Invisible volumes when using "Warp by vector" filter

Hi!

I’m using

  • Paraview 5.8.0
  • Windows 10, 64-bits, x64 system

What I want to do:
I want to display a scalar field over the cells of a structured grid, by using the volume representation (so I may use the Multi Components Mapping) and at the same time show the displacements of the nodes (by using the Warp by vector filter).

What happens:
I use the following VTK-file as data input:

# vtk DataFile Version 3.0
vtk output
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 3 3 1
SPACING 1 1 1
ORIGIN 0 0 0
CELL_DATA 4
SCALARS scalars float 2
LOOKUP_TABLE default
0 0
0.4 0
0.4 1
0 1

POINT_DATA 9
VECTORS vect3 float
-1 -1 0 
-1 -1 0 
-1 -1 0 
-1 0 0 
-1 0 0 
-1 0 0 
-1 1 0 
-1 1 0
-1 1 0

then, when importing to Paraview, I use the Warp by vector filter on vect3 and then display scalars with a volume representation.
The problem is that the volume is now invisible, and it doesn’t matter if I check the Multi components mapping checkbox or not.

Am I doing something wrong maybe? I have tried to simplify the example as much as possible, and hope it should be obvious what I want to achieve.

EDIT: Here’s a picture of how it looks like when the volumes are invisible

You data is 2D. VolumeRendering of 2D data is not supported.
What kind of visualization are you expecting when volume rendering 2D data ?

Woops, I didn’t even reflect over that fact, thank you for pointing that out!

The reason I want to use volume rendering is as I mentioned before: I want to use Multi Component Mapping on my two component scalar field. And this would include visualising 2D geometries this way.

If I extend the data to 3D, 1 element thick in the z-dimension, it works fine :slight_smile:

However, I encounter another small issue this time. Using this file:

# vtk DataFile Version 3.0
vtk output
ASCII
DATASET STRUCTURED_POINTS
DIMENSIONS 3 3 2
SPACING 1 1 1
ORIGIN 0 0 0

CELL_DATA 4
SCALARS scalars float 2
LOOKUP_TABLE default
0.4 0
0 0
0.4 1
0 1

POINT_DATA 18
VECTORS vect3 float
-1 -1 0 
-1 -1 0 
-1 -1 0 
-1 0 0 
-1 0 0 
-1 0 0 
-1 1 0 
-1 1 0
-1 1 0
-1 -1 0 
-1 -1 0 
-1 -1 0 
-1 0 0 
-1 0 0 
-1 0 0 
-1 1 0 
-1 1 0
-1 1 0

I get this error message when using Multi Component Mapping on the scalar field.

In this video you see the steps I take (the error message box is however not captured in the video):

I guess there is some formatting error in the VTK file that is not breaking, but still not 100% correct. I have however a hard time finding a good VTK reference to guide me. Do you know what could be the problem here?

Small bug in ParaView forcing the coloring by point data, you seems to have figured it out that you need to reselect the cell data array to fix it.

https://gitlab.kitware.com/paraview/paraview/-/issues/19991