# OpitX pathtracer : Is 4 samples per pixel possible?
**URL:** https://discourse.paraview.org/t/opitx-pathtracer-is-4-samples-per-pixel-possible/8265
**Category:** ParaView Support
**Created:** [October 27, 2021, 3:45am UTC](https://discourse.paraview.org/t/opitx-pathtracer-is-4-samples-per-pixel-possible/8265 "2021-10-27T03:45:42Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@Gwang-Jin\_Lee](https://discourse.paraview.org/u/Gwang-Jin_Lee)
#### Post date: [October 27, 2021, 3:45am UTC](https://discourse.paraview.org/t/opitx-pathtracer-is-4-samples-per-pixel-possible/8265/1 "2021-10-27T03:45:42Z")
Hello,
I am using OptiX pathtracer in ParaView 5.9 version. When I use 3 samples per pixel, I obtained low quality.
So I need 4 Samples per Pixel. But paraview aborted when I used 4 samples per pixel with the error message:
> terminate called after throwing an instance of ‘optix::Exception’
> what(): Already mapped (Details: Function “RTresult bufferMap(RTbuffer, unsigned int, unsigned int, void\*, void\*\*)” caught exception: Buffer is already mapped)
I am using TITAN RTX graphic driver. OptiX worked well up to 3 samples per pixel. But I don’t know why 4 samples per pixel occured the error.
Thank you.
Best regards,
Gwang-Jin
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [October 27, 2021, 6:20am UTC](https://discourse.paraview.org/t/opitx-pathtracer-is-4-samples-per-pixel-possible/8265/2 "2021-10-27T06:20:49Z")
> =4 sample per pixel trigger the denoising of the image, which cannot be deactivated with OptiX afaik.
Looks like an optix bug or optix integration bug.
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### Author:  [@timothee.chabat](https://discourse.paraview.org/u/timothee.chabat)
#### Post date: [October 27, 2021, 7:08am UTC](https://discourse.paraview.org/t/opitx-pathtracer-is-4-samples-per-pixel-possible/8265/3 "2021-10-27T07:08:50Z")
This is a known bug of PV 5.9 bug where OptiX + denoiser makes ParaView crash. The workaround is to enable OSPRay, use 4 SPP, disable denoiser, then switch back to OptiX with the denoiser disabled.
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### Author:  [@timothee.chabat](https://discourse.paraview.org/u/timothee.chabat)
#### Post date: [October 27, 2021, 7:11am UTC](https://discourse.paraview.org/t/opitx-pathtracer-is-4-samples-per-pixel-possible/8265/4 "2021-10-27T07:11:55Z")
I forgot to mention but this bug has been fixed in Paraview 5.10 (coming soon) 🙂
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### Author:  [@Gwang-Jin\_Lee](https://discourse.paraview.org/u/Gwang-Jin_Lee)
#### Post date: [October 27, 2021, 8:19am UTC](https://discourse.paraview.org/t/opitx-pathtracer-is-4-samples-per-pixel-possible/8265/5 "2021-10-27T08:19:12Z")
Thank you for your comment. The workaround worked well. But I found that I need 4 SPP with the denoiser enabled. Will Paraview 5.10 support 4 SPP with the denoiser enabled? Thank you.
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### Author:  [@timothee.chabat](https://discourse.paraview.org/u/timothee.chabat)
#### Post date: [October 27, 2021, 8:23am UTC](https://discourse.paraview.org/t/opitx-pathtracer-is-4-samples-per-pixel-possible/8265/6 "2021-10-27T08:23:36Z")
Yes it will, you can already test the first release candidate of ParaView 5.10 following this link. The second release candidate should come in the following days and will be more stable than RC1.
[https://www.paraview.org/download/](https://www.paraview.org/download/)