3D tesr meshing with control over discretization per grain

[sinaMTEX]

Dear Prof. Romain and NEPER community,
I want to generate a polycrystal with cubic grains, where each grain is divided by 3X3X3 voxels. The figure below shows what I want to produce:

(in the figure, each grain is divided by 4X4X4 voxels, in my case, 27 discretizations per grain are needed.)

I run the following commands in NEPER for polycrystal generation and visualization:

$ neper -T -n from_morpho -morpho 'cube(8,8,8)' -domain 'cube(1,1,1)' -o test9 -format tesr

========================    N   e   p   e   r    =======================
Info   : A software package for polycrystal generation and meshing.
Info   : Version 4.10.0
Info   : Built with: gsl|muparser|opengjk|openmp|nlopt|libscotch (full)
Info   : Running on 16 threads.
Info   : <https://neper.info>
Info   : Copyright (C) 2003-2024, and GNU GPL'd, by Romain Quey.
Info   : No initialization file found (`/home/sina/.neperrc').
Info   : ---------------------------------------------------------------
Info   : MODULE  -T loaded with arguments:
Info   : [ini file] (none)
Info   : [com line] -n from_morpho -morpho cube(8,8,8) -domain
         cube(1,1,1) -o test9 -format tesr
Info   : ---------------------------------------------------------------
Info   : Reading input data...
Info   : Creating domain...
Info   : Creating tessellation...
Info   :   - Running tessellation...
Info   : Generating crystal orientations...
Info   : Rasterizing tessellation...
Info   : Writing results...
Info   :     [o] Writing file `test9.tesr'...
Info   :     [o] Wrote file `test9.tesr'.
Info   : Elapsed time: 0.026 secs.
========================================================================

$ neper -V test9.tesr -print img_test9

========================    N   e   p   e   r    =======================
Info   : A software package for polycrystal generation and meshing.
Info   : Version 4.10.0
Info   : Built with: gsl|muparser|opengjk|openmp|nlopt|libscotch (full)
Info   : Running on 16 threads.
Info   : <https://neper.info>
Info   : Copyright (C) 2003-2024, and GNU GPL'd, by Romain Quey.
Info   : No initialization file found (`/home/sina/.neperrc').
Info   : ---------------------------------------------------------------
Info   : MODULE  -V loaded with arguments:
Info   : [ini file] (none)
Info   : [com line] test9.tesr -print img_test9
Info   : ---------------------------------------------------------------
Info   :   - Reading arguments...
Info   : Loading raster tessellation...
Info   :     [i] Parsing file `test9.tesr'...
Info   :     [i] Parsed file `test9.tesr'.
Info   : Printing image...
Info   :   - Printing raster tessellation...
Info   :     > Converting to mesh...
Info   :     > Reducing data...
Info   :       . 3D...
Info   :       . 2D...
Info   :       . Number of 3D elt edges reduced by  50% (to 4800).
Info   :   - Generating png file (1200x900 pixels)...
Info   :     [o] Writing file `img_test9.png'...
Info   :     [o] Wrote file `img_test9.png'.
Info   : Printing scale...
Info   : Elapsed time: 1.183 secs.
========================================================================

Here is the generated polycrystal:

However, when it comes to meshing, the following error comes up:

$ neper -M test9.tesr -elt hex

========================    N   e   p   e   r    =======================
Info   : A software package for polycrystal generation and meshing.
Info   : Version 4.10.0
Info   : Built with: gsl|muparser|opengjk|openmp|nlopt|libscotch (full)
Info   : Running on 16 threads.
Info   : <https://neper.info>
Info   : Copyright (C) 2003-2024, and GNU GPL'd, by Romain Quey.
Info   : No initialization file found (`/home/sina/.neperrc').
Info   : ---------------------------------------------------------------
Info   : MODULE  -M loaded with arguments:
Info   : [ini file] (none)
Info   : [com line] test9.tesr -elt hex
Info   : ---------------------------------------------------------------
Info   : Reading input data...
Info   :   - Reading arguments...
Info   : Loading input data...
Info   :   - Loading raster tessellation...
Info   :     [i] Parsing file `test9.tesr'...
Info   :     [i] Parsed file `test9.tesr'.
Info   : Meshing...
Info   :   - Preparing... 

Info   :   - 3D meshing... 
Info   :   - Switching mesh to order 2...
Segmentation fault (core dumped)
========================================================================

In this regard, I have two questions:
(1) What did I miss in the command meshing the generated polycrystal, and how can I have 3X3X3 discretizations inside the grains? Could you please share the code?
(2) Please have a look at the generated polycrystal. It is clear that all the grains are not the same size--some cubic grains are bigger than others. How can I get uniform grains?

I would appreciate it if you could help me. Thanks in advance for your time, consideration, and guidance!

Best regards
Sina

[rquey]

It is because the tesr is defined on the default grid of 20 x 20 x 20 voxels. To get 3 x 3 x 3 voxels per grain, use -tesrsize 8*3 (or -tesrsize 24...). See -tesrsize.

neper -T -n from_morpho -morpho 'cube(8,8,8)' -domain 'cube(1,1,1)' -o test9 -tesrsize 8*3 -format tess,tesr
neper -V test9.tesr -datavoxedgerad 0.002 -print img_test9

To get a mesh, use the tess:

neper -M test9.tess -cl "1/(8*3)" -elt hex
neper -V test9.tess,test9.msh -dataelt3dedgerad 0.002 -print img_test9_msh

It is essentially the same data. Only the format is different.

[sinaMTEX]

Thank you so much for your response.

Best regards,
Sina