Potential implementation of mesh warning system

[keiyamamo]

Hi @johannesring @jorgensd

This is not a PR (yet) but I would like to discuss how we should implement warning system in the meshing pipeline.
By setting the tetgen.Verbose = 1, I know we could get the following information (printed in the terminal). This could potentially be used to detect “low-quality” mesh, but we would need some threshold for that. Do you have suggestions for what metrics and what threshold should be used?

Additionally, I could not figure out how to obtain printed information as python objects. I used sys.stdout but that did not work. It might be because those information come from tetgen through VMTK. If you have some idea how to do that, I would appreciate it.

Mesh quality statistics:

  Smallest volume:       2.4084e-05   |  Largest volume:       0.00050203
  Shortest edge:           0.057295   |  Longest edge:            0.24617
  Smallest aspect ratio:     1.2444   |  Largest aspect ratio:     12.469
  Smallest facangle:         22.997   |  Largest facangle:       125.1049
  Smallest dihedral:         8.2464   |  Largest dihedral:       164.5351

  Aspect ratio histogram:
         < 1.5       :       372      |      6 - 10         :        57
     1.5 - 2         :      2613      |     10 - 15         :         1
       2 - 2.5       :      1633      |     15 - 25         :         0
     2.5 - 3         :       483      |     25 - 50         :         0
       3 - 4         :       240      |     50 - 100        :         0
       4 - 6         :       129      |    100 -            :         0
  (A tetrahedron's aspect ratio is its longest edge length divided by its
    smallest side height)

  Face angle histogram:
      0 -  10 degrees:         0      |     90 - 100 degrees:      1088
     10 -  20 degrees:         0      |    100 - 110 degrees:       350
     20 -  30 degrees:        76      |    110 - 120 degrees:        41
     30 -  40 degrees:      2370      |    120 - 130 degrees:         5
     40 -  50 degrees:      5583      |    130 - 140 degrees:         0
     50 -  60 degrees:      3430      |    140 - 150 degrees:         0
     60 -  70 degrees:      2988      |    150 - 160 degrees:         0
     70 -  80 degrees:      4490      |    160 - 170 degrees:         0
     80 -  90 degrees:      2497      |    170 - 180 degrees:         0

  Dihedral angle histogram:
       0 -  5 degrees:         0      |     80 - 110 degrees:      3818
       5 - 10 degrees:         2      |    110 - 120 degrees:       670
      10 - 20 degrees:       151      |    120 - 130 degrees:       380
      20 - 30 degrees:       291      |    130 - 140 degrees:       219
      30 - 40 degrees:       899      |    140 - 150 degrees:       149
      40 - 50 degrees:      1931      |    150 - 160 degrees:        87
      50 - 60 degrees:      1869      |    160 - 170 degrees:        33
      60 - 70 degrees:       385      |    170 - 175 degrees:         0
      70 - 80 degrees:       172      |    175 - 180 degrees:         0

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 82.01%. Comparing base (6341898) to head (1c8d97f).

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #219   +/-   ##
=======================================
  Coverage   82.00%   82.01%           
=======================================
  Files          32       32           
  Lines        4013     4014    +1     
=======================================
+ Hits         3291     3292    +1     
  Misses        722      722           

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[keiyamamo]

I think printing out this mesh statistics would be enough for now. We can potentially implement mesh warning system as future update.

[johannesring]

@keiyamamo - please see PR #222.