Can we flip left handed normals to right handed normals?

ParaView Support
1

From a user:

I have a grid model in the netcdf format. It has Nx x Ny x Nz gridpoints with a given grid spacing. At each node, there is one variable, i.e. rho(density). The model is input as a left-hand rule model. I would like to see how the model looks if it was a RH rule model. Essentially, that would entail having the X nodes have a reverse of their ranking, xmax becomes xmin, xmin becomes xmax. Is there any switch in Paraview that would do that automatically, or do I need to recreate my model.

Hopefully, my description is sufficient to explain what I would like to do.

2

Would it work to run the Transform filter and set Scale to (-1, 1, 1)?

3

I was thinking the same thing, but a little trepidatious about the effect that would have on surface normals, volumes, etc. caused by inverting the elements.

4

You’re right. It does add some weirdness. For example, if I do this scale on a 3D image and then Contour it, the normals come out all wrong. However, converting the data to an unstructured grid with Clean to Grid at any point seems to resolve the problems. So buyer beware.

I guess to be safe you would have to reorder all of the points. I don’t know of any existing filter to do that.

5

Would it be worth while (long term) creating a filter that would do this?

6

How often would people need it? Usually this type of thing is taken care of in the reader.

7

There is the Reflect filter which takes care of normals, cell inversions and other items like that. I think it only works for unstructured grids and polydata though.