# Tesselate filter on polygon indicates no parametrization
**URL:** https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966
**Category:** Development
**Tags:** vtk
**Created:** [February 19, 2024, 6:35pm UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966 "2024-02-19T18:35:00Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@cessenat](https://discourse.paraview.org/u/cessenat)
#### Post date: [February 19, 2024, 6:35pm UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/1 "2024-02-19T18:35:01Z")
The “Tesselate” filter applied on “VTK\_POLYGON” indicates “Input dataset has cells without parametization”. Example file:
```auto
# vtk DataFile Version 3.0
Generated by Hand
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 14 double
0.0 0.0 0.001
0.0 0.0 0.002 1.0 0.0 0.0
1.0 1.0 0.0 0.0 1.0 0.0
2.0 0.0 0.0 2.0 1.0 0.0
0.5 0.1 0.0 1.0 0.6 0.0
0.6 1.1 0.0 0.1 0.4 0.0
2.0 -0.5 0.0 1.0 -1.0 0.0
0.0 -0.6 0.0
CELLS 2 12
4 2 5 6 3
6 1 13 12 11 5 2
CELL_TYPES 2
9
7
POINT_DATA 14
FIELD FieldData 1
TempNode 1 14 float
0.0
0.0 1.5
0.2 0.0
1.0 0.4
2.0 0.5
0.25 0.15
0.25 0.45
0.13
```
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 20, 2024, 9:45am UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/2 "2024-02-20T09:45:03Z")
Use `Triangulate` filter before using `Tesselate`.
---
### Author:  [@cessenat](https://discourse.paraview.org/u/cessenat)
#### Post date: [February 21, 2024, 9:37am UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/3 "2024-02-21T09:37:14Z")
The “Triangulate” filtre is grey’ed (not applicable) on my Ubuntu 22.04 Paraview 5.10.0-RC1.
Example below, even with a simple quad.
```auto
# vtk DataFile Version 3.0
Generated by Hand
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 4 double
1.0 0.0 0.0 2.0 0.0 0.0 2.0 1.0 0.0 1.0 1.0 0.0
CELLS 1 5
4 1 2 3 0
CELL_TYPES 1
9
POINT_DATA 4
FIELD FieldData 1
TempNode 1 4 float
1.5 1.0 2.0 0.5
```
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 21, 2024, 10:05am UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/4 "2024-02-21T10:05:50Z")
Use “ExtractSurface” first if you want to work with surface, or use “Tetrahedralize” instead.
---
### Author:  [@cessenat](https://discourse.paraview.org/u/cessenat)
#### Post date: [February 21, 2024, 11:21am UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/5 "2024-02-21T11:21:30Z")
OK thanks. But it cannot be applied on quadratic elements at the same time.
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 21, 2024, 4:19pm UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/6 "2024-02-21T16:19:26Z")
please share your data.
---
### Author:  [@cessenat](https://discourse.paraview.org/u/cessenat)
#### Post date: [February 21, 2024, 4:56pm UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/7 "2024-02-21T16:56:08Z")
```auto
# vtk DataFile Version 3.0
Generated by Hand
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 21 double
0.0 0.0 0.001
0.0 0.0 0.002 1.0 0.0 0.0
1.0 1.0 0.0 0.0 1.0 0.0
2.0 0.0 0.0 2.0 1.0 0.0
0.5 0.1 0.0 1.0 0.6 0.0
0.6 1.1 0.0 0.1 0.4 0.0
2.0 -0.5 0.0 1.0 -1.0 0.0
0.0 -0.6 0.0 -1.0 0.0 0.0
-0.5 0.5 0.0 -0.5 0.0 0.0
2.5 0.0 0.0 2.3 0.8 0.0
2.4 1.5 0.0 1.9 1.5 0.0
CELLS 5 35
8 1 2 3 4 7 8 9 10
4 2 5 6 3
6 1 13 12 11 5 2
6 4 14 1 15 16 10
6 5 17 18 19 20 6
CELL_TYPES 5
23
9
7
22
7
CELL_DATA 5
SCALARS material int
LOOKUP_TABLE default
1
2 2 2
3
FIELD FieldData 1
TempCell 1 5 float
0.0
0.4 0.1 0.2
0.3
POINT_DATA 21
FIELD FieldData 1
TempNode 1 21 float
0.0
0.0 1.5 0.2 0.0 1.0
0.4 2.0 0.5 0.25 0.15
0.25 0.45 0.13 0.21 0.41
0.17 0.23 0.45 0.06 0.28
```
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [February 21, 2024, 5:00pm UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/8 "2024-02-21T17:00:45Z")
Tetrahedralize + Tesselate works fine on your data:
---
### Author:  [@dcthomp](https://discourse.paraview.org/u/dcthomp)
#### Post date: [February 21, 2024, 5:15pm UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/9 "2024-02-21T17:15:15Z")
Yes, but I think the point is that that Tetrahedralize (or ExtractSurface + Triangulate) do not offer an option for how finely to subdivide higher-order cells, so you are always left with a coarse subdivision for higher-order cells should you need to triangulate polygons.
I don’t know how much work it would take to provide a “non-linear subdivision level” to the Tetrahedralize and Triangulate filters.
---
### Author:  [@cessenat](https://discourse.paraview.org/u/cessenat)
#### Post date: [February 21, 2024, 5:24pm UTC](https://discourse.paraview.org/t/tesselate-filter-on-polygon-indicates-no-parametrization/13966/10 "2024-02-21T17:24:40Z")
That’s the point.
Initially, I thought the Tesselate operator, that works on triangles and quads, could also apply on polygons.