouts each holding a render view. These render views visualize the same data in different ways._
_My paraview sessions then iterates through the time steps, and for each time step iterates through the render views, producing a png file for each view per time step._
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [September 10, 2021, 9:17am UTC](https://discourse.paraview.org/t/ospray-pathtracer-erratic-walls/7966/2 "2021-09-10T09:17:21Z")
FYI @Francois_Mazen @timothee.chabat
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### Author:  [@Dave\_DeMarle](https://discourse.paraview.org/u/Dave_DeMarle)
#### Post date: [September 10, 2021, 5:00pm UTC](https://discourse.paraview.org/t/ospray-pathtracer-erratic-walls/7966/3 "2021-09-10T17:00:38Z")
Can you share a picture with the erroneous walls in it? I’m hoping it will help us to identify the specific problematic code path. Thanks.
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### Author:  [@bastian](https://discourse.paraview.org/u/bastian)
#### Post date: [October 5, 2021, 4:48pm UTC](https://discourse.paraview.org/t/ospray-pathtracer-erratic-walls/7966/4 "2021-10-05T16:48:33Z")
I was a bit fast at deleting the unwanted images, but here is one example:
I think that one corner is always at the origin (0,0,0).
This looks like the same issue to me:
> [@background error in raytracing](https://discourse.paraview.org/t/background-error-in-raytracing/7898):
>
> With paraview 5.9.1, I have a problem where the bundled ospray. Rendered images contain random errors where a large region of grey color may appear in the saved snapshot image. One such image is attached as an example. I was using ospray path tracer and backplate. Normal images have clear white background, but in a long sequence of rendering, some images may randomly contain these grey errors. Some cases the grey area is large as the attached image, sometimes the grey area i…
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### Author:  [@timothee.chabat](https://discourse.paraview.org/u/timothee.chabat)
#### Post date: [October 8, 2021, 11:44am UTC](https://discourse.paraview.org/t/ospray-pathtracer-erratic-walls/7966/5 "2021-10-08T11:44:57Z")
I also think this is the same issue. I couldn’t looked into it so far but I’ll keep you updated if I discover something along the way!