[vtkusers] Convex hull of spherical point cloud has holes
Amit
amit112amit at yahoo.co.in
Wed Aug 9 14:18:31 EDT 2017
Dear all.
I have a point cloud made up of points lying on surface of a unit sphere
stored in a vtkPolyData. I want to get the convex hull of this point
cloud using the vtkDelaunay3D filter. Then using vtkDataSetSurfaceFilter
I want to extract the surface of the convex hull. This way, I can get a
triangulation of the point cloud as a hollow spherical shell. Kindly
open the attached UnstructuredGrid file in Paraview. It represents the
output of vtkDelaunay3D filter made up of tetrahedrons. But the surface
of the convex-hull has some missing triangles. Using the SpreadSheet
View, I can see that cells with Ids 60, 61, 64 have triangular faces in
the missing region. Hence, I would not have expected these "hole" in the
surface. Can somebody explain why the triangles are not being rendered?
When I extract surface from this unstructured grid I get a spherical
shell with missing triangles as holes.
Regards,
Amit
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# vtk DataFile Version 4.1
vtk output
ASCII
DATASET UNSTRUCTURED_GRID
POINTS 72 float
0.970744 0.153449 -0.184687 0.763096 0.298245 -0.573353 0.78863 0.579535 -0.205429
0.492756 0.674421 -0.549861 0.395823 0.337832 -0.853928 0.0749938 0.656482 -0.750605
-0.217123 0.972747 -0.0813657 0.139611 0.917425 -0.372613 -0.290352 0.810005 -0.509498
0.290441 0.809973 0.509498 0.21723 0.972723 0.0813657 -0.13951 0.91744 0.372613
0.63989 0.511667 0.573357 0.89625 0.393107 0.205433 0.618346 0.763896 0.184691
-0.618262 0.763964 -0.184691 -0.639834 0.511737 -0.573357 -0.896207 0.393206 -0.205433
-0.0749218 0.65649 0.750605 -0.492682 0.674475 0.549861 -0.395786 0.337876 0.853928
-0.788567 0.579622 0.205429 -0.970727 0.153556 0.184687 -0.763064 0.298329 0.573353
0.0487208 0.263327 0.963476 -0.252412 -0.0894677 0.963475 0.203683 -0.173859 0.963476
0.490499 0.173821 0.853931 0.605995 -0.263363 0.750607 0.830452 0.089436 0.549865
-0.337774 -0.763911 0.549862 -0.0947193 -0.511697 0.853929 -0.531079 -0.393127 0.750603
0.123169 -0.809995 0.573356 -0.107685 -0.972729 0.20543 0.35238 -0.917452 0.18469
0.556235 -0.656517 0.509499 0.733788 -0.674489 0.0813671 0.86428 -0.337901 0.372615
-0.846679 -0.153456 0.509495 -0.951019 -0.298235 0.0813625 -0.724773 -0.579539 0.372611
-0.123258 -0.809982 -0.573356 0.107578 -0.972741 -0.20543 -0.35248 -0.917413 -0.18469
-0.556307 -0.656456 -0.509499 -0.733862 -0.674408 -0.0813671 -0.864317 -0.337807 -0.372615
0.0946632 -0.511707 -0.853929 0.531036 -0.393186 -0.750603 0.33769 -0.763949 -0.549862
0.950986 -0.298339 -0.0813625 0.724709 -0.579618 -0.372611 0.846663 -0.153549 -0.509495
-0.203702 -0.173837 -0.963476 -0.0486919 0.263332 -0.963476 0.252402 -0.0894953 -0.963475
-0.606024 -0.263296 -0.750607 -0.830442 0.0895271 -0.549865 -0.490479 0.173875 -0.853931
-0.3035 0.525748 -0.794655 -0.303558 -0.525714 -0.794655 -0.982246 5.38771e-05 -0.187595
0.607064 -3.32895e-05 -0.794653 0.982246 -5.38765e-05 0.187595 0.491077 -0.850678 -0.187591
