I have a problem with the command “vmtkparticletracer”. Putting as input the files (-ifile merge.vtu -sfile source.vtp) I obtain an empty output (traces.vtp). The command line is “vmtkparticletracer -ifile merge.vtu -sfile source.vtp -maximumnumberofsteps 100000 -minspeed 10 -ofile traces.vtp”. It does not provide an error message, but the streamlines in the traces file are not created even if the inputs are correct.
Can you help me?
Thank you in advance!

It hard to tell what can go wrong. Maybe if you share your input data set (upload somewhere and post the link here) then somebody can have a look at it.

The files are available here: