0030466: Problems removing non-isolated holes - MantisBT

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ID

Project

Category

View Status

Date Submitted

Last Update

0030466

Community

[OCCT] OCCT:Modeling Algorithms

public

2019-01-31 17:34

2019-02-01 10:15

Reporter

emei

Assigned To

msv

Priority

normal

Severity

minor

Status

new

Resolution

open

Platform

Windows

OS

VC++ 2015

OS Version

64 bit

Product Version

[OCCT] 7.3.0

Target Version

Fixed in Version

Summary

0030466: Problems removing non-isolated holes

Description

Noticed when working on CADProcessor: concerns BRepAlgoAPI_Defeaturing

Problem when trying to remove a hole which is lying on more than 1 support face (the hole is at the intersection of multiple faces).

The algorithm fails to remove the hole.

Steps To Reproduce

restore 2019-01-15_Intrados-HolesRemoved.brep a

explode a F
removefeatures result a a_19 a_20 a_25 a_26

Additional information
and documentation updates

From a preliminary study, the input looks OK (the feature faces and adjacent faces numbers are correct).
But the solid is not recreated properly, from BOPAlgo_MakerVolume::PerformInternal1, after BuildSolids call, only the bounding box is recreated, which leaves us with no result shape at the end.

Tags

No tags attached.

Test case number

2019-01-15_Intrados-HolesRemoved.brep (910,293 bytes) 2019-01-31 17:34

bug30466_extfaces.brep (166,251 bytes) 2019-02-01 10:15

Relationships

(0081983)
emv (developer)
2019-02-01 10:15

The input shapes has a huge tolerance relatively the model size. Try the command 'tolsphere' in draw to see the tolerances of vertices:

tolsphere a

It is not safe to pass such arguments into the modeling operations.

But even after reducing the tolerances of the shape with the following commands:

settolerance a 1.e-7
fixshape a a

the algorithms fails to remove the hole.

It seems the reason is the huge tolerance obtained by the Face/Face intersection algorithm when intersecting the extended faces filling the hole. These tolerances do not allow producing the correct volume.
Here is the script to see these intersection tolerances:

restore bug30466_extfaces.brep c
explode c f

bopcurves c_2 c_3 -2d
# Tolerance Reached=0.53837672555709137

Issue History
Date Modified	Username	Field	Change
2019-01-31 17:34	emei	New Issue
2019-01-31 17:34	emei	Assigned To	=> msv
2019-01-31 17:34	emei	File Added: 2019-01-15_Intrados-HolesRemoved.brep
2019-02-01 10:15	emv	Note Added: 0081983
2019-02-01 10:15	emv	File Added: bug30466_extfaces.brep

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