# Topology issue with projection 2D algorithm

Hey,

I have some problems with the projection 2D mesh algorithm. I'm trying to mesh some kind of pipe truncated by a sphere at one of his end. I would like to use quadrangles with prisms on this axis but I have some issues with the projection 2D that says "Unexpected geometry. Topology of source and target faces seems different.". Anybody has an idea on how to deal with this ?

For the mesh I'm using the 3D radial prism algorithm, for the straight face I have quadrangles with a base vertex enforced at one edge. For the curved face I use (I'd like to use) the projection 2D to get the mesh from the straight face.

The pyhthon is attached below.

Thanks,

Hi,

projection fails as faces are really different, "What Is" says one has 3 edges and the other has 4 edges. An excess edge comes from a degenerated edge at apex of the sphere.

I made 2 changes in your script to make it work:

1) Rotate the sphere to move its apex out of Cut_1.

2) Then the 2D projection passes OK but the mesh is irregular. To fix it I applied SmoothParametricObject() to the mesh on Face_1 before computing 3D mesh.

Enjoy!

St.Michael

Dear,

I tried to compute the mesh using the attached python script, but there is always an error like below:

"Invalid input mesh. Incompatible non-structured sub-meshes" for the Prism_3D_4 algorithm.

I am trying to leanr something about the projection algorithm from your case.

I am using Salome 7.8.0

Thank you in advance.

Best Regards,

Bill