0031449: Mesh - BRepMesh works too long and produces many free nodes on a valid face

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0031449

Open CASCADE

[OCCT] OCCT:Mesh

public

2020-03-20 09:16

2020-08-28 15:43

Reporter

abv

Assigned To

oan

Priority

normal

Severity

minor

Status

new

Resolution

open

Platform

OS Version

Product Version

Target Version

[OCCT] 7.6.0*

Fixed in Version

Summary

0031449: Mesh - BRepMesh works too long and produces many free nodes on a valid face

Description

The shape analyzed in context of #31301 exhibits problems in meshing occuring after export of the original shape (initially imported from STEP) to STEP and importing back, in a case when parameter xstep.cascade.unit is set to meters during last import. The meshing takes enormous time (effectively hangs) and (when suceeds) produces a lot of free nodes.

Originally detected in CAD Assistant which just hangs and eats all available memory when reading the exported STEP file if unit settings are "M".

Steps To Reproduce

1. Full variant of original sequence in DRAW (hang or too long to wait for):

pload XDE AISV
ReadStep D [locate_data_file bug31301.stp]
WriteStep D bug31301_exported.stp
param xstep.cascade.unit M
ReadStep Q bug31301_exported.stp
XShow Q
----> WAIT (forever?)!

2. Simplified variant (prototype of test case) using single face (one that caused problems in #31301) already passed through all import - export steps:

pload MODELING MESH
restore [locate_data_file bug31301_face_loopback_M.brep] a
checkshape a
tolerance a

dchrono s restart
incmesh a 0.0001
dchrono s stop show
# meshing must be fraction of second, takes ~ 30 sec

tricheck a
# 6.000+ free nodes

3. Reproduction of the situation of CAD Assistant that eats ~ 30 GB of memory in ~ 3 min (on 6-core CPU):

pload MODELING
restore [locate_data_file bug31301_2_exported.brep] a
incmesh a 0.00039624 -a 20 -min 0.0001 -parallel

(the file is attached to #31301)

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No tags attached.

Test case number

Attached Files

bug31301_face_loopback_M.brep (24,500 bytes) 2020-03-20 09:16

free_nodes_axo.png (4,333 bytes) 2020-03-20 10:55

free_nodes_UV.png (2,096 bytes) 2020-03-20 10:56

Relationships

related to

0025287

closed

bugmaster

Community

BRepMesh_IncrementalMesh produces (way) out of tolerance mesh

Notes
(0091075) oan (developer) 2020-03-20 10:54 edited on: 2020-03-20 11:00	It is strange, but reported free nodes are all visually located out of face boundary (see attached screenshots). To be analysed.

Issue History
Date Modified	Username	Field	Change
2020-03-20 09:16	abv	New Issue
2020-03-20 09:16	abv	Assigned To	=> oan
2020-03-20 09:16	abv	File Added: bug31301_face_loopback_M.brep
2020-03-20 09:16	abv	Steps to Reproduce Updated	View Revisions
2020-03-20 09:16	abv	Relationship added	child of 0031301
2020-03-20 10:12	oan	Relationship added	related to 0025287
2020-03-20 10:44	abv	Steps to Reproduce Updated	View Revisions
2020-03-20 10:44	abv	File Added: bug31301_2_exported.brep
2020-03-20 10:47	abv	File Deleted: bug31301_2_exported.brep
2020-03-20 10:47	abv	Steps to Reproduce Updated	View Revisions
2020-03-20 10:54	oan	Note Added: 0091075
2020-03-20 10:55	oan	File Added: free_nodes_axo.png
2020-03-20 10:56	oan	File Added: free_nodes_UV.png
2020-03-20 11:00	oan	Note Edited: 0091075	View Revisions
2020-08-28 15:43	oan	Target Version	7.5.0 => 7.6.0*