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No longer able to use STLs
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No longer able to use STLs
 
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I used to be able to import STLs and do unions with them, etc. (roughly 1
year ago on Debian 9) I'm trying to import an STL and simply do a union with a cube. The preview shows up fine, but when I render I don't see the STL. I tried removing the union, no luck. I tried moving the cube so it doesn't intersect with the STL, no luck. I tried removing the union and moving the cube, no luck. I tried three different but similar STLs, no luck. Same issue every time. I am using the version of OpenSCAD that ships with Debian 10 (2019.01) and I also tried the app image version. I tried all of the above debugging steps with both versions. I tried swapping the union to a difference and I get: ERROR: CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion violation! Expr: e_below != SHalfedge_handle() File: /usr/include/CGAL/Nef_3/SNC_FM_decorator.h Line: 427 and ERROR: CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion violation! Expr: pe_prev->is_border() || !internal::Plane_constructor<Plane>::get_plane(pe_prev->facet(),pe_prev->facet()->plane()).is_degenerate() File: /usr/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h Line: 251 for older and newer versions respectively. Also seeing: Error !!!!!!!!!!!!!!!!!!!!!!! In the terminal. What sort of error message is that? My STLs are all manifolds. There are no coincident faces. (Although this really should not be an issue, as a 3d modeler I'm trying to match lines to existing lines as best I can! I can offset by 0.1 if I really have to, but that seems asinine) I believe 2015.03 was the last version that worked for me, but unfortunately there are no appimages for older releases. How do I solve this issue? I have sunk so much time into learning OpenSCAD, it's now useless for me. :( -- Sent from: http://forum.openscad.org/ _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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guaranteed_interwoven wrote
> ERROR: CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion > violation! Expr: e_below != SHalfedge_handle() File: > /usr/include/CGAL/Nef_3/SNC_FM_decorator.h Line: 427 > > and > > ERROR: CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion > violation! Expr: pe_prev->is_border() || > !internal::Plane_constructor > <Plane> > ::get_plane(pe_prev->facet(),pe_prev->facet()->plane()).is_degenerate() > File: /usr/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h Line: 251 > > for older and newer versions respectively. > > Also seeing: > Error !!!!!!!!!!!!!!!!!!!!!!! > > In the terminal. What sort of error message is that? > > My STLs are all manifolds. There are no coincident faces. Those are CGAL errors, the tool used to render the geometry. You get the error only when CGAL is called, so a import alone does not call CGAL, but a union with a cube will. Those error say CGAL is not happy with your STL, ie it is not valid. e.g. assertion violation! Expr: e_below != SHalfedge_handle() is CGAL checking the edge below is the same as the half edge. Check for self-intersections. If you share the STL I'll have a look at it. > Also seeing: > Error !!!!!!!!!!!!!!!!!!!!!!! > In the terminal. What sort of error message is that? Could you post a screen capture, I've never seem anything like that. ----- Admin - email* me if you need anything, or if I've done something stupid... * click on my MichaelAtOz label, there is a link to email me. Unless specifically shown otherwise above, my contribution is in the Public Domain; to the extent possible under law, I have waived all copyright and related or neighbouring rights to this work. Obviously inclusion of works of previous authors is not included in the above. -- Sent from: http://forum.openscad.org/ _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
OpenSCAD Admin - email* me if you need anything, or if I've done something stupid...
* on the Forum, click on my MichaelAtOz label, there is a link to email me. Unless specifically shown otherwise above, my contribution is in the Public Domain; to the extent possible under law, I have waived all copyright and related or neighbouring rights to this work. Obviously inclusion of works of previous authors is not included in the above. |
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In reply to this post by guaranteed_interwoven
On 2020-04-17 06:33, guaranteed_interwoven wrote:
> I used to be able to import STLs and do unions with them, etc. (roughly > 1 > year ago on Debian 9) STL files are inherently troublesome and are not well suited for import in other systems. Try one of the available mesh repair tools such as e.g. MeshLab. If you want more help you could make the offending STL available and I can have a look at it using polyfix (part of AngelCAD). Regards Carsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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In reply to this post by guaranteed_interwoven
On 17.04.20 06:33, guaranteed_interwoven wrote:
> Also seeing: > Error !!!!!!!!!!!!!!!!!!!!!!! > > In the terminal. What sort of error message is that? That you have to ask the CGAL people: https://github.com/CGAL/cgal/blob/master/Nef_3/include/CGAL/Nef_3/polygon_mesh_to_nef_3.h#L75-L106 ciao, Torsten. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
-- Torsten
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On 2020-04-17 15:37, Torsten Paul wrote:
> On 17.04.20 06:33, guaranteed_interwoven wrote: >> Also seeing: >> Error !!!!!!!!!!!!!!!!!!!!!!! >> >> In the terminal. What sort of error message is that? > > That you have to ask the CGAL people: > > https://github.com/CGAL/cgal/blob/master/Nef_3/include/CGAL/Nef_3/polygon_mesh_to_nef_3.h#L75-L106 Or you could read that code. It says the face normal is a null vector after computing it with Newell's Method. It means there is a triangle in the STL that is collapsed. Bad message, but that it what it means. That can probably be fixed using one of the repair tools. Carsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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In reply to this post by tp3
