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IDProjectCategoryView StatusDate SubmittedLast Update
0028833Open CASCADE[OCCT] OCCT:Modeling Algorithmspublic2017-06-09 12:452019-10-25 14:13
Reporteremv
Assigned Tomsv
PriorityhighSeverityminor
StatusassignedResolutionopen
PlatformOSOS Version
Product Version[OCCT] 7.1.0
Target Version[OCCT] UnscheduledFixed in Version
Summary0028833: Modeling Algorithms - Unstable result of intersection of the faces
DescriptionThe result of intersection of two faces is unstable:
1. The intersection gives different results on Linux and Windows platforms (deviation about 0.001);
2. Different order of the faces also gives different intersection results (deviation is also about 0.001);
3. Variations of the UV sampling of the surfaces also gives very different results:
a) for the 15x15 sampling the intersection gives 7 curves for direct order and only 5 curves for reverse order of faces;
b) for the 100x100 sampling the intersection gives only 4 curves for direct order and also 4 curves for the reverse order of faces, but these 4 curves are different (the gaps are in the different places).

The case has been detected during fixing the issue 0028599 in the test case bugs modalg_6 bug26938_*.
The intersection difference with the 15x15 sampling can be reproduced in the git branch CR28599.
Steps To Reproducebrestore [locate_data_file bug26938.brep] a
explode a
explode a_1 f; copy a_1_1 f1
explode a_2 f; copy a_2_1 f2
don f1 f2

# master
bopcurves f1 f2 -2d
# Tolerance Reached=8.7721154144228939e-005
# 7 curve(s) found.

bopcurves f2 f1 -2d
# Tolerance Reached=1.1061046409178104e-006
# 7 curve(s) found.

TagsNo tags attached.
Test case number
Attached Files

Relationships
 related to 0028599 closed apn Open CASCADE Replacement of old Boolean operations with new ones in BRepProj_Projection algorithm related to 0028802 closed bugmaster Open CASCADE The tolerance reached by approximator is used in creation of an edge, it is incorrect related to 0026463 assigned nbv Open CASCADE The result of intersection between two faces depends on the order of arguments child of 0029133 closed bugmaster Open CASCADE Unstable test cases

 Notes git (administrator) 2017-11-30 16:39 Branch CR28833 has been created by nbv. SHA-1: ecc293ae57fe48db2843f59fec9a4454ab0f8bb7 Detailed log of new commits: Author: nbv Date: Thu Nov 30 13:44:48 2017 +0300     0028833: Unstable result of intersection of the faces          Wrong distance computation in case of Approx_ChordLength approximation type has been corrected. git (administrator) 2017-12-01 10:55 Branch CR28833 has been deleted by nbv. SHA-1: ecc293ae57fe48db2843f59fec9a4454ab0f8bb7 nbv (developer) 2017-12-01 14:52 After the fix for issue #29359, the intersection result is following      Debian 7 64bit: bopcurves f1 f2 -2d # Tolerance Reached=1.9424317963481932e-06 # 7 curve(s) found. bopcurves f2 f1 -2d # Tolerance Reached=3.4328334306385459e-06 # 7 curve(s) found.      Windows, VC12, 64 bit: bopcurves f1 f2 -2d # Tolerance Reached=4.8853446536539142e-006 # 7 curve(s) found. bopcurves f2 f1 -2d # Tolerance Reached=1.1061046409178104e-006 # 7 curve(s) found. nbv (developer) 2017-12-01 14:54 Dear Eugeny, Please make conclusion about stability of this result. emv (developer) 2017-12-01 15:18 It is necessary to perform very careful analysis of these results before making such conclusion. But, since the results of Boolean SECTION operation on these faces is different on Windows and Linux, I think it is necessary to further improve the stability of intersection algorithm. nbv (developer) 2017-12-01 15:20 edited on: 2017-12-01 15:22 After discussion, this bug has been decided to keep in "open"-status until children bugs on Boolean operation (#29126, #29179 and #29180) will be fixed (they are not fixed by the patch #29359). All problems with intersector (if they still exists) must be automatically related to this issue. nbv (developer) 2017-12-04 17:50 Result of intersection with start points (after the fix #29359):      Linux: bopcurves a_1_1 a_2_1 -2d -p +1.57079632680779823772 -1260.00000000000000000000 +1.57079632680779823772 -914.00000000000000000000 -p +4.71238898039756382019 -1978.00000000000000000000 +4.71238898039756382019 -196.00000000000000000000 # Tolerance Reached=3.4190183427392574e-06 # 6 curve(s) found. bopcurves a_2_1 a_1_1 -2d -p +4.71238898039756382019 -196.00000000000000000000 +4.71238898039756382019 -1978.00000000000000000000 -p +1.57079632680779823772 -914.00000000000000000000 +1.57079632680779823772 -1260.00000000000000000000 # Tolerance Reached=1.7251058336056498e-06 # 6 curve(s) found.      Windows: bopcurves a_1_1 a_2_1 -2d -p +1.57079632680779820000 -1260.00000000000000000000 +1.57079632680779820000 -914.00000000000000000000 -p +4.71238900762224590000 -1978.00000000000000000000 +4.71238900762224590000 -196.00000000000011000000 # Tolerance Reached=8.7721154144228939e-005 # 6 curve(s) found. bopcurves a_2_1 a_1_1 -2d -p +4.71238900762224590000 -196.00000000000011000000 +4.71238900762224590000 -1978.00000000000000000000 -p +1.57079632680779820000 -914.00000000000000000000 +1.57079632680779820000 -1260.00000000000000000000 # Tolerance Reached=1.3952065448782561e-006 # 6 curve(s) found. --------------------------- I.e. the intersection result on Linux is much more resistant to reversing of arguments than on Windows. Nevertheless, the result of Boolean operation (section, cut) on Windows is much more stable than on Linux (see issue #29179). nbv (developer) 2018-02-19 11:58 Steps To Reproduce have been updated according to the situation on IR-2018-02-16.