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0021413Open CASCADE[OCCT] OCCT:Modeling Algorithmspublic2009-10-15 10:352017-06-30 12:03
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bugs modalg_7 bug21413
0021413: Pipe fails - very sensitive to spine parameterization
1. Uncompress enclosed pipe-spine.zip. It contains two equal spines, only
differing in precision used when saving in the file (.ok used default 5 or 6
digits, .err - 17)
2. Use DRAWEXE:
Draw> tuya res.err dc1.err 1
Draw> tuya res.ok dc1.ok 1

In OK case the resulting B-Spline is a good pipe surface (Vdeg=5, Vknots=31)
while in ERR case there is some failure (Vdeg=11, Vknots=285). Failure is closer
to the end of the spine (extra twisting resulting in degree increase, etc).
Spine knots have dense distribution closer to the start - this likely
contributes to the failure. However sensitivity seems to high when default
tolerance of pipe algorithm is 1e-04 and knots and poles differ only in <1e-6 scale.

Additional post:

After some investigations I noticed that the issue is rather (or only?) in poles
- if to reduce precision (e.g. to modify *.err file leaving only 7 digits in
every pole coordinate) the algorithm works fine. So it seems like some precision
non-robustness.
I could add some work-around into my code to round up each coordinate to 7
digits on the fly but that would be the least I'd like to do. Ugly hack slowing
down the code, to say the least ...
No tags attached.
zip pipe-spines.zip (43,841) 2009-10-15 10:35
https://tracker.dev.opencascade.org/
Issue History
2011-08-02 11:31bugmasterCategoryOCCT:MOA => OCCT:Modeling Algorithms
2017-06-28 18:03gitNote Added: 0067782
2017-06-28 18:04apvAssigned Tobugmaster => apv
2017-06-28 18:04apvStatusnew => feedback
2017-06-28 18:05apvNote Added: 0067783
2017-06-28 18:05apvAssigned Toapv => bugmaster
2017-06-28 18:05apvStatusfeedback => tested
2017-06-28 18:05apvTest case number => bugs modalg_7 bug21413
2017-06-28 18:05apvFixed in VersionEMPTY =>
2017-06-28 18:05apvDescription Updatedbug_revision_view_page.php?rev_id=16995#r16995
2017-06-30 12:03apvAssigned Tobugmaster => msv
2017-06-30 12:03apvStatustested => assigned

Notes
(0067782)
git   
2017-06-28 18:03   
Branch CR21413 has been created by apv.

SHA-1: f897957d0e8f6f8bec5a14098eaba3fde11e00ab


Detailed log of new commits:

Author: apv
Date: Wed Jun 28 18:03:25 2017 +0300

    0021413: Pipe fails - very sensitive to spine parameterization
    
    # Test case creation
(0067783)
apv   
2017-06-28 18:05   
Dear BugMaster,

Please integrate branch CR21413 into the occt git-repository master.

After integration issue status should be changed to assigned. Responsible person is msv.