FreeCADView Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0002639 | FreeCAD | Bug | public | 2016-07-24 21:47 | 2016-08-07 16:25 |
| Reporter | vokars | Assigned To | |||
| Priority | high | Severity | major | Reproducibility | always |
| Status | closed | Resolution | unable to reproduce | ||
| Platform | Windows | OS | Windows Professional | OS Version | 7 SP1 32 Bit |
| Product Version | 0.16 | ||||
| Fixed in Version | 0.17 | ||||
| Summary | 0002639: STL Export not manifold | ||||
| Description | I am the typical average user who does what "everybody" does: Downloading files from thingiverse that never fit exactly my needs and need smaller changes. And exactly that makes problems with freeCAD: 1. Import stl 2. Create shape from mesh 3. Refine shape 4. Convert to solid 5. Even direct export to stl without any change creates an error in Repetier Host: Object not manifold. Analyzing the stl-Export with FreeCAD (Mesh-Workbench) finds many errors but the repair makes it usually only worse. Searching in forums only delvers complicated special solutions. I also get error messages with some subsequent boolean operations that only occur with modified stl-imports and never with models created from scratch. | ||||
| Steps To Reproduce | http://www.thingiverse.com/thing:797733/#collections And now the good news: Autodesk Mesh Mixer does the automatic repair of the FreeCAD stl-Export that can be used in Repetier Host. | ||||
| Additional Information | The Mesh Mixer workaround works but to figure that out was a lot of work and probably most users do not know that. I assume that FreeCAD lost many many users due to this problem. Conclusion - STL to Shape conversion doesn't work properly - Mesh-repair doesn't work properly: Not when repaired the original import or when repaired the reimported stl-export. - Working with stl-Import unstable in general especially subsequent boolean operations - The problem can be solved: Autodesk already did it. - It is a problem of the masses: Non-Developer average 3D-Printer users. | ||||
| Tags | No tags attached. | ||||
| FreeCAD Information | |||||
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To clarify: The stl IMPORT does NOT make problems in Repetier Host: It is manifold. But the Export of FreeCAD is NOT manifold. FreeCAD corrupts the STL. This Bug is not concerned with bad STL-Imports only with bad STL Exports. |
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It would be good to mention at least a single file for which the export apparently does something wrong. From the link above there are four stls glcd_tester_lcr_t4_bottom.stl, glcd_tester_lcr_t4_extra_bottom.stl, glcd_tester_lcr_t4_extra_top.stl and glcd_tester_lcr_t4_top.stl. When importing and exporting them with FreeCAD and then checking all 8 eight files with MeshLab then it reports exactly the same errors for old and new files. Especially for the original version of glcd_tester_lcr_t4_top.stl MeshLab finds the same non-manifold edge as FreeCAD. > - STL to Shape conversion doesn't work properly > - Working with stl-Import unstable in general especially subsequent boolean operations If you read the forum posts you would know that in general this doesn't work. The point is when creating an STL from a shape all the mathematical information about curved areas is lost because they are only approximated by a set of triangles. Reading in the STL and converting it to a shape doesn't bring back the lost information. Therefore you had to apply reverse engineering methods. So, any subsequent changes on model created this way will never work properly and you shouldn't blame FreeCAD for this. > - Mesh-repair doesn't work properly: Not when repaired the original import or when repaired the reimported stl-export. These function were never supposed to work for very ill-formed triangles as from the above stls. Their main focus is to work with triangles created from optical scanners. |
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Thank you for your answer: 1. "It would be good to mention at least a single file for which the export apparently does something wrong." glcd_tester_lcr_t4_extra_top.stl 2. "When importing and exporting them with FreeCAD and then checking all 8 eight files with MeshLab then it reports exactly the same errors for old and new files. Especially for the original version of glcd_tester_lcr_t4_top.stl MeshLab finds the same non-manifold edge as FreeCAD." I described a procedure in this bug report that uses Repetier Host. Did you check it to reproduce the reported bug? Repetier Host is not just any special software: It is the standard in reprap 3D printing and therefore software of the "masses" and it is therefore important that a CAD export works with it in a typical workflow. And it definitely does not. 3. "If you read the forum posts you would know that in general this doesn't work." Not in general. But it should work for the typical and import use cases. And that is exactly the reason why I delivered the proof that this typical use case works with Autodesk Mesh Mixer: It can be solved. Autodesk already did it. 4. "These function were never supposed to work for very ill-formed triangles as from the above stls." Ill? This is the real world. Ideal would be better but reality requires tolerence to non ideal situations. And Repetier Host can handle this "ill" STL. But it cannot handle the FreeCAD STL export. Conclusion: a) I think it would be helpful first to reproduce the described procedure using Repetier Host and Mesh Mixer. That will show that there exist stability problems that can be solved because Autodesk was able to do that. b) GENERAL case: Meshes + CAD. Seems to be much more work but is import. |
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This is not written as an appropriate bug report, but as a mishmash of arbitrary opinions that should have been posted on the forum first. FreeCAD should need to support Repetier-Host? Please! This is an open source project, focus of development is on *CAD*, which is actually _building_ models in FreeCAD for a variety of uses rather than exclusively importing badly designed meshes from everywhere then expecting FreeCAD will auto-magically fix everything for Repetier-Host. The FreeCAD developers work for free in their spare time, they do not have the resources of Autodesk. And pretending Repetier-Host is the only standard in 3D printing is ludicrous. In any case it has NOTHING to do with CAD. Werner, this "report" really should be closed as invalid because it is mostly BS. |
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"This is not written as an appropriate bug report, but as a mishmash of arbitrary opinions that should have been posted on the forum first." Forum: The problem in general actually is complicated and many people and companies are concerned with it ("mishmash"). Exactly that was the reason why I have delivered concrete problem that can be well reproduced with the described procedure and a hint how to solve (Mesh Mixer). Unfortunately another procedure was used for checking that. But I agree that the problem in general should be discussed in the forum. Especially interesting could be different approaches for a more general solution. Compare Catia approach in w3-mediapool.hm.edu/mediapool/media/fk03/fk03_lokal/verbundlabore/kca/rpmlab/fk03_rp_stl_to_solid_r1.pdf that could be more error tolerant. |
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> glcd_tester_lcr_t4_extra_top.stl I tested the file exported from FreeCAD and Repetier Host (v1.6.2) didn't mention a problem. So, I tried all other files and it reported a non-manifold error for the file glcd_tester_lcr_t4_top.stl. However, this non-manifold already exists in the original version of the file downloaded from thingiverse which btw FreeCAD and MeshLab discover, too. So, after all it shows your bug report and all the conclusions are no longer valid. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2016-07-24 21:47 | vokars | New Issue | |
| 2016-07-25 19:28 | vokars | Note Added: 0007216 | |
| 2016-07-27 22:07 | wmayer | Note Added: 0007218 | |
| 2016-07-31 17:31 | vokars | Note Added: 0007229 | |
| 2016-07-31 21:35 | normandc | Note Added: 0007230 | |
| 2016-07-31 22:31 | vokars | Note Added: 0007235 | |
| 2016-08-07 16:25 | wmayer | Note Added: 0007254 | |
| 2016-08-07 16:25 | wmayer | Status | new => closed |
| 2016-08-07 16:25 | wmayer | Resolution | open => unable to reproduce |
| 2016-08-07 16:25 | wmayer | Fixed in Version | => 0.17 |
