CGAL users discussion list

[Peter Hachenberger <>]

Hi Rob,

I have the same problem and look into it, now. Thanks for the hint with
the zero-facets. That already might explain everything. But I should
find stuff like this during the construction.

Peter

On Wed, 2007-11-21 at 11:51 +0000, Rob Pieké wrote:
> 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!
> plain text document attachment (crack.off)
> OFF
> 48 92 0
> 
> # vertices
> 11.1346 3.16066 2.47431
> 11.1076 3.15296 2.45198
> 11.127 3.24617 2.45397
> 11.1 3.23847 2.43164
> 11.0406 4.22279 2.22174
> 11.0136 4.2151 2.19941
> 11.0323 4.31624 2.19951
> 11.0053 4.30855 2.17718
> 10.9459 5.29287 1.96728
> 10.9189 5.28517 1.94495
> 10.94 5.35945 1.95144
> 10.913 5.35175 1.92911
> 9.06654 5.70367 4.09605
> 9.03956 5.69597 4.07372
> 9.07243 5.63709 4.11188
> 9.04545 5.62939 4.08955
> 9.15883 4.66046 4.34412
> 9.13186 4.65277 4.32179
> 9.1671 4.56701 4.36634
> 9.14013 4.55932 4.34401
> 9.25351 3.59039 4.59858
> 9.22653 3.58269 4.57625
> 9.26108 3.50488 4.61891
> 9.2341 3.49718 4.59658
> 12.0013 5.66225 2.82994
> 9.85178 5.04895 1.05061
> 7.97829 5.39317 3.19522
> 10.1278 6.00647 4.97455
> 7.98419 5.32659 3.21105
> 9.85767 4.98237 1.06645
> 10.1337 5.93989 4.99038
> 12.0072 5.59567 2.84578
> 10.3223 3.80768 5.49741
> 8.17283 3.19438 3.71809
> 10.0463 2.85016 1.57348
> 12.1958 3.46346 3.35281
> 8.16527 3.27989 3.69775
> 10.0388 2.93567 1.55314
> 12.1883 3.54897 3.33247
> 10.3148 3.89319 5.47708
> 8.07886 4.25652 3.46551
> 9.95234 3.9123 1.32091
> 8.07059 4.34997 3.44329
> 9.94408 4.00575 1.29869
> 10.2284 4.86981 5.24484
> 12.1019 4.52559 3.10023
> 12.0936 4.61904 3.07801
> 10.2201 4.96326 5.22262
> 
> # faces
> 3 2 1 0
> 3 3 1 2
> 3 4 3 2
> 3 5 3 4
> 3 6 5 4
> 3 7 5 6
> 3 8 7 6
> 3 9 7 8
> 3 10 9 8
> 3 11 9 10
> 3 27 25 24
> 3 26 25 27
> 3 14 13 12
> 3 15 13 14
> 3 16 15 14
> 3 17 15 16
> 3 18 17 16
> 3 19 17 18
> 3 20 19 18
> 3 21 19 20
> 3 22 21 20
> 3 23 21 22
> 3 35 33 32
> 3 34 33 35
> 3 37 33 34
> 3 36 33 37
> 3 5 21 3
> 3 19 21 5
> 3 43 40 41
> 3 42 40 43
> 3 9 17 7
> 3 15 17 9
> 3 25 28 29
> 3 26 28 25
> 3 39 35 32
> 3 38 35 39
> 3 18 2 20
> 3 4 2 18
> 3 47 45 44
> 3 46 45 47
> 3 14 6 16
> 3 8 6 14
> 3 27 31 30
> 3 24 31 27
> 3 11 24 25
> 3 24 11 10
> 3 12 26 27
> 3 26 12 13
> 3 29 15 9
> 3 28 15 29
> 3 28 13 15
> 3 26 13 28
> 3 25 9 11
> 3 29 9 25
> 3 30 8 14
> 3 31 8 30
> 3 31 10 8
> 3 24 10 31
> 3 27 14 12
> 3 30 14 27
> 3 23 32 33
> 3 32 23 22
> 3 0 34 35
> 3 34 0 1
> 3 33 21 23
> 3 36 21 33
> 3 36 3 21
> 3 37 3 36
> 3 37 1 3
> 3 34 1 37
> 3 35 2 0
> 3 38 2 35
> 3 38 20 2
> 3 39 20 38
> 3 39 22 20
> 3 32 22 39
> 3 41 19 5
> 3 40 19 41
> 3 40 17 19
> 3 42 17 40
> 3 42 7 17
> 3 43 7 42
> 3 43 5 7
> 3 41 5 43
> 3 44 4 18
> 3 45 4 44
> 3 45 6 4
> 3 46 6 45
> 3 46 16 6
> 3 47 16 46
> 3 47 18 16
> 3 44 18 47
> plain text document attachment (obj.off)
> OFF
> 74 144 0
> 
> # vertices
> 9.44578 -5 3.01268
> 9.41455 -5 3.77741
> 9.93321 -5 4.34024
> 10.6979 -5 4.37147
> 11.2608 -5 3.85281
> 11.292 -5 3.08808
> 10.7733 -5 2.52525
> 10.0086 -5 2.49402
> 9.44578 -5.72205e-06 3.01268
> 9.41455 -5.72205e-06 3.77741
> 9.93321 -5.72205e-06 4.34024
> 10.6979 -5.72205e-06 4.37147
> 11.2608 -5.72205e-06 3.85281
> 11.292 -5.72205e-06 3.08808
