Fail in meshing surface

[Sara BENCHARA]

Hello,

For my thesis, I am working on pulmonary hypertension and would like to use your software for my simulations. To do so, I work on segmented models on a GE (general electric) console exported in STL format. For simple geometries such as a syringe, I do not encounter any problems. But when importing geometries of pulmonary arteries, I am confronted with a mesh error which does not allow me to go further in my simulations. However, what I find surprising is that for some models a volume mesh is possible but not a surface mesh.
Would you have solutions to bring me in front of this problem ?
If needed, I can send you my STL file.

Sincerely,

Sara

[David Parker]

Hi Sara,

STL models typically have poor triangulations (e.g. long thin triangles) and small features, and are therefore difficult to mesh. You will need to experiment with Remesh Size in the SV Modeling Tool to get a decent model surface.

Upload you STL someplace I can download it and I'll have a look.

Cheers,
Dave

[Sara BENCHARA]

Hello,

Forgive me for my late reply.
I have tried your proposals for the mesh but I do not get more results.
I am attaching geometries that I have tested on Simvascular which gives volumetric meshes but not surface meshes.
The 3DModel and 3DmodelcutMLsmooth files seem to be too irregular to make a mesh (even though the volumetric one works).
The 2 other files seem smoother to me.
For cut geometries, I close them on simvascular using the tool "Files Holes w. IDs"

I thank you in advance.

https://www.icloud.com/iclouddrive/03bq ... imvascular


Sincerly,

Sara

[David Parker]

Hi Sara,

I looked at your models. None of the larger models are suitable for SV. The smaller (DC_GE_ET_cutML2.smooth.stl) model also has problems, near-zero area triangles along the vessel boundaries (shown in red)

Screen Shot 2022-07-20 at 12.36.44 PM.png (453.62 KiB) Viewed 1269 times

and zoomed in

Screen Shot 2022-07-20 at 12.32.57 PM.png (20.72 KiB) Viewed 1269 times

Models need to be smooth with no small features (e.g. areas where triangles are raised above the surrounding surface) and well-defined boundaries at vessel ends. The surface triangles should have good aspect ratio and be about the same size.

Cheers,
Dave

[Antoine Marchi]

Hello

I'm also working on modeling the pulmonary arteries with Sara using SimVascular, by directly importing an STL file, and I'm unable to generate a mesh (the message 'fail of meshing' appears). However visually the structure seems smooth (I've tested several 3D processing software including Meshmixer, in vain).
Do you have any suggestions for debugging this meshing step ?
Attached is my test file:
https://drive.google.com/drive/folders/ ... drive_link

Thanks in advance for your help

Sincerly,

Antoine

[David Parker]

Hi Antoine,

Looking at the TestMM model I see a problem with face 3, a poor triangulation, probably a non-manifold surface.

Screen Shot 2024-03-20 at 2.05.50 PM.png (138.23 KiB) Viewed 1129 times

A surface needs to be well-defined for it to mesh.

The TestOf model appears to have non-triangular polygons.

Cheers,
Dave

[Antoine Marchi]

Hi David

I finally managed to generate several meshes with Simvascular. To achieve this, I used the software 3Dslicer, which allows remeshing (STL file) using an algorithm ACDV "Advective Convective Discretization Vortex," which seems more suitable than those used in general-purpose 3D modeling software. Then, I import the obtained .STL file into Simvascular, and it works.

Thank you once again for your guidance and support.

Best regards,

Antoine

[David Parker]

Hi Antoine,

Thanks for sharing what you did using 3Dslicer, I'm sure other users will find it helpful.

I hope to some day improve SV meshing when I can find the time.

Cheers,
Dave

[Melton Parham]

Hi Antoine,

I am also having troubles with importing STL created from a segmentation in 3D slicer into SimVascular.
What is the Advective Convective Discretization Vortex (ACD)? I cannot find that in any documentation for 3D slicer?

Thank you,
Melton

[Antoine Marchi]

Hi Melton

Sorry for my late response.
What kind of troubles do you have ?
Slicer allows you to generate a Tetgen mesh of your model, which is one of the mesh types used by Simvascular.
I also use Blender to check and sometime repair the mesh before load it into Simvascular.

"Approximated Centroidal Voronai Diagrams" ACDV description :
https://www.creatis.insa-lyon.fr/~valet ... ject/acvd/

Regards

Antoine