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IDProjectCategoryView StatusLast Update
0031449Open CASCADEOCCT:Meshpublic2021-10-06 16:57
Reporterabv Assigned Tooan  
Status newResolutionopen 
Target Version7.7.0 
Summary0031449: Mesh - BRepMesh works too long and produces many free nodes on a valid face
DescriptionThe 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 Reproduce1. 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:

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):

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)
TagsNo tags attached.
Test case number

Attached Files

  • bug31301_face_loopback_M.brep (24,500 bytes)
  • free_nodes_axo.png (4,333 bytes)
  • free_nodes_UV.png (2,096 bytes)


related to 0025287 closedbugmaster Community BRepMesh_IncrementalMesh produces (way) out of tolerance mesh 



2020-03-20 09:16


bug31301_face_loopback_M.brep (24,500 bytes)


2020-03-20 10:54

developer   ~0091075

Last edited: 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.


2020-03-20 10:55


free_nodes_axo.png (4,333 bytes)


2020-03-20 10:56


free_nodes_UV.png (2,096 bytes)

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
2020-03-20 10:12 oan Relationship added related to 0025287
2020-03-20 10:44 abv Steps to Reproduce Updated
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
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
2020-08-28 15:43 oan Target Version 7.5.0 => 7.6.0
2021-10-06 16:57 szy Target Version 7.6.0 => 7.7.0