# Does paraview support quadratic cgns files and visualize high order mesh and solutions?
**URL:** https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146
**Category:** ParaView Support
**Created:** [December 29, 2020, 5:14pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146 "2020-12-29T17:14:38Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@daxian](https://discourse.paraview.org/u/daxian)
#### Post date: [December 29, 2020, 5:14pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/1 "2020-12-29T17:14:38Z")
Hello,
I read in a quadratic cgns file with solutions without any problems. However, it appears paraview only extracted the linear mesh and data. Do I need a special filter to visualize native cgns files in high order mode?
Thanks
Dave
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [January 4, 2021, 9:23am UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/2 "2021-01-04T09:23:51Z")
I’m not a CGNS expert, but the reader may have limited support. Could you share a file ?
---
### Author:  [@daxian](https://discourse.paraview.org/u/daxian)
#### Post date: [January 8, 2021, 6:33pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/3 "2021-01-08T18:33:43Z")
Yes. I am sharing one degree 2 file, which contains quadratic elements and solutions of hex elements:
> **[merged\_p2\_hex.cgns](https://www.dropbox.com/s/la6uswo3590gx4d/merged_p2_hex.cgns?dl=0)**
>
> Shared with Dropbox
I could see p2 surfaces but not p2 iso-surfaces.
Thanks for your help!
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [January 12, 2021, 12:57pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/4 "2021-01-12T12:57:33Z")
Tri-Quadratic-Hexahedron cells seems to be read correctly. What are you looking for ?
---
### Author:  [@daxian](https://discourse.paraview.org/u/daxian)
#### Post date: [January 12, 2021, 5:44pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/5 "2021-01-12T17:44:39Z")
When I do contour (or iso-surfaces), it appears to be still only linear, not high-order. When I change the non-linear refinement to 2, 3, 4, nothing happens.
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [January 13, 2021, 10:47am UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/6 "2021-01-13T10:47:25Z")
Looks like the contour filter does not support generating iso surface from these kind of cells. Use tetrahedralize first ?
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### Author:  [@daxian](https://discourse.paraview.org/u/daxian)
#### Post date: [January 13, 2021, 2:59pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/7 "2021-01-13T14:59:24Z")
I will try tets, and let you know. Do you plan to support high-order iso-surfaces for hexahedral, prismatic and pyramidal elements? I have a mixed-mesh file, which hang during the importing phase. I will try to clear that file for release and put it here.
---
### Author:  [@daxian](https://discourse.paraview.org/u/daxian)
#### Post date: [January 15, 2021, 6:23am UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/8 "2021-01-15T06:23:38Z")
Paraview may have a bug in reading mixed quadratic cgns file. The latest version (5.9) crashed when reading the following file:
> **[mixed\_mesh\_sol.cgns](https://www.dropbox.com/s/88ghvmlvhktph25/mixed_mesh_sol.cgns?dl=0)**
>
> Shared with Dropbox
---
### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [January 15, 2021, 8:07am UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/9 "2021-01-15T08:07:32Z")
I reproduce:
```
( 24.307s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(145) is not a 3D cell.
( 24.311s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(48) is not a 3D cell.
( 24.311s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(160) is not a 3D cell.
( 24.312s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(176) is not a 3D cell.
( 24.313s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(97) is not a 3D cell.
( 24.313s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(160) is not a 3D cell.
( 24.313s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(20) is not a 3D cell.
( 24.314s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(48) is not a 3D cell.
( 24.314s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(48) is not a 3D cell.
( 24.314s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(203) is not a 3D cell.
( 24.314s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(112) is not a 3D cell.
( 24.314s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(240) is not a 3D cell.
( 24.315s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(48) is not a 3D cell.
( 24.315s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(155) is not a 3D cell.
( 24.315s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(144) is not a 3D cell.
( 24.315s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(112) is not a 3D cell.
( 24.316s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type vtkHigherOrderTetrahedron(64) is not a 3D cell.
( 24.316s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(49) is not a 3D cell.
( 24.316s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type vtkHigherOrderHexahedron(67) is not a 3D cell.
( 24.316s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(105) is not a 3D cell.
( 24.317s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(85) is not a 3D cell.
( 24.317s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(114) is not a 3D cell.
( 24.317s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(117) is not a 3D cell.
( 24.317s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(104) is not a 3D cell.
( 24.318s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(110) is not a 3D cell.
( 24.318s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(116) is not a 3D cell.
( 24.318s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(116) is not a 3D cell.
( 24.318s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(203) is not a 3D cell.
( 24.319s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(152) is not a 3D cell.
( 24.319s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type vtkParametricTetraRegion(55) is not a 3D cell.
( 24.319s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(182) is not a 3D cell.
( 24.320s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(84) is not a 3D cell.
( 24.320s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(203) is not a 3D cell.
( 24.320s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(207) is not a 3D cell.
( 24.320s) [paraview]vtkUnstructuredGridGeom:1204 ERR| vtkUnstructuredGridGeometryFilter (0x1a2f1fd0): Cell type UnknownClass(86) is not a 3D cell.
```
FYI @MicK7
---
### Author:  [@MicK7](https://discourse.paraview.org/u/MicK7)
#### Post date: [January 15, 2021, 12:54pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/10 "2021-01-15T12:54:06Z")
The CGNS reader has limited support for High Order. However, it reads perfectly well cgns public files for the NASA CRM configuration ([https://acdl.mit.edu/HOW5/CR1\_CommonResearchModel/pointwise\_HOW5/cgns/](https://acdl.mit.edu/HOW5/CR1_CommonResearchModel/pointwise_HOW5/cgns/)).
I suspect that the order of the connectivities written in mixed\_mesh\_sol.cgns is wrong.
---
### Author:  [@daxian](https://discourse.paraview.org/u/daxian)
#### Post date: [January 15, 2021, 3:16pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/11 "2021-01-15T15:16:05Z")
Paraview has no problems reading large linear mixed meshes. This mesh is a small quadratic mixed mesh including all element types. I suspect a bug in reading such a mesh. Hopefully the small size of the file can help you debug.
---
### Author:  [@daxian](https://discourse.paraview.org/u/daxian)
#### Post date: [January 15, 2021, 4:13pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/12 "2021-01-15T16:13:34Z")
I identified a potential element range mistake. I will update soon.
---
### Author:  [@daxian](https://discourse.paraview.org/u/daxian)
#### Post date: [January 15, 2021, 6:54pm UTC](https://discourse.paraview.org/t/does-paraview-support-quadratic-cgns-files-and-visualize-high-order-mesh-and-solutions/6146/13 "2021-01-15T18:54:21Z")
There was indeed an error in the element range. After I fixed this error, the file could be read correctly. However, there may still be a minor bug. I saw some internal faces being displayed when I set the opacity to less than 1. Here is the file:
[https://www.dropbox.com/s/onqi3maq4vach25/BoxHybridQ2.cgns.gz?dl=0](https://www.dropbox.com/s/onqi3maq4vach25/BoxHybridQ2.cgns.gz?dl=0)