> 10.7733 -5.72205e-06 2.52525
> 10.0086 -5.72205e-06 2.49402
> 9.63388 0.420709 3.09975
> 9.60913 0.420709 3.70596
> 10.0203 0.420709 4.15213
> 10.6265 0.420709 4.17689
> 11.0727 0.420709 3.76574
> 11.0974 0.420709 3.15952
> 10.6863 0.420709 2.71335
> 10.0801 0.420709 2.68859
> 9.92552 1.4515 3.11996
> 9.91254 1.4515 3.43764
> 10.128 1.4515 3.67144
> 10.4457 1.4515 3.68442
> 10.6795 1.4515 3.46896
> 10.6925 1.4515 3.15128
> 10.477 1.4515 2.91747
> 10.1593 1.4515 2.9045
> 10.1166 5 3.30036
> 10.1088 5 3.49129
> 10.2383 5 3.63182
> 10.4292 5 3.63961
> 10.5698 5 3.51012
> 10.5776 5 3.31918
> 10.4481 5 3.17866
> 10.2571 5 3.17086
> 9.99889 8.5485 3.31981
> 9.98592 8.5485 3.63749
> 10.2014 8.5485 3.87129
> 10.5191 8.5485 3.88427
> 10.7529 8.5485 3.66881
> 10.7658 8.5485 3.35113
> 10.5504 8.5485 3.11732
> 10.2327 8.5485 3.10435
> 9.63388 9.57929 3.09975
> 9.60913 9.57929 3.70596
> 10.0203 9.57929 4.15213
> 10.6265 9.57929 4.17689
> 11.0727 9.57929 3.76574
> 11.0974 9.57929 3.15952
> 10.6863 9.57929 2.71335
> 10.0801 9.57929 2.68859
> 9.44578 10 3.01268
> 9.41455 10 3.77741
> 9.93321 10 4.34024
> 10.6979 10 4.37147
> 11.2608 10 3.85281
> 11.292 10 3.08808
> 10.7733 10 2.52525
> 10.0086 10 2.49402
> 9.44578 15 3.01268
> 9.41455 15 3.77741
> 9.93321 15 4.34024
> 10.6979 15 4.37147
> 11.2608 15 3.85281
> 11.292 15 3.08808
> 10.7733 15 2.52525
> 10.0086 15 2.49402
> 10.3533 -5 3.43274
> 10.3533 15 3.43274
> 
> # faces
> 3 8 1 0
> 3 9 1 8
> 3 9 2 1
> 3 10 2 9
> 3 10 3 2
> 3 11 3 10
> 3 11 4 3
> 3 12 4 11
> 3 12 5 4
> 3 13 5 12
> 3 13 6 5
> 3 14 6 13
> 3 14 7 6
> 3 15 7 14
> 3 15 0 7
> 3 8 0 15
> 3 16 9 8
> 3 17 9 16
> 3 17 10 9
> 3 18 10 17
> 3 18 11 10
> 3 19 11 18
> 3 19 12 11
> 3 20 12 19
> 3 20 13 12
> 3 21 13 20
> 3 21 14 13
> 3 22 14 21
> 3 22 15 14
> 3 23 15 22
> 3 23 8 15
> 3 16 8 23
> 3 16 25 17
> 3 24 25 16
> 3 17 26 18
> 3 25 26 17
> 3 18 27 19
> 3 26 27 18
> 3 27 20 19
> 3 28 20 27
> 3 28 21 20
> 3 29 21 28
> 3 29 22 21
> 3 30 22 29
> 3 30 23 22
> 3 31 23 30
> 3 23 24 16
> 3 31 24 23
> 3 32 25 24
> 3 33 25 32
> 3 33 26 25
> 3 34 26 33
> 3 34 27 26
> 3 35 27 34
> 3 27 36 28
> 3 35 36 27
> 3 28 37 29
> 3 36 37 28
> 3 29 38 30
> 3 37 38 29
> 3 30 39 31
> 3 38 39 30
> 3 39 24 31
> 3 32 24 39
> 3 40 33 32
> 3 41 33 40
> 3 41 34 33
> 3 42 34 41
> 3 42 35 34
> 3 43 35 42
> 3 35 44 36
> 3 43 44 35
> 3 36 45 37
> 3 44 45 36
> 3 37 46 38
> 3 45 46 37
> 3 38 47 39
> 3 46 47 38
> 3 47 32 39
> 3 40 32 47
> 3 40 49 41
> 3 48 49 40
> 3 41 50 42
> 3 49 50 41
> 3 42 51 43
> 3 50 51 42
> 3 51 44 43
> 3 52 44 51
> 3 52 45 44
> 3 53 45 52
> 3 53 46 45
> 3 54 46 53
> 3 54 47 46
> 3 55 47 54
> 3 47 48 40
> 3 55 48 47
> 3 56 49 48
> 3 57 49 56
> 3 57 50 49
> 3 58 50 57
> 3 58 51 50
> 3 59 51 58
> 3 59 52 51
> 3 60 52 59
> 3 60 53 52
> 3 61 53 60
> 3 61 54 53
> 3 62 54 61
> 3 62 55 54
> 3 63 55 62
> 3 63 48 55
> 3 56 48 63
> 3 64 57 56
> 3 65 57 64
> 3 65 58 57
> 3 66 58 65
> 3 66 59 58
> 3 67 59 66
> 3 67 60 59
> 3 68 60 67
> 3 68 61 60
> 3 69 61 68
> 3 69 62 61
> 3 70 62 69
> 3 70 63 62
> 3 71 63 70
> 3 71 56 63
> 3 64 56 71
> 3 72 0 1
> 3 72 1 2
> 3 72 2 3
> 3 72 3 4
> 3 72 4 5
> 3 72 5 6
> 3 72 6 7
> 3 72 7 0
> 3 73 65 64
> 3 73 66 65
> 3 73 67 66
> 3 73 68 67
> 3 73 69 68
> 3 73 70 69
> 3 73 71 70
> 3 73 64 71