# Inconsistent rendering of point data in hexahedrall cells

**URL:** https://discourse.paraview.org/t/inconsistent-rendering-of-point-data-in-hexahedrall-cells/6536
**Category:** ParaView Support
**Created:** [February 23, 2021, 4:57pm UTC](https://discourse.paraview.org/t/inconsistent-rendering-of-point-data-in-hexahedrall-cells/6536 "2021-02-23T16:57:24Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![bvlqz](https://discourse.paraview.org/user_avatar/discourse.paraview.org/bvlqz/32/5971_2.png) [@bvlqz](https://discourse.paraview.org/u/bvlqz)
#### Post date: [February 23, 2021, 4:57pm UTC](https://discourse.paraview.org/t/inconsistent-rendering-of-point-data-in-hexahedrall-cells/6536/1 "2021-02-23T16:57:24Z")

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Hi,

When I load a vtkUnstrucuredGrid and color by scalars, I was expecting the coloring to be symetrical, but it looks like there is an interpolation error:

 ![image](https://discourse.paraview.org/uploads/default/original/2X/a/a7debaa86d0df56cfeca0e58f91d96311d048c2d.png)  
 ![image](https://discourse.paraview.org/uploads/default/original/2X/f/f650ad9f5835dd64aa0888b7343129e171e250fb.png)

here’s my data:

```
# vtk DataFile Version 4.2
vtk output
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 16 float
0	0	0
0.1	0	0
0.1	0.1	0
0	0.1	0
0	0	0.1
0.1	0	0.1
0.1	0.1	0.1
0	0.1	0.1

0.2	0	0
0.3	0	0
0.3	0.1	0
0.2	0.1	0
0.2	0	0.1
0.3	0	0.1
0.3	0.1	0.1
0.2	0.1	0.1

CELLS 2 18
8 0 1 2 3 4 5 6 7
8 8 9 10 11 12 13 14 15

CELL_TYPES 2
12
12

POINT_DATA 16
SCALARS active_set int 1
LOOKUP_TABLE default
0 1 1 0
0 0 0 0
1 0 0 1
0 0 0 0

```

I’m using ParaView 5.9.0 on Windows 10

Thank you!  
- Jorge

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### Author: ![Kenneth\_Moreland](https://discourse.paraview.org/user_avatar/discourse.paraview.org/kenneth_moreland/32/15033_2.png) [@Kenneth\_Moreland](https://discourse.paraview.org/u/Kenneth_Moreland)
#### Post date: [February 23, 2021, 6:45pm UTC](https://discourse.paraview.org/t/inconsistent-rendering-of-point-data-in-hexahedrall-cells/6536/2 "2021-02-23T18:45:42Z")

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This is a known issue that is discussed at length here: [Unsymmetric contour rendered by symmetric data](https://discourse.paraview.org/t/unsymmetric-contour-rendered-by-symmetric-data/4118/13).

The issue is that as an optimization step, rendering systems will divide primitives into triangles, and that causes the interpolation to change from non-simplexes. Normally the difference is minor, but when you have large cells with dramatically changing data, as is your case, then the difference is much greater.

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<div class="post-metadata">

### Author: ![bvlqz](https://discourse.paraview.org/user_avatar/discourse.paraview.org/bvlqz/32/5971_2.png) [@bvlqz](https://discourse.paraview.org/u/bvlqz)
#### Post date: [February 24, 2021, 3:40pm UTC](https://discourse.paraview.org/t/inconsistent-rendering-of-point-data-in-hexahedrall-cells/6536/3 "2021-02-24T15:40:58Z")

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Oh, I see  
Thank you for your answer! @Kenneth_Moreland