View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0023894 | Community | OCCT:Visualization | public | 2013-04-11 18:58 | 2013-12-19 13:55 |
| Reporter | Pawel | Assigned To | Pawel | ||
| Priority | normal | Severity | minor | ||
| Status | closed | Resolution | fixed | ||
| Platform | Windows | OS | VC++ 2008 | ||
| Product Version | 6.6.0 | ||||
| Target Version | 6.7.0 | Fixed in Version | 6.7.0 | ||
| Summary | 0023894: Voxel_BooleanOperation (Cut) gives incorrect results | ||||
| Description | Performing Voxel_BooleanOperation::Cut gives incorrect results while cutting a box with a sphere. For instance, for the code given below in Voxel_BooleanOperation::Cut, for ix = 28, iy = 52, iz = 40 the line 131 Standard_Boolean value2 = theVoxels2.Get(ix, iy, iz); returns 0, meaning there is no material at this place, while this position is definitely located inside the sphere. Consequently, the voxels from the box are not substracted/cut. Consult the images to see the problem. On the first one (Voxel_BoolDS_Cut_SphereBox01.png) no voxels are cut near one of the edges of the box - pay attention to the gray strip. On the second one (Voxel_BoolDS_Cut_SphereBox02.png) many gray strips are visible - no material is detected inside the sphere. | ||||
| Steps To Reproduce | I'm not sure how to reproduce the problem in DRAW therefore only C++ reproducer: TopoDS_Shape shape = BRepPrimAPI_MakeSphere(gp_Pnt(11,8,11), 7); TopoDS_Shape shape1 = BRepPrimAPI_MakeBox(gp_Pnt(7, 10, 10), 5, 3, 3); Standard_Real delfection = 0.1; Standard_Integer nbx = 200, nby = 200, nbz = 200; Voxel_BoolDS theVoxels(0,0,0, 50, 50, 50, nbx, nby, nbz); Voxel_BoolDS theVoxels1(0,0,0, 50, 50, 50, nbx, nby, nbz); Standard_Integer nbThreads = 1; Voxel_FastConverter fcp(shape, theVoxels, delfection, nbx, nby, nbz, nbThreads); Standard_Integer progress; fcp.Convert(progress); fcp.FillInVolume(1); Voxel_FastConverter fcp1(shape1, theVoxels1, delfection, nbx, nby, nbz, nbThreads); progress = 0; fcp1.Convert(progress); fcp1.FillInVolume(1); Voxel_BooleanOperation op; Standard_Boolean result = op.Cut(theVoxels1, theVoxels); ========================== You can also try using a bigger box: TopoDS_Shape shape1 = BRepPrimAPI_MakeBox(gp_Pnt(5, 10, 10), 10, 20, 30); to see the problem occurs frequently. | ||||
| Tags | No tags attached. | ||||
| Test case number | v3d voxel(012) | ||||
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Voxel_BoolDS_Cut_SphereBox02.png (54,267 bytes) |
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Voxel_BoolDS_Cut_SphereBox01.png (50,178 bytes) |
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Hi Pawel, Thank you for the full information on the bug. I put a break point at the line 131 of Voxel_BooleanOperation::Cut() - it returns 1 for the voxel (28, 52, 40). Also, I noticed that you subtract a sphere from the box. It would be better to subtract a box from the sphere because the sphere is greater and contains the whole box (I attach a picture). I made the tests on Visual Studio 2010, 32bits. Let me know please if the bug still presents in your environment and I will check it Visualo Studio 2008, 64bits. |
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SphereMinusBox.png (48,105 bytes) |
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In the picture SphereMinusBox I used VoxelDemo - a free sample application. It allows visualization of voxels displaying only a part of them (clipping the view by a plane). In the picture you may see a sphere and subtracted voxels from the place where the box is located. Visually - the operation is performed without a defect. |
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Dear vro, thanks for your feedback! I have double-checked and here are the results: My system is Win7 x64, VS2008, I used OCCT 660 (current master) as 32 and 64 bit. I took two shapes: TopoDS_Shape shape = BRepPrimAPI_MakeSphere(gp_Pnt(11,8,11), 7); TopoDS_Shape shape1 = BRepPrimAPI_MakeBox(gp_Pnt(7, 10, 10), 5, 3, 3); I subtracted the sphere from the box which should produce 'void' but I still get this strip as depicted. I also noticed that Voxel_FastConverter::FillInVolume never fills the voxel (28, 52, 40) of the sphere. The line 336: ((Voxel_BoolDS*)myVoxels)->Set(ix, iy, iz, inner); is called for ix = 29 but not sooner. This is actually the reason why the line 131: Standard_Boolean value2 = theVoxels2.Get(ix, iy, iz); in Voxel_BooleanOperation::Cut returns '0'. So I guess there is something wrong here but at this time I can't say more... |
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Dear vro, please consult my comment above. I guess there is some problem with the filling of the sphere. I might be wrong. I'm a bit puzzled by the fact you weren't able to reproduce the problem. Maybe because of the different VS version... |
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When I change the deflection to 0.001 no strip occurs... |
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Another observation... I suspect the problem might be caused by the method Voxel_FastConverter::ComputeVoxelsNearTriangle. I have noticed that for the code TopoDS_Shape shape = BRepPrimAPI_MakeSphere(gp_Pnt(11,8,11), 7); Standard_Real delfection = 0.1; Standard_Integer nbx = 200, nby = 200, nbz = 200; Voxel_BoolDS theVoxels(0,0,0, 50, 50, 50, nbx, nby, nbz); Standard_Integer nbThreads = 1; Voxel_FastConverter fcp(shape, theVoxels, delfection, nbx, nby, nbz, nbThreads); Standard_Integer progress; fcp.Convert(progress); the method finds and sets - (((Voxel_BoolDS*) myVoxels)->Set(ix, iy, iz, Standard_True);) - for instance six surface voxels for the sphere at the specified voxel-coordinate (28,50): 28,50,28 28,50,31 28,50,30 28,50,57 28,50,56 28,50,59 which is obviously wrong because only two surface voxels should be found! I guess, this might lead to incorrect computation in Voxel_FastConverter::FillInVolume. Voxel_FastConverter::ComputeVoxelsNearTriangle might use an incorrect precision value somewhere because changing the meshing deflection affects the behaviour described above. However, not sure... |
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OK, I think I have found the root cause of the problem (although not implemented the solution yet). Voxel_FastConverter::Convert calls ComputeVoxelsNearTriangle which "Refuses voxels for whom distance from their center to plane of triangle is greater than half of diagonal". In this approach, a triangle-sphere test (sphere has the radius of half of diagonal) - line 460, Voxel_FastConverter.cxx - is performed to decide whether a triangle intersects a voxel. This is wrong in my my opinion because a voxel is considered to be a cube, isn't it? This is the reason why too many voxels are set to Standard_True (see my note above 0024429). Thus a triangle-box intersection test should be used in ComputeVoxelsNearTriangle to give more accurate results. |
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Voxel_BoolDS_Cut_SphereBox02_Fixed.png (77,214 bytes) |
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Dear Vlad, branch CR23894 has been pushed and is ready for review. I have implemented an alternative method converting TopoDS_Shape to voxels. The new method computes triangle-box intersection to judge whether a voxel intersects the triangulation or not. I guess the old implementation is wrong because it checks the interference of the triangulation with a sphere. I think it is also slower (at least this is what I observed). However, I leave the decision whether to keep it or not to you. The triangle-box intersection code was derived from Pierre Terdiman's implementation (public domain) used in OPCODE (http://www.codercorner.com/Opcode.htm). To see the result of the new method for the box-sphere cut refer to the attached picture(Voxel_BoolDS_Cut_SphereBox02_Fixed.png). |
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Reviewed! |
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Dear BugMaster, Branch CR23894 (and products from GIT master) was compiled on Linux and Windows platforms and tested. SHA-1: 5d043261fc31757919c30ba423d6f9de6d1e4750 Number of compiler warnings: occt component : Linux: 2 (2 on master) Windows: 7 (7 on master) products component : Linux: 0 (0 on master) Windows: 63 (63 on master) Regressions: No regressions Improvements: No improvements Testing cases: v3d voxel - OK. Testing on Linux: Total MEMORY difference: 366333156 / 366313324 Total CPU difference: 40875.56000000081 / 43688.52000000147 Testing on Windows: Total MEMORY difference: 421059316 / 423437552 Total CPU difference: 39796.328125 / 31295.625 There are not differences in images found by testdiff. |
