# Node ordering and volume computation

**URL:** https://discourse.paraview.org/t/node-ordering-and-volume-computation/10826
**Category:** ParaView Support
**Created:** [November 21, 2022, 5:52pm UTC](https://discourse.paraview.org/t/node-ordering-and-volume-computation/10826 "2022-11-21T17:52:59Z")
**Posts on this page:** 1
**Showing post:** 1

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### Author: ![philippeVerney](https://discourse.paraview.org/user_avatar/discourse.paraview.org/philippeverney/32/5670_2.png) [@philippeVerney](https://discourse.paraview.org/u/philippeVerney)
#### Post date: [November 21, 2022, 5:52pm UTC](https://discourse.paraview.org/t/node-ordering-and-volume-computation/10826/1 "2022-11-21T17:52:59Z")

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Hi all,

I have created a small unstructured grid with a tetrahedron (in red) and a wedge (in blue).

 ![image](https://discourse.paraview.org/uploads/default/original/2X/8/8d6a240286ed6c5b7d871679dd6bd8b5f564aa2d.png)

The node ordering for the tetrahedron is : 2 1 0 3  
The node ordering for the wedge is : 0 1 2 4 5 6  
I think this is the correct ordering looking at [https://kitware.github.io/vtk-examples/site/VTKBook/05Chapter5/#Figure%205-2](https://kitware.github.io/vtk-examples/site/VTKBook/05Chapter5/#Figure%205-2)

However when I apply a “cell size” filter on it, I have a (nice) positive value for the tetrahedron but a (bad) negative volume for the wedge. See color bar in above screenshot

I cannot understand what I am missing. Could you help me please?

Remarks :

- If I modify the node ordering of the wedge to 2, 0, 1, 6, 4, 5 its volume is correctly computed.
- If I modify the node ordering of the wedge to 2, 1, 0, 6, 5, 4 its volume is correctly computed.

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