NVIDIA IndeX for files based on Pyevtk

Hello guys,

I use the python library “pyevtk” to export numpy arrays to a “.vtr” file (function gridToVTK).
But I don’t see the Nvidia IndeX option within the representation option of ParaView when the plugin is loaded. I have already tested the plugin with a wavelet object, which worked fine. In addition, I have tested a “.vtu” export via pyevtk (function pointsToVTK) as well, which gives me the option but does not give me any result. Does anyone already have experience with this combination?

Welcome to the ParaView community, @dynentropy.

“.vtr” files contain rectilinear grids, which are regular grids with potentially non-uniform spacing between successive planes in the three dimensions. Starting in ParaView 5.9, due out in a couple months, ParaView’s built-in volume renderer will be able to render regular grids. The IndeX plug-in, however, apparently does not.

You could run the Resample to Image filter on your “.vtr” file to produce a uniform grid, then IndeX volume rendering should be available. That is likely the most efficient way to proceed, especially if your “.vtk” inter-plane spacing is uniform in all three dimensions. Otherwise, you can run the Tetrahedralize filter to turn your rectlinear grid into an unstructured grid and volume render that. However, that will increase the memory needed tremendously, so it’s not the best option.

Hope that helps.

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Hello Cory,

thank you very much - That helped!! The first approach ( Resample to Image) works fine!
Thanks for the information! I’m looking forward to ParaView 5.9.

So, .vtr files are the simplest and least memory depending files? It is a pity that these are not considered. Especially through the speed gain due to Nvidia IndeX.

Strictly, speaking, “.vti” files are slightly smaller because one number is used to represent the spacing between planes, whereas “.vtr” store three arrays for the inter-plane spacing, one for each dimension. I don’t know what the IndeX team’s plans are for supporting rectilinear grids in volume rendering, I can only speak to what is supported in ParaView’s built-in volume renderer.

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