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occt: master f03671a0 2013-06-13 11:19:29 Details Diff |
0023894: Voxel_BooleanOperation (Cut) gives incorrect results Implemented a new method using separating axis theorem to compute triangle-box intersection. Based on the intersection result the decision whether to set the voxel is made. Adjustment of lines (removal of extra-spaces). Adding test cases for voxel testing |
Affected Issues 0023894 |
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| mod - src/Voxel/Voxel_FastConverter.cdl | Diff File | ||
| mod - src/Voxel/Voxel_FastConverter.cxx | Diff File | ||
| mod - tests/v3d/grids.list | Diff File | ||
| add - tests/v3d/voxel/A1 | Diff File | ||
| add - tests/v3d/voxel/A2 | Diff File | ||
| add - tests/v3d/voxel/A3 | Diff File | ||
| add - tests/v3d/voxel/A4 | Diff File | ||
| add - tests/v3d/voxel/A5 | Diff File | ||
| add - tests/v3d/voxel/A6 | Diff File | ||
| add - tests/v3d/voxel/A7 | Diff File | ||
| add - tests/v3d/voxel/A8 | Diff File | ||
| add - tests/v3d/voxel/A9 | Diff File | ||
| add - tests/v3d/voxel/B1 | Diff File | ||
| add - tests/v3d/voxel/B2 | Diff File | ||
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2013-04-11 18:58 | Pawel | New Issue | |
| 2013-04-11 18:58 | Pawel | Assigned To | => san |
| 2013-04-11 18:58 | Pawel | File Added: Voxel_BoolDS_Cut_SphereBox01.png | |
| 2013-04-11 19:07 | Pawel | Assigned To | san => vro |
| 2013-04-11 19:07 | Pawel | Description Updated | |
| 2013-04-11 19:07 | Pawel | Steps to Reproduce Updated | |
| 2013-04-11 19:08 | Pawel | File Added: Voxel_BoolDS_Cut_SphereBox02.png | |
| 2013-04-11 19:10 | Pawel | Description Updated | |
| 2013-04-11 19:12 | Pawel | Description Updated | |
| 2013-04-11 19:12 | Pawel | Steps to Reproduce Updated | |
| 2013-04-11 19:14 | Pawel | File Deleted: Voxel_BoolDS_Cut_SphereBox01.png | |
| 2013-04-11 19:14 | Pawel | File Added: Voxel_BoolDS_Cut_SphereBox01.png | |
| 2013-04-11 19:15 | Pawel | Description Updated | |
| 2013-04-11 19:17 | Pawel | Steps to Reproduce Updated | |
| 2013-05-08 16:39 | vro | Note Added: 0024343 | |
| 2013-05-08 16:39 | vro | Assigned To | vro => Pawel |
| 2013-05-08 16:39 | vro | Status | new => feedback |
| 2013-05-08 16:40 | vro | File Added: SphereMinusBox.png | |
| 2013-05-08 16:43 | vro | Note Added: 0024344 | |
| 2013-05-08 18:56 | Pawel | Note Added: 0024349 | |
| 2013-05-08 19:00 | Pawel | Note Added: 0024350 | |
| 2013-05-08 19:00 | Pawel | Assigned To | Pawel => vro |
| 2013-05-08 19:00 | Pawel | Status | feedback => assigned |
| 2013-05-08 19:20 | Pawel | Note Added: 0024351 | |
| 2013-05-17 18:51 | Pawel | Note Added: 0024429 | |
| 2013-05-21 19:12 | Pawel | Note Added: 0024456 | |
| 2013-06-07 01:13 | Pawel | File Added: Voxel_BoolDS_Cut_SphereBox02_Fixed.png | |
| 2013-06-07 01:32 | Pawel | Note Added: 0024682 | |
| 2013-06-07 01:32 | Pawel | Status | assigned => resolved |
| 2013-06-10 11:02 | vro | Note Added: 0024707 | |
| 2013-06-10 11:02 | vro | Status | resolved => reviewed |
| 2013-06-10 12:47 |
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Assigned To | vro => mkv |
| 2013-06-11 12:30 |
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Note Added: 0024729 | |
| 2013-06-11 12:31 |
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Test case number | => v3d voxel(012) |
| 2013-06-11 12:31 |
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Assigned To | mkv => bugmaster |
| 2013-06-11 12:31 |
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Status | reviewed => tested |
| 2013-06-14 12:18 | Pawel | Changeset attached | => occt master f03671a0 |
| 2013-06-14 12:18 | Pawel | Assigned To | bugmaster => Pawel |
| 2013-06-14 12:18 | Pawel | Status | tested => verified |
| 2013-06-14 12:18 | Pawel | Resolution | open => fixed |
| 2013-12-19 13:53 | bugmaster | Status | verified => closed |
| 2013-12-19 13:55 | bugmaster | Fixed in Version | => 6.7.0 |
