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IDProjectCategoryView StatusLast Update
0033234CommunityOCCT:Shape Healingpublic2024-03-01 14:56
Reporterbogdan_138692 Assigned To 
PrioritynormalSeveritymajor 
Status assignedResolutionopen 
PlatformWindowsOSVC++ 2019 
Product Version7.6.3 
Target VersionUnscheduled 
Summary0033234: BRepMesh_IncrementalMesh does not fully triangulate some surfaces
DescriptionWhen meshing with BRepMesh_IncrementalMesh some surfaces are not triangulated or partially triangulated.
The results are better when using IMeshTools_MeshAlgoType_Delabella, but there are still some holes.
The issue is present in OCCT v7.6.3 and 7.7.0. Screenshots are made with linear deflection = 1, relative = false, angular deflection = 0.1.
Its a regression as there is no issue in OCCT v7.2.0.

Model:
https://drive.google.com/file/d/1erN0jbejBQVS-bEliuy5jcZYI27zygFJ/view?usp=share_link
TagsNo tags attached.
Test case number

Attached Files

  • image.png (393,875 bytes)
  • delabella.png (133,680 bytes)
  • Swirler.png (75,416 bytes)
  • Swirler.zip.001 (2,097,152 bytes)
  • Swirler.zip.002 (2,097,152 bytes)
  • Swirler.zip.003 (2,097,152 bytes)
  • Swirler.zip.004 (2,097,152 bytes)
  • Swirler.zip.005 (1,229,918 bytes)

Relationships

duplicate of 0033233 new BRepMesh_IncrementalMesh does not fully triangulate some surfaces 

Activities

bogdan_138692

2022-11-29 22:23

reporter   ~0112408

image.png (393,875 bytes)
delabella.png (133,680 bytes)

oan

2022-11-30 22:17

developer   ~0112434

Last edited: 2022-11-30 22:19

Hello @bogdan_138692,

the shape contains some issues that cause triangulation look bad.
checkshape reports the following problems:
On Shape faulty_1 :
BRepCheck_SelfIntersectingWire
On Shape faulty_2 :
BRepCheck_UnorientableShape
Shape faulty_1  on shape faulty_2 :
BRepCheck_SelfIntersectingWire
On Shape faulty_3 :
BRepCheck_SelfIntersectingWire
On Shape faulty_4 :
BRepCheck_UnorientableShape
Shape faulty_3  on shape faulty_4 :
BRepCheck_SelfIntersectingWire

Faulty shapes in variables faulty_1 to faulty_4

Note that the issues reported either by checkshape or bopargcheck notify user about general problems that could cause further degeneracy in any algorithm, BRepMesh is not an exception.
All these problems say that design in imperfect and should be fixed either manually, or using fixshape.

Using fixshape like this:
stepread Swirler.step a *
fixshape r a_1 +i

Gives the result pictured on the attached screenshot.
Despite of nice looking result, there are some problems anyway:

tricheck reports free nodes, which is practically thin holes along border of just some skipped nodes from initial discretization.

Moreover, checkshape also says about the same problems reported before healing procedure.

Like this, current issue is just a visual representation of hidden design problems existing in its parts and should be qualified as related to Shape Healing component.
Swirler.png (75,416 bytes)

oan

2022-11-30 22:24

developer   ~0112435

@bogdan_138692,

by the way, it seems that the shape is the result of some sweep operation or so.

It would be nice if you added the source shapes or script that are used to produce the problematic solid (the one you have already attached) in order to analyze the cause of the problems mentioned in the previous message.

oan

2022-11-30 22:30

developer   ~0112436

Swirler.zip.001 (2,097,152 bytes)

oan

2022-11-30 22:30

developer   ~0112437

Swirler.zip.002 (2,097,152 bytes)

oan

2022-11-30 22:30

developer   ~0112438

Swirler.zip.003 (2,097,152 bytes)

oan

2022-11-30 22:30

developer   ~0112439

Swirler.zip.004 (2,097,152 bytes)

oan

2022-11-30 22:30

developer   ~0112440

Swirler.zip.005 (1,229,918 bytes)

bogdan_138692

2022-12-01 19:52

reporter   ~0112457

The shape was generated in SolidWorks and exported to STEP.

Issue History

Date Modified Username Field Change
2022-11-29 22:21 bogdan_138692 New Issue
2022-11-29 22:21 bogdan_138692 Assigned To => oan
2022-11-29 22:23 bogdan_138692 Note Added: 0112408
2022-11-29 22:23 bogdan_138692 File Added: image.png
2022-11-29 22:23 bogdan_138692 File Added: delabella.png
2022-11-30 21:55 oan Relationship added duplicate of 0033233
2022-11-30 22:17 oan Note Added: 0112434
2022-11-30 22:17 oan File Added: Swirler.png
2022-11-30 22:18 oan Note Edited: 0112434
2022-11-30 22:19 oan Note Edited: 0112434
2022-11-30 22:24 oan Note Added: 0112435
2022-11-30 22:30 oan Note Added: 0112436
2022-11-30 22:30 oan File Added: Swirler.zip.001
2022-11-30 22:30 oan Note Added: 0112437
2022-11-30 22:30 oan File Added: Swirler.zip.002
2022-11-30 22:30 oan Note Added: 0112438
2022-11-30 22:30 oan File Added: Swirler.zip.003
2022-11-30 22:30 oan Note Added: 0112439
2022-11-30 22:30 oan File Added: Swirler.zip.004
2022-11-30 22:30 oan Note Added: 0112440
2022-11-30 22:30 oan File Added: Swirler.zip.005
2022-12-01 14:56 oan Assigned To oan => ika
2022-12-01 14:56 oan Category OCCT:Mesh => OCCT:Shape Healing
2022-12-01 19:52 bogdan_138692 Note Added: 0112457
2022-12-15 10:44 szy Status new => assigned
2023-09-29 18:07 ika Assigned To ika =>
2023-09-29 18:07 ika Target Version => Unscheduled