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IDProjectCategoryView StatusLast Update
0031672CommunityOCCT:Data Exchangepublic2024-03-08 12:32
ReporterAlexandru Assigned Todpasukhi  
PrioritynormalSeveritymajor 
Status newResolutionopen 
OSWindows 
Product Version7.4.0 
Summary0031672: Data Exchange, STEP reader - Surface wrongly recognized as degenerate torus
DescriptionIn the attached geometry, one of the surfaces is recognized as degenerated torus. The thing is: There is no torus in this simple geometry. See file attached.
TagsNo tags attached.
Test case number

Attached Files

  • 37.stp (3,959 bytes)
  • temp.jpg (8,301 bytes)
  • section_view_37step.png (86,881 bytes)
  • fullview37step.png (111,485 bytes)

Relationships

related to 0033618 newika STEP-import of DEGENERATE_TOROIDAL_SURFACE can be misinterpreted. 

Activities

Alexandru

2020-07-17 19:44

reporter  

37.stp (3,959 bytes)

kgv

2020-07-24 12:38

developer   ~0093284

I suppose that torus surface is created from the following item in STEP file:
#61=DEGENERATE_TOROIDAL_SURFACE('',#42974,0.273874678843767,9.99999999999133,.F.);

Alexandru

2020-07-24 12:42

reporter   ~0093285

Forgot to say: I can load the STEP without any problems in SolidWorks.

kgv

2020-07-24 13:04

developer   ~0093289

> Forgot to say: I can load the STEP without any problems in SolidWorks.
If it looks different in SolidWorks - it would be helpful also attaching screenshots.

Alexandru

2020-07-24 15:04

reporter  

temp.jpg (8,301 bytes)

Alexandru

2020-07-24 15:05

reporter   ~0093291

I uploaded a screenshot of the actual geometry as section view.

Alexandru

2020-07-24 15:09

reporter   ~0093292

The volume a rotational symmetry axis, that's why I choosed to show it as a section view

dpasukhi

2021-02-28 23:43

administrator   ~0099230

Last edited: 2021-02-28 23:44

Solution elaboration & Testing

1) Updating of transfer STEP entity to geom not fixed the incorrect visualization. ( An example implementation is taken from the Xt format )
- The new resulting shape is a ylinder with rounded base surfaces.
2)SolidWork create a unexpected cutted form.
- The created toroidal self-intersection surface is practically a sphere and does not lead to the formation of the shape obtained in SolidWork.

ebknudsen

2024-03-08 11:15

developer   ~0115277

Just to confirm - I tried importing this same step-file in onShape, and got it interpreted as the expected result, i.e. a cylinder with rounded ends. See attached screenshot.
section_view_37step.png (86,881 bytes)
fullview37step.png (111,485 bytes)

Alexandru

2024-03-08 11:56

reporter   ~0115279

So OnShape and SolidWorks can interpret the geometry correctly.
I suppose, OnShape does not make use of the OCC parser, right?
So the conclusion would be, that there is a bug in OCC (still).

ebknudsen

2024-03-08 12:22

developer   ~0115280

With the caveat that I have no way of knowing what library, if any, is used for step-interpretation in onShape - that would be the conclusion yes.
I recently raised a new issue (see related 0033618) before being aware of this one.

Alexandru

2024-03-08 12:32

reporter   ~0115281

Very happy to hear, that I'm not the only one with this issue.
I allow myself to link to your new issue: https://tracker.dev.opencascade.org/view.php?id=0033618

Issue History

Date Modified Username Field Change
2020-07-17 19:44 Alexandru New Issue
2020-07-17 19:44 Alexandru Assigned To => gka
2020-07-17 19:44 Alexandru File Added: 37.stp
2020-07-24 12:36 kgv Product Version => 7.4.0
2020-07-24 12:36 kgv Summary Surface wrongly recognized as degenerate torus => Data Exchange, STEP reader - Surface wrongly recognized as degenerate torus
2020-07-24 12:38 kgv Note Added: 0093284
2020-07-24 12:42 Alexandru Note Added: 0093285
2020-07-24 13:04 kgv Note Added: 0093289
2020-07-24 15:04 Alexandru File Added: temp.jpg
2020-07-24 15:05 Alexandru Note Added: 0093291
2020-07-24 15:09 Alexandru Note Added: 0093292
2020-08-26 12:10 gka Assigned To gka => dpasukhi
2021-02-28 23:43 dpasukhi Note Added: 0099230
2021-02-28 23:44 dpasukhi Note Edited: 0099230
2024-03-07 16:22 dpasukhi Relationship added related to 0033618
2024-03-08 11:15 ebknudsen Note Added: 0115277
2024-03-08 11:15 ebknudsen File Added: section_view_37step.png
2024-03-08 11:15 ebknudsen File Added: fullview37step.png
2024-03-08 11:56 Alexandru Note Added: 0115279
2024-03-08 12:22 ebknudsen Note Added: 0115280
2024-03-08 12:32 Alexandru Note Added: 0115281