-0.491171 -0.850624 0.187591 -0.607064 3.32923e-05 0.794653 0.3035 -0.525748 0.794655
0.303558 0.525714 0.794655 -0.491077 0.850678 0.187591 0.491171 0.850624 -0.187591
CELLS 179 895
4 46 47 40 66
4 1 51 2 71
4 11 10 9 18
4 12 10 9 14
4 2 3 1 71
4 3 4 1 5
4 30 31 25 32
4 31 33 30 68
4 23 21 19 70
4 10 12 9 18
4 29 18 12 71
4 8 15 5 71
4 10 14 12 71
4 3 5 1 71
4 36 38 18 68
4 58 54 57 59
4 8 5 7 71
4 23 22 21 70
4 18 12 9 69
4 51 49 1 53
4 13 14 2 71
4 3 7 5 71
4 6 8 7 71
4 2 51 13 71
4 15 21 17 22
4 47 46 42 66
4 20 19 18 23
4 12 14 13 71
4 18 27 26 29
4 40 58 22 71
4 56 5 55 60
4 22 51 40 71
4 11 6 10 70
4 10 18 11 70
4 6 15 10 70
4 18 19 11 70
4 42 57 47 58
4 70 23 22 71
4 42 49 1 51
4 30 40 36 51
4 12 18 10 71
4 21 22 15 70
4 10 70 15 71
4 37 42 36 51
4 27 28 26 29
4 5 42 1 71
4 39 23 32 40
4 24 25 18 26
4 50 49 42 51
4 20 23 18 25
4 18 24 20 25
4 51 29 38 64
4 30 36 23 68
4 39 40 32 41
4 24 26 18 27
4 13 27 12 29
4 27 28 12 29
4 12 28 13 29
4 12 27 13 28
4 35 34 33 36
4 12 27 18 29
4 28 27 13 29
4 13 51 29 71
4 25 30 23 68
4 29 12 13 71
4 6 15 8 71
4 38 18 29 71
4 38 28 29 68
4 58 16 15 60
4 29 28 26 68
4 36 30 33 68
4 30 25 23 32
4 32 25 23 67
4 23 39 22 40
4 25 31 30 68
4 38 36 28 68
4 40 30 32 41
4 37 50 42 51
4 13 2 0 51
4 22 17 15 58
4 46 44 42 66
4 7 10 6 71
4 26 31 25 68
4 32 23 30 40
4 38 37 36 51
4 22 58 15 71
4 34 30 33 66
4 18 36 23 38
4 51 40 42 66
4 23 25 20 67
4 0 2 1 51
4 15 6 10 71
4 36 30 23 40
4 15 58 5 71
4 58 42 5 71
4 51 50 49 52
4 45 46 42 47
4 42 58 40 71
4 40 47 42 66
4 33 42 34 66
4 33 36 34 42
4 40 51 42 71
4 58 15 5 60
4 36 35 34 43
4 37 35 36 43
4 34 42 36 43
4 36 42 37 43
4 54 48 42 61
4 15 17 16 58
4 45 44 42 46
4 41 46 40 66
4 40 51 30 66
4 30 41 40 66
4 47 40 42 58
4 59 58 54 60
4 42 49 48 56
4 43 42 37 50
4 48 49 42 50
4 5 4 1 49
4 1 42 5 49
4 50 51 37 52
4 18 38 23 51
4 23 38 36 51
4 36 40 23 51
4 23 40 22 51
4 42 51 1 71
4 29 51 38 71
4 0 51 1 53
4 43 37 35 65
4 52 49 51 53
4 48 54 42 56
4 55 59 54 60
4 4 49 5 56
4 5 55 4 56
4 54 56 55 60
4 5 49 42 56
4 5 15 8 60
4 45 47 42 57
4 54 57 42 58
4 18 51 23 71
4 51 22 23 71
4 51 18 38 71
4 15 16 8 60
4 59 16 58 60
4 5 56 42 60
4 56 54 42 60
4 54 58 42 60
4 42 58 5 60
4 45 57 42 61
4 57 54 42 61
4 58 47 40 62
4 17 58 22 62
4 58 40 22 62
4 1 53 49 63
4 49 4 1 63
4 56 4 49 63
4 29 51 13 64
4 13 51 0 64
4 50 37 43 65
4 52 37 50 65
4 42 43 34 66
4 43 44 34 66
4 44 43 42 66
4 30 51 36 66
4 51 42 36 66
4 30 36 33 66
4 36 42 33 66
4 23 39 32 67
4 23 36 18 68
4 29 26 18 68
4 18 38 29 68
4 18 25 23 68
4 26 25 18 68
4 24 27 18 69
4 18 27 12 69
4 23 19 18 70
4 15 70 22 71
4 23 70 18 71
4 18 70 10 71
CELL_TYPES 179
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POINT_DATA 72
SCALARS PointIds vtkIdType
LOOKUP_TABLE default
0 1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16 17
18 19 20 21 22 23 24 25 26
27 28 29 30 31 32 33 34 35
36 37 38 39 40 41 42 43 44
45 46 47 48 49 50 51 52 53
54 55 56 57 58 59 60 61 62
63 64 65 66 67 68 69 70 71
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