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Create a circle, rotate copy by 10 degrees, then connect sides on one quarter with the create facet command, delete the unnecessary three quarters, then select the slice and copy rotate 35 times.

Hello Chao, it's Roberto here.

I am not sure whether Marton created it with CAD or took the one I had created before using the editing features of Molflow+. It doesn't look like a CAD model, since this type of model, in STL, would have many facets left triangular, while in this case they look all with 4 vertices except those at the pole, if I may say so.

See this for sequence (one of the many possible)... 5degx5deg mesh on sphere:

  https://www.dropbox.com/s/rd30w5mdewzki02/Create_Hemisphere_4Chao.pptx?dl=0

Sequentially:

- Generate tube, select 1/4 vertices on circular opening;

- Generate facet with these vertices;

- Remove all other facets other than last one created;

- Rotate this facet about the Y axis by -5 deg, and "copy" to new facet;

- Create transition facets between these two facets;

- Remove unnecessary facets and vertices;

- Correct number of vertices of facet "at the pole"... should have only 3 vertices, not 4;

- Select facets and rotate by -5 deg (copying to new facets), then repeate selecting all facets and rotating by 10 deg (copying to new facets)... then select all facets again and rotate/copy by -20 deg a suitable number of times until 1/4 sphere is created;

- You can see on last slide that I've defined one formula calculating the % difference between the total area of this tasselated 1/4 sphere and a real 1/4 sphere with unitary radius (whose area is pi).. it is smaller by 0.15% only... so a good approximation of a real sphere;

- If you want to create a full 1/2 sphere you siply select all facets and rotate/copy about the Y axis by -180, and in case you need a full sphere then select the 1/2 sphere and rotate/copy about the X axis.

- Finally, in case you'd want to have the facets ordered in a different way, then you should copy only "slices" of the sphere, like along the "longitude" or "latitude"... it takes a while to do it but I've done it already.

Don't forget, at each step of the sequence, to SAVE your file, because the rotate/copy command does not have undo... although you can deleted unnecessary facets and vertices.

  Hope it helps...