View Issue Details
|ID||Project||Category||View Status||Date Submitted||Last Update|
|0025586||Community||OCCT:Mesh||public||2014-12-10 13:11||2023-01-17 02:34|
|Reporter||Istvan Csanady||Assigned To||bugmaster|
|Status||closed||Resolution||no change required|
|Summary||0025586: Mesh - Poor mesh quality, or failure of meshing for closed extruded surfaces with holes|
|Description||When I add a hole to a closed extruded face, BRepMesh will fail to triangulate it, or will make a wrong mesh from the face (half of the mesh is missing). See the attached example files. (ShapeFix_Shape was performed in all the faces.) The meshing fails, because BRepMesh_WireChecker::collectDiscretizedWires returns false, because it thinks that the outer wire is open.|
|Steps To Reproduce||Load the attached files to DRAWEXE. They will not be visible in shaded rendering mode.|
|Tags||No tags attached.|
|Test case number||bugs mesh bug25586_1, bug25586_2, bug25586_3|
meshing_failures.zip (9,938 bytes)
IMG_0090.PNG (511,993 bytes)
||I have attached an image of the result mesh. It should be a cylinder, with a hole.|
IMG_0091.PNG (456,581 bytes)
|Oleg, please look at this problem when you have time.|
tmp.stp (13,052 bytes)
I have tested this with the current main branch, and the problem still exists. I tested it with 3rd party data (just to be sure, that the problem is not in my code), and I successfully reproduced it. See the attached STEP file.
It seems, that not only extruded faces are involved, but all faces that are closed in one direction.
Steps to reproduce:
ReadStep d tmp.stp
XGetOneShape shape d
||I have attached a wrong stp file, but the bug can be reproduced with the attached brep files.|
Problem described in issue is reproduced on current state of OCCT.
circle_extrusion_2d.png (2,164 bytes)
Attached shapes contain narrow notched tail in parametric space which cannot be processed by triangulator correctly and lead to degenerative triangles that are forbidden by BRepMesh (circle_extrusion_2d.png).
I consider it as inconsistency of the models which should be fixed by shape healing tool first.
Could you please check shapes and move this issue to shape healing category or make a decision about further plans?
bopargcheck reports inconsistencies, e.g.:
bopargcheck a #F
Made faulty shape: s1si_1
Faulties for FIRST shape found : 1
Shapes are not suppotrted by BOP: NO
Self-Intersections : YES Cases(1) Total shapes(2)
Check for SI has been aborted : NO
Too small edges : NO
Bad faces : NO
Too close vertices : DISABLED
Too close edges : DISABLED
Shapes with Continuity C0 : NO
Invalid Curve on Surface : NO
Faulties for SECOND shape found : 0
please have a look at the screenshot of 2d view and description to it:
BRepMesh is unable to produce correct mesh for shapes with such degeneracy in parametric space and existing result is the most appropriate for it.
I suggest to accept this case, obviously the result of some BOP operation upon some tricky design, as invalid and consider possibility to heal it using fixshape due to the absence of initial data producing such geometry (sure it would be better to analyze the initial sequence of actions that led to the reported issue).
I also suggest to move this issue to Shape Healing category as BRepMesh has nothing to deal here with.
I agree. I consider this model invalid. BRepMesh makes all its best to produce some triangles on it.
I think we should close this issue as not a bug.
||Closed. Not a bug.|
|2014-12-10 13:11||Istvan Csanady||New Issue|
|2014-12-10 13:11||Istvan Csanady||Assigned To||=> msv|
|2014-12-10 13:11||Istvan Csanady||File Added: meshing_failures.zip|
|2014-12-11 10:19||Istvan Csanady||File Added: IMG_0090.PNG|
|2014-12-11 10:19||Istvan Csanady||Note Added: 0035300|
|2014-12-11 10:22||Istvan Csanady||File Added: IMG_0091.PNG|
||Assigned To||msv => oan|
||Note Added: 0035302|
|2014-12-15 09:29||Istvan Csanady||File Added: tmp.stp|
|2014-12-15 09:35||Istvan Csanady||Note Added: 0035399|
|2014-12-15 10:21||Istvan Csanady||Note Added: 0035400|
||Target Version||6.9.0 => 7.1.0|
||Category||OCCT:Modeling Algorithms => OCCT:Mesh|
|2016-04-05 14:31||oan||Relationship added||related to 0024084|
|2016-10-26 18:11||oan||Target Version||7.1.0 => 7.2.0|
|2017-07-20 12:43||oan||Target Version||7.2.0 => 7.3.0|
||Test case number||=> bugs mesh bug25586_1, bug25586_2, bug25586_3|
||Note Added: 0069125|
||Target Version||7.3.0 => 7.4.0|
|2019-09-04 17:55||kgv||Summary||Poor mesh quality, or failure of meshing for closed extruded surfaces with holes => Mesh - Poor mesh quality, or failure of meshing for closed extruded surfaces with holes|
|2019-09-06 18:12||oan||File Added: circle_extrusion_2d.png|
|2019-09-06 18:22||oan||Note Added: 0086908|
|2019-09-06 18:22||oan||Assigned To||oan => abv|
|2019-09-06 18:22||oan||Status||new => feedback|
|2019-09-06 18:26||oan||Note Added: 0086909|
||Target Version||7.4.0 => 7.5.0|
|2020-08-28 15:47||oan||Target Version||7.5.0 => Unscheduled|
|2022-11-01 18:36||oan||Assigned To||abv => msv|
|2022-11-01 18:47||oan||Note Added: 0111827|
|2022-11-01 18:48||oan||Note Edited: 0111827|
|2022-11-01 18:52||oan||Note Edited: 0111827|
||Note Added: 0111829|
||Assigned To||msv => bugmaster|
|2023-01-17 02:34||vglukhik||Status||feedback => closed|
|2023-01-17 02:34||vglukhik||Resolution||open => no change required|
|2023-01-17 02:34||vglukhik||Note Added: 0112843|