CGAL users discussion list

[Rob Pieké <>]

Small follow-up ... the problem persists, but here's an updated 
crack.off which had 8 zero-area faces removed.


> Sadly, I'm not sure what more to say. I'm able to convert the geometry 
> to Nef-land, but the boolean difference generates a non-2-manifold Nef 
> result that I can't convert back to polygons.
>
> Neither geometry is convex, but they're both water-tight and do not 
> self-intersect. In total, the two objects are comprised of ~250 triangles.
>
> Even if I use the nef_3_filtered demo application, I get an assertion 
> error.
>
> nef_3_filtered loadoff crack.off loadoff obj.off diff saveoff diff.off
>
> CGAL error: assertion violation!
> Expr: itl != it->second.end()
> File: ../../include/CGAL/Nef_3/SNC_external_structure.h
> Line: 1096
> Explanation:
> terminate called after throwing an instance of 'CGAL::Assertion_exception'
>   what():  CGAL ERROR: assertion violation!
> Expr: itl != it->second.end()
> File: ../../include/CGAL/Nef_3/SNC_external_structure.h
> Line: 1096
> Abort
>
> I'm attempting to attach the offending .off files (not sure if the list 
> accepts attachments or not).
>
> Many thanks for any advice!

OFF
48 84 0

# vertices
3.88809 1.23332 4.24587
3.88789 1.23325 4.28556
3.8289 1.31099 4.24569
3.8287 1.31092 4.28538
3.15292 2.19812 4.24364
3.15271 2.19805 4.28333
3.08824 2.283 4.24344
3.08803 2.28294 4.28313
2.41225 3.17013 4.24139
2.41205 3.17007 4.28108
2.36617 3.23062 4.24125
2.36596 3.23055 4.28094
4.89165 5.15505 4.25742
4.89145 5.15499 4.29711
4.93774 5.09457 4.25756
4.93753 5.0945 4.29725
5.61372 4.20744 4.25961
5.61352 4.20737 4.2993
5.67841 4.12255 4.25981
5.6782 4.12249 4.2995
6.35439 3.23542 4.26186
6.35419 3.23536 4.30155
6.41358 3.15775 4.26204
6.41337 3.15768 4.30173
2.37423 3.23315 2.67983
2.3579 3.22801 5.84236
4.88338 5.15245 5.85853
4.89972 5.15759 2.696
4.92947 5.09197 5.85867
2.40398 3.16753 5.8425
4.9458 5.0971 2.69614
2.42032 3.17267 2.67997
6.42164 3.16029 2.70062
6.40531 3.15515 5.86314
3.87982 1.23071 5.84697
3.89616 1.23585 2.68445
6.34612 3.23282 5.86296
3.82063 1.30839 5.84679
3.83697 1.31352 2.68427
6.36246 3.23796 2.70044
5.67014 4.11995 5.86091
3.14465 2.19552 5.84474
5.60545 4.20484 5.86072
3.07997 2.2804 5.84455
5.68647 4.12509 2.69839
3.16098 2.20065 2.68222
3.0963 2.28554 2.68202
5.62179 4.20997 2.69819

# faces
3 0 1 2
3 2 1 3
3 2 3 4
3 4 3 5
3 4 5 6
3 6 5 7
3 6 7 8
3 8 7 9
3 8 9 10
3 10 9 11
3 24 25 27
3 27 25 26
3 12 13 14
3 14 13 15
3 14 15 16
3 16 15 17
3 16 17 18
3 18 17 19
3 18 19 20
3 20 19 21
3 20 21 22
3 22 21 23
3 32 33 35
3 35 33 34
3 34 33 37
3 37 33 36
3 3 21 5
3 5 21 19
3 41 40 43
3 43 40 42
3 7 17 9
3 9 17 15
3 29 28 25
3 25 28 26
3 32 35 39
3 39 35 38
3 20 2 18
3 18 2 4
3 44 45 47
3 47 45 46
3 16 6 14
3 14 6 8
3 30 31 27
3 27 31 24
3 9 15 29
3 29 15 28
3 15 13 28
3 28 13 26
3 11 9 25
3 25 9 29
3 14 8 30
3 30 8 31
3 8 10 31
3 31 10 24
3 12 14 27
3 27 14 30
3 23 21 33
3 33 21 36
3 21 3 36
3 36 3 37
3 3 1 37
3 37 1 34
3 0 2 35
3 35 2 38
3 2 20 38
3 38 20 39
3 20 22 39
3 39 22 32
3 5 19 41
3 41 19 40
3 19 17 40
3 40 17 42
3 17 7 42
3 42 7 43
3 7 5 43
3 43 5 41
3 18 4 44
3 44 4 45
3 4 6 45
3 45 6 46
3 6 16 46
3 46 16 47
3 16 18 47
3 47 18 44