# Volume Ray Casting Isosurface on CPU

**URL:** https://discourse.vtk.org/t/volume-ray-casting-isosurface-on-cpu/5294
**Category:** Support
**Created:** [March 2, 2021, 4:12am UTC](https://discourse.vtk.org/t/volume-ray-casting-isosurface-on-cpu/5294 "2021-03-02T04:12:20Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![paulojamorim](https://discourse.vtk.org/user_avatar/discourse.vtk.org/paulojamorim/32/2351_2.png) [@paulojamorim](https://discourse.vtk.org/u/paulojamorim)
#### Post date: [March 2, 2021, 4:12am UTC](https://discourse.vtk.org/t/volume-ray-casting-isosurface-on-cpu/5294/1 "2021-03-02T04:12:20Z")

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Hi Everyone,

Is there any way to use volume ray casting isosurface on CPU? Like old vtkVolumeRayCastIsosurfaceFunction.

Best regards,  
Paulo Amorim

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### Author: ![lassoan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/lassoan/32/50_2.png) [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [March 2, 2021, 10:46pm UTC](https://discourse.vtk.org/t/volume-ray-casting-isosurface-on-cpu/5294/2 "2021-03-02T22:46:37Z")

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You can use vtkFixedPointVolumeRayCastMapper with a composite function that mimics an isosurface function (scalar opacity transfer function contains a single large step).