simtk.org

I am a student attempting to extract the NURBS surface data from SimVascular models, in order to conduct Isogeometric Analysis on bloodflow, eventually looking to model arterial stents.
Having found https://www.vascularmodel.com/ and the models contained within this repository, I have found them ideal for my project, however, due to my lack of technical understanding, I have so far been unable to extract the NURBS data (specifically, knot vectors, control points and weights).

I have tried:
- Converting the models to STEP/IGES formats directly
- Importing the models into CAD software
- Reading data directly from .vtk files
- Using the SV python installation
- Going through the source code to try and understand in what format and which files the nurbs data is being extracted to.
- Searching through this forum

None of these approaches have yielded anything substantial for me, and I am worried that I will not be able to complete my project in time for my academic deadlines if I keep attempting a wide varity of approaches as listed above. I am incredibly grateful to anyone that has taken the time to read this and could provide some sort of guidance on what technical approach I should prioritise.

Thank you,
Hugo

Hello Hugo,

The models in the repository are polygonal surfaces represented using VTK data structures.

You will need to first convert the SV VTK VTP model file into STL format; you can do this using a VTK Python script. You can then read in the STL format into a CAD program that supports tessellating polygonal surfaces into NURBS patches.

Cheers,
Dave

Hi David,

Thank you for replying so quickly and concisely.
I see now that I was working with the incorrect assumption that the SV models were in a NURBS format, and I needed to find a way to extract this data, as a result, I did not want to 'refit' NURBS from VTK data, 'losing' information.

Thank you once again for the clarification and guidance,
Hugo