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0028414Community[OCCT] OCCT:Data Exchangepublic2017-01-30 19:282019-09-04 15:36
[OCCT] 6.9.1 
[OCCT] 7.5.0* 
Not required
0028414: Step entity not correctly read.
We have identified an entity (STEP TOROIDAL_SURFACE) that is not correctly read (see the screen shots of IDA-Step and FreeCAD).
We have isolated the entity in a as small as possible Step file in order to help the correction.
Thank in advance for your help.
- Open the file in IDA-STEP and FreeCAD and see that in FreeCad, only the shape intersection seem to be displayed.
No tags attached.
related to 0029564new gka Community STEP Import and Export failure 
zip (507,140) 2017-01-30 19:28
? bug_tore.stp (15,501) 2018-04-28 12:56
png Capture d’écran 2018-05-01 à 16.32.27.png (49,193) 2018-05-01 17:33
png Capture d’écran 2018-05-01 à 16.32.54.png (84,779) 2018-05-01 17:34
Issue History
2017-01-30 19:28gdwNew Issue
2017-01-30 19:28gdwAssigned To => san
2017-01-30 19:28gdwFile Added:
2017-01-30 19:36sanAssigned Tosan => gka
2017-01-30 19:36sanCategoryPRODUCTS:Volume Rendering => OCCT:Data Exchange
2017-01-31 09:47abvNote Added: 0063235
2017-02-02 14:22abvRelationship addedrelated to 0025523
2017-08-30 14:57mkvTest case number => bugs step bug28414
2017-10-02 15:45apvTest case numberbugs step bug28414 => Not required
2018-01-02 12:25gdwNote Added: 0073218
2018-01-04 04:34eryarNote Added: 0073228
2018-04-28 12:56gdwFile Added: bug_tore.stp
2018-04-28 12:56gdwNote Added: 0075740
2018-05-01 17:33gdwFile Added: Capture d’écran 2018-05-01 à 16.32.27.png
2018-05-01 17:34gdwFile Added: Capture d’écran 2018-05-01 à 16.32.54.png
2018-05-01 17:39gdwNote Added: 0075755
2018-05-12 10:52gdwNote Added: 0075949
2018-05-18 08:16gdwNote Added: 0076020
2018-05-26 21:10abvTarget Version => 7.4.0
2018-05-26 21:10abvRelationship addedrelated to 0029564
2018-08-19 13:14gdwNote Added: 0078684
2019-09-04 15:36abvTarget Version7.4.0 => 7.5.0*

2017-01-31 09:47   
Among available STEP viewers:
- Autodesk A360 and GOM Inspect (based on Hoops by TechSoft3D), PTC Creo Elements show this face as almost full torus;
- OCCT, FreeCAD, RGK show it as small part;
- Rhino fails to open it;
- STEP NC shows broken shape.

Thus translation of toruses to and from STEP definitely deserves to be checked.
2018-01-02 12:25   
What is the status of this issue?
Thks in advance
2018-01-04 04:34   
Hi gdw,

I think this may have relationships with 0027722: [^]
2018-04-28 12:56   
The problem seems to be not related to the ellipse but preferably to the BSP subtraction.

In the file bug_tore, if
0000329 = ADVANCED_FACE( '', ( #749 ), #750, .T. );

is replaced by
0000329 = ADVANCED_FACE( '', ( ), #750, .T. );

the tore is read by occ; otherwise, only the cookie is read...

Hope this help
2018-05-01 17:39   

After investigations, the problem seems to come from the way the tore is cut by the wire in the ADVANCED_FACE: the part that should kept is 'outside' while occ keeps 'inside', as shown in the screenshots (the yellow one is correct while the gray one is what occ produces).
Currently I am trying to investigate in BrepMesh_FastDiscret.cxx that actually triangule the tore...
Help will infinitely appreciated!
2018-05-12 10:52   
More over, the problem seems to come when some B_SPLINE_CURVE_WITH_KNOTS are involved in the EdgeLoop of the ADVANCED_FACE; not sure that the problem is limited if the surface of the ADVANCED_FACE is a torus...
Feedback and help greatly appreciated!
2018-05-18 08:16   
We have temporarily fixed the problem by suppressing the edge part of the advanced face if the target form is a toroids and if the edges are made exclusively with knots surface. This inly a work around...
2018-08-19 13:14   
For more information, the problem comes from FACE_OUTER_BOUND...