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0032462Community[OCCT] OCCT:Meshpublic2021-06-27 01:342021-06-29 11:42
Windows 10Windows 10Windows 10
[OCCT] 7.4.0 
[OCCT] 7.6.0* 
0032462: Mesh - missing face issue, bad surface and bad volume [Regression compared to OCCT 7.3.0]
Hello dear community,

I'm facing an issue with the kernel of OCC.

To illustrate my issue I'm using CAD Assistant in the snapshots, but same regression could be observed with FreeCAD, PythonOCC...

If you open the attached STEP file in two version of CAD Assistant, in the more recent version, one face is missing, and then on this part volume and surface computation are KO.

cad_assistant_1.5.0_2020-12-28_win64 : version used for KO snapshot
cad_assistant_1.2_2018-10-30_win64 : version used for OK snapshot.

Do you have an idea on how to treat this part with the last versions of the kernel?

Healing of the step file?

Bug in the kernel?

Thanks for your attention,

Best regards

Guillaume STAMM
restore vol_731dev.brep b
#testreadstep volume_ko.stp b
tclean b
checkshape b b

incmesh b 1.0

vinit View1
vdisplay -dispMode 1 b

# KO
> -- The Shape b looks OK
> Meshing statuses: SelfIntersectingWire Failure

No tags attached.
related to 0025061new oan Open CASCADE BRepMesh should skip internal wires with self intersections to produce mesh for the shape anyway 
related to 0024084assigned oan Open CASCADE Additional tool for resolving 2d loops on discretized wires should be implemented in BRepMesh 
child of 0026106closed bugmaster Open CASCADE BRepMesh - revision of data model 
zip issue 3d and (369,257) 2021-06-27 01:34
? vol_731dev.brep (566,317) 2021-06-28 15:13
Issue History
2021-06-27 01:34gstammNew Issue
2021-06-27 01:34gstammAssigned To => abv
2021-06-27 01:34gstammFile Added: issue 3d and
2021-06-28 15:13kgvFile Added: vol_731dev.brep
2021-06-28 15:19kgvNote Added: 0102119
2021-06-28 15:19kgvProduct Version7.5.1 => 7.4.0
2021-06-28 15:19kgvTarget Version => 7.6.0*
2021-06-28 15:19kgvSteps to Reproduce Updatedbug_revision_view_page.php?rev_id=25414#r25414
2021-06-28 15:20kgvAssigned Toabv => oan
2021-06-28 15:20kgvSeveritymajor => minor
2021-06-28 15:20kgvCategoryOCCT:Foundation Classes => OCCT:Mesh
2021-06-28 15:20kgvSummaryRegression on OCC: missing face issue, bad surface and bad volume => Mesh - missing face issue, bad surface and bad volume [Regression compared to OCCT 7.3.0]
2021-06-28 15:22kgvRelationship addedchild of 0026106
2021-06-28 15:22kgvRelationship addedrelated to 0025061
2021-06-29 11:42oanRelationship addedrelated to 0024084

2021-06-28 15:19   
> in the more recent version, one face is missing
Face is not missing, it is still there, but triangulation algorithm fails on it due to wire self-intersection error.

This is either a problem in Face definition, or BRepMesh classifier issue.