# Numerics of "Gradient Of Unstructured DataSet" Filter

**URL:** https://discourse.paraview.org/t/numerics-of-gradient-of-unstructured-dataset-filter/638
**Category:** ParaView Support
**Created:** [September 26, 2018, 12:54pm UTC](https://discourse.paraview.org/t/numerics-of-gradient-of-unstructured-dataset-filter/638 "2018-09-26T12:54:58Z")
**Posts on this page:** 1
**Showing post:** 9

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### Author: ![JMuskat](https://discourse.paraview.org/user_avatar/discourse.paraview.org/jmuskat/32/348_2.png) [@JMuskat](https://discourse.paraview.org/u/JMuskat)
#### Post date: [September 27, 2018, 12:08pm UTC](https://discourse.paraview.org/t/numerics-of-gradient-of-unstructured-dataset-filter/638/9 "2018-09-27T12:08:49Z")

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I’ve been working on getting the structured grid and applying the `Gradient` filter once my `Resample To Image` is generated. However, I’m having issues getting `Gradient` to work. When I import my CFD results, I have:

- Point Data: contains point 3D space orientation, velocity vector, velocity-component array(s) [x, y, z]
- Cell Data: Block Number, Cell ID, Cell Type (Tetrahedron)

I can create the structured grid, and the vectors/scalars are transferred over well. I’m able to visualize nicely with the “Volume” rendering. I use `Transform` to scale the data back to the correct scale (m → mm) before creating the structured grid. I am able to apply `Gradient` to either version of the structured grid, but I’m having errors.

For the case where I’ve transformed \> grid generation, I get:

> No Scalar Field has been specified - assuming 1 component!

Which is strange, because I am feeding it a scalar. When applying to the NON-transformed grid, I don’t receive any errors. However, the bounds of the gradient-dataset are stretched/do not stay at the same location or scale. The top two images show the structured grid/shape of my volume render. The bottom two show how `Gradient` caused a massive expansion.

 ![Volume_structured](https://discourse.paraview.org/uploads/default/original/1X/19c35c8325dd672545afc59387fac59ac47f7dea.png)

 ![Volume_gradientExploded](https://discourse.paraview.org/uploads/default/original/1X/4ce2a40cdba5e3c39b5b4991cef5fefc075f1d47.png)

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