Mesh generation error of a thigh bone geometry

Moderator: GiD Team

Marg_Barros
Posts: 5
Joined: Mon Jun 04, 2018 4:26 pm

Mesh generation error of a thigh bone geometry

Postby Marg_Barros » Tue Jun 05, 2018 3:49 pm

I am a new user of the GiD software, I have access to GiD 10 and some throubles in the mesh generation process are arising but I don't have a clue on how to solve it. So I'll explain what I'm doing and the problem.

I extracted a thigh bone geometry with Invesalius software. In Rhino 6, I've fixed the STL file incompatibilities errors, thus, generating a closed mesh of the thigh bone geometry. I saved the mesh as a STL file and imported it with the GiD 13 (in the lab I work there are other GiD versions available), then I used the command "Geometry >> Create >> Geometry from mesh >> one element-one surface" to generate the geometries I needed, the volume was created using the "Geometry >> Create >> Volume >> By contour" command.

Then, I opened the project file in the GiD 10 to generate the mesh. I assign the tetrahedral element type to the volume and then click on the Mesh generation option, with the "get meshing parameters from model" option checked, then the size of the elements are assigned and the "Ok" button is hit. I've tried this process with different sizes, from 9 to 0.05. The software starts the meshing process and, abruptly, stops near the surface mesh procedure is complete with the same error message: " 28249 Couldn't mesh a this location".

* I've tried to assign the element size as 0.01 but the procedure's memory requirement was beyond my computer's memory affordability.

GiD 10 Error Message.png
The error message it outputs.
GiD 10 Error Message.png (263.21 KiB) Viewed 2205 times
User avatar
escolano
Posts: 1568
Joined: Thu Sep 18, 2014 3:31 pm

Re: Mesh generation error of a thigh bone geometry

Postby escolano » Tue Jun 05, 2018 6:01 pm

The success in generating a volume mesh is very dependent on the quality of the surface mesh.
If your STL has bad shaped triangular surfaces, like some very short edge, very small angle, self-intersections, etc. the volume mesh filling the boundary of triangles cannot be accomplished.

Attach a zip with your model to have a look
User avatar
escolano
Posts: 1568
Joined: Thu Sep 18, 2014 3:31 pm

Re: Mesh generation error of a thigh bone geometry

Postby escolano » Tue Jun 05, 2018 6:06 pm

By your image, the mesh error message said that the surface number 28248 cannot be meshed.
have a look to this surface an modify a little your geometry. Maybe deleting this surface and/or some problematic neighbor, collapsing very close points, creating missing parts,...

Delete the volume before, to be able to delete the surface 28248. Once manually repaired the geometry, o be closed, create again the volume and try to generate the mesh.
Marg_Barros
Posts: 5
Joined: Mon Jun 04, 2018 4:26 pm

Re: Mesh generation error of a thigh bone geometry

Postby Marg_Barros » Tue Jun 05, 2018 6:42 pm

Ok, I'll try to manually fix the surface. I can't attach the file here, it exceeds the maximum file size.
Marg_Barros
Posts: 5
Joined: Mon Jun 04, 2018 4:26 pm

Re: Mesh generation error of a thigh bone geometry

Postby Marg_Barros » Tue Jun 05, 2018 9:44 pm

I fixed the surface which was abruptally stopping the mesh generation process. Now the process finishes the surface mesh generation and outputs another error message. The error message contains 286 error messages. since I can not upload my project here, can I send you an e-mail with it?
Attachments
GiD - Thigh Bone Geometry - Mesh Errors.png
GiD - Thigh Bone Geometry - Mesh Errors.png (91.86 KiB) Viewed 2198 times
Marg_Barros
Posts: 5
Joined: Mon Jun 04, 2018 4:26 pm

Re: Mesh generation error of a thigh bone geometry

Postby Marg_Barros » Wed Jun 06, 2018 8:42 pm

What is your suggestion? When the software outputs the "Couldn't mesh at this location" message, what is the problem that usually is related to this message?

I've noticed that the software output "Couldn't map this point" for some cases. Is there any solution for this kind of problem also?
User avatar
escolano
Posts: 1568
Joined: Thu Sep 18, 2014 3:31 pm

Re: Mesh generation error of a thigh bone geometry

Postby escolano » Fri Jun 08, 2018 10:49 am

In general, if the program said "Couldn't mesh at this location" for some entity, double click on the message line to point the location, and examine the geometry (and mesh if any) on this region, and if you detect some problem (too small detail, entities overlapped, or intersection, etc) modify the geometry or some meshing parameter (assigned size or other meshing parameters).

Maybe you can upload your model zipped if do you delete some big auxiliary file, like the .msh if any or .rdr (render mesh).
Probably only the .geo is important in your case. (I don't remember the maximum size of file that could be uploaded now to this forum, maybe 10 Mb?)

If the zip file continue too big to be uploaded to this forum, you can send directly to my e-mail (escolano@cimne.upc.edu), the model or some way to download it trough dropbox, google drive, or similar.
Marg_Barros
Posts: 5
Joined: Mon Jun 04, 2018 4:26 pm

Re: Mesh generation error of a thigh bone geometry

Postby Marg_Barros » Thu Sep 13, 2018 2:58 pm

Escolano, I know it has been a while, but since I did not receive response to my lastest e-mails, I'm here to learn how did you accomplish the task (mesh the thigh bone geometry). I've tried a lot of different options in preferences but I did not reproduce your success.
In my research, I will have to mesh more femurs, thereby I need the correct settings you used.
You've sent me a model that was possible to mesh but I couldn't identify the changes you've made to achieve the meshing of the model without errors.
Can you tell me what preferences did you apply?
User avatar
escolano
Posts: 1568
Joined: Thu Sep 18, 2014 3:31 pm

Re: Mesh generation error of a thigh bone geometry

Postby escolano » Fri Sep 14, 2018 10:08 am

Your kind of models, with a geometry defined by a triangular mesh (with possible problems of self-intersecting triangles, or others) are in general difficult to be meshed, sometimes it impossible to be meshed without semi-manually fix geometrical problems (very thin triangles, very short edges, not smooth normals, etc.), applying different geometry or mesh tools (edge collapse, smoothing, join some surfaces, etc.)

About the meshing parameters, the ones used are saved with the model.
You can open the model that is able to be meshed, and see its meshing variables with the menu:

Utilities->Status...

you can also set its values as the current in use parameters with the menu:

Mesh->Mesh options from model

or when re-meshing you can set the checkbox 'Get meshing parameters from model' of the General mesh size window, then the model values will be used to generate the mesh instead the current preferences (Utilities->Preferences) values, without modify these current preferences values.

Return to “Mesh”

Who is online

Users browsing this forum: No registered users and 1 guest