View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0025793 | Community | OCCT:Modeling Algorithms | public | 2015-02-04 14:05 | 2015-02-06 11:14 |
| Reporter | Timo | Assigned To | bugmaster | ||
| Priority | normal | Severity | minor | ||
| Status | closed | Resolution | no change required | ||
| Platform | win32 vc10 | ||||
| Product Version | 6.8.0 | ||||
| Target Version | 6.9.0 | ||||
| Summary | 0025793: BRepAlgoAPI_Section fails when calculating the section of a face and a shell | ||||
| Description | When calculating the intersection of the appended face and a trimmed shell, BRepAlgoAPI_Section fails INDEPENDENT on the order of the arguments. The related issue 0025792 contains only the problematic face of the shell and is untrimmed. Then the correctness of the result depends on the order of the arguments. checkshape and bopcheck do not indicate any problems. However, the problematic face is strongly bent. | ||||
| Steps To Reproduce | restore Turbine_VTG_Shell.brep t explode t bop t_1 t_2 bopsection r whatis r explode r => r contains 3 edges but should have 4 edges FALSE! bop t_2 t_1 bopsection r whatis r explode r => r contains 3 edges but should have 4 edges FALSE! | ||||
| Tags | No tags attached. | ||||
| Test case number | |||||
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Turbine_VTG_Shell.brep (435,682 bytes) |
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Answer of Sergey Zaritchny: Actually, here we have faced with improper designed surface. Due to twisted poles in interior of the surface it has self-intersection. See the snapshot below. It shows the zoomed-in portion of the V-iso line of the surface with parameter 0.9545. You can see here a definite loop in the 'iso' line. In addition the surface has oscillations near the bend. The snapshot below shows zoomed-in bending portion of the surface boundary (V-iso line with parameter 1). The intersection algorithm cannot give a good stable result with such input geometry. It is needed to redesign this surface so that it did not contain at least self-intersections, and at most was as smooth as possible, especially in the place where intersection with another body occurs. Additional note. A surface should be C1-continuous. So, if you need to model a sharp bend in geometry of a body it must be modeled with an edge shared by two faces. Unfortunately it is not possible to identify such cases by BRepCheck_Analyzer as each become apparent only inside Intersection algorithm. Conclusion. Improper designed surface. |
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self-intersection.png (9,353 bytes) |
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oscillations.png (10,917 bytes) |
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Because the input surface is problematic, I close this issue. |
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Dear bugmaster, please close this bug. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2015-02-04 14:05 | Timo | New Issue | |
| 2015-02-04 14:05 | Timo | Assigned To | => msv |
| 2015-02-04 14:05 | Timo | File Added: Turbine_VTG_Shell.brep | |
| 2015-02-04 14:05 | Timo | Issue generated from: 0025792 | |
| 2015-02-04 14:05 | Timo | Relationship added | related to 0025792 |
| 2015-02-04 15:07 | Timo | Description Updated | |
| 2015-02-05 16:01 | Timo | Note Added: 0037129 | |
| 2015-02-05 16:01 | Timo | File Added: self-intersection.png | |
| 2015-02-05 16:01 | Timo | File Added: oscillations.png | |
| 2015-02-05 16:17 | Timo | Note Added: 0037132 | |
| 2015-02-05 16:17 | Timo | Status | new => resolved |
| 2015-02-05 17:30 |
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Note Added: 0037141 | |
| 2015-02-05 17:30 |
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Assigned To | msv => bugmaster |
| 2015-02-05 17:30 |
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Status | resolved => reviewed |
| 2015-02-05 18:24 |
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Status | reviewed => feedback |
| 2015-02-06 11:14 | bugmaster | Status | feedback => closed |
| 2015-02-06 11:14 | bugmaster | Resolution | open => no change required |
