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IDProjectCategoryView StatusDate SubmittedLast Update
0032557Community[OCCT] OCCT:Modeling Algorithmspublic2021-09-02 18:082021-09-02 18:28
Reporterlrineau 
Assigned Tomsv 
PrioritynormalSeveritymajor 
StatusnewResolutionopen 
PlatformLinuxOSDebian 6.0OS Version64 bit
Product Version[OCCT] 7.5.0 
Target VersionFixed in Version 
Summary0032557: Use of BRepBuilderAPI_NurbsConvert create 2d p-curves with errors
DescriptionWith the given STEP file `abc_0_31-mod.step` given in the attached zip file, the code `debug_issue.cpp` (also in the zip file) shows that the conversion to NURBS using `BRepBuilderAPI_NurbsConvert` create an incorrect wire, with 2d p-curve accumulating so much imprecision that the end points of the loop of p-curve in the wire no longer coincide.

Given the data set, the incriminated wire the one of the third face. I will attach screenshots...

The attached .cpp file loops on the edges of the wire, and displays the maximal distance between two endpoints (of p-curves) that should coincide. That process is run before and after the conversion to NURBS.
TagsNo tags attached.
Test case number
Attached Fileszip file icon debug_issue.zip (15,645 bytes) 2021-09-02 18:08
png file icon abc_31_third_face.png (43,187 bytes) 2021-09-02 18:08
png file icon wire.png (4,643 bytes) 2021-09-02 18:12
png file icon wire-nurbs.png (4,573 bytes) 2021-09-02 18:12
png file icon wire-nurbs-zoom.png (1,699 bytes) 2021-09-02 18:12

- Relationships

-  Notes
(0103686)
lrineau (reporter)
2021-09-02 18:14

I have upload a general view of the STEP face that has the incorrect wire (after the conversion to NURBS).

I have also uploaded a drawing of the wire, in the 2d parametric space, before and after the conversion to NURBS, as well as a zoom on the problematic zone.
(0103688)
lrineau (reporter)
2021-09-02 18:18

This bug occurs with OCCT version 7.5.0 (as shipped by Linux Fedora 34), and with the master branch of OCCT (commit dated Sun Jun 27 20:13:49 2021 +0300).

The bug was not present in OCCT version 7.4.0. That version 7.4.0 was ship in Linux Fedora 32, and I recompiled it locally to check again, just before the submission of this issue.

- Issue History
Date Modified Username Field Change
2021-09-02 18:08 lrineau New Issue
2021-09-02 18:08 lrineau Assigned To => msv
2021-09-02 18:08 lrineau File Added: debug_issue.zip
2021-09-02 18:08 lrineau File Added: abc_31_third_face.png
2021-09-02 18:12 lrineau File Added: wire.png
2021-09-02 18:12 lrineau File Added: wire-nurbs.png
2021-09-02 18:12 lrineau File Added: wire-nurbs-zoom.png
2021-09-02 18:14 lrineau Note Added: 0103686
2021-09-02 18:18 lrineau Note Added: 0103688
2021-09-02 18:26 kgv Product Version 7.5.3 => 7.5.0
2021-09-02 18:28 kgv Relationship added related to 0031242


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