On Fri, Apr 17, 2020 at 03:37:25PM +0200, Torsten Paul wrote:
> On 17.04.20 06:33, guaranteed_interwoven wrote: > > Also seeing: > > Error !!!!!!!!!!!!!!!!!!!!!!! > > > > In the terminal. What sort of error message is that? > > That you have to ask the CGAL people: > > https://github.com/CGAL/cgal/blob/master/Nef_3/include/CGAL/Nef_3/polygon_mesh_to_nef_3.h#L75-L106 I've created a pull request. https://github.com/CGAL/cgal/pull/4663 Roger. -- ** [hidden email] ** https://www.BitWizard.nl/ ** +31-15-2049110 ** ** Delftechpark 11 2628 XJ Delft, The Netherlands. KVK: 27239233 ** The plan was simple, like my brother-in-law Phil. But unlike Phil, this plan just might work. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
Re: No longer able to use STLs
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In reply to this post by MichaelAtOz
Thank you for the help! This is driving me nuts. I *used* to be able to do
this sort of thing with OpenSCAD all day long and never run into an issue. floor.stl <http://forum.openscad.org/file/t2594/floor.stl> union() { translate([0, 0, 6]) scale([0.9842519685, 0.9842519685, 1]) import("floor.stl"); cube([50, 50, 6]); } -- Sent from: http://forum.openscad.org/ _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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Self intersections, via NetFabb:
<http://forum.openscad.org/file/t359/floor-si-Capture.jpg> Note also the thinner triangles to the left. Unfortunately my Meshlab is crashing when I try anything with it... Carsten? ----- Admin - email* me if you need anything, or if I've done something stupid... * click on my MichaelAtOz label, there is a link to email me. Unless specifically shown otherwise above, my contribution is in the Public Domain; to the extent possible under law, I have waived all copyright and related or neighbouring rights to this work. Obviously inclusion of works of previous authors is not included in the above. -- Sent from: http://forum.openscad.org/ _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org
OpenSCAD Admin - email* me if you need anything, or if I've done something stupid...
* on the Forum, click on my MichaelAtOz label, there is a link to email me. Unless specifically shown otherwise above, my contribution is in the Public Domain; to the extent possible under law, I have waived all copyright and related or neighbouring rights to this work. Obviously inclusion of works of previous authors is not included in the above. |
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> I *used* to be able to do this sort of thing with OpenSCAD all day long and never run into an issue. I think you must have just been lucky. OpenSCAD has never accepted broken STLs and doesn't accept some valid ones and even some it has produced itself. Perhaps import should always try passing the mesh to CGAL, catch the exception and report it is a broken STL. That would stop the endless reports of "I can import my STL and it looks fine but CGS ops fail." On Fri, 17 Apr 2020 at 23:43, MichaelAtOz <[hidden email]> wrote: Self intersections, via NetFabb: _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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In reply to this post by cacb
On Fri, Apr 17, 2020 at 05:21:43PM +0200, [hidden email] wrote:
> On 2020-04-17 15:37, Torsten Paul wrote: > >On 17.04.20 06:33, guaranteed_interwoven wrote: > >>Also seeing: > >>Error !!!!!!!!!!!!!!!!!!!!!!! > >> > >>In the terminal. What sort of error message is that? > > > >That you have to ask the CGAL people: > > > >https://github.com/CGAL/cgal/blob/master/Nef_3/include/CGAL/Nef_3/polygon_mesh_to_nef_3.h#L75-L106 > > Or you could read that code. It says the face normal is a null > vector after computing it with Newell's Method. It means there is a > triangle in the STL that is collapsed. Bad message, but that it what > it means. That can probably be fixed using one of the repair tools. So it is a zero area triangle. Hmm. I went ahead and improved the error message. I created a pull request, and I was told it was accepted. (I don't see it under the link above). But I thought STLs had normal vectors inside them and that the vector compared there was from the file. You're saying it is computed and indicates a zero-surface-area triangle? Roger. -- ** [hidden email] ** https://www.BitWizard.nl/ ** +31-15-2049110 ** ** Delftechpark 11 2628 XJ Delft, The Netherlands. KVK: 27239233 ** The plan was simple, like my brother-in-law Phil. But unlike Phil, this plan just might work. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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There are normals in STL files but a lot of applications ignore them and compute their own. In the case of OpenSCAD it converts STLs to PolySets that don't have normals. Then it converts it to nef_3 format for CGAL and presumably CGAL calculates its own normals. On Sat, 18 Apr 2020 at 09:13, Rogier Wolff <[hidden email]> wrote: On Fri, Apr 17, 2020 at 05:21:43PM +0200, [hidden email] wrote: _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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In reply to this post by guaranteed_interwoven
On 17.04.2020 23:28, guaranteed_interwoven wrote:
> Thank you for the help! This is driving me nuts. I *used* to be able to do > this sort of thing with OpenSCAD all day long and never run into an issue. > > floor.stl <http://forum.openscad.org/file/t2594/floor.stl> > > union() > { > translate([0, 0, 6]) > scale([0.9842519685, 0.9842519685, 1]) > import("floor.stl"); > cube([50, 50, 6]); > } > See the fix here, including original bad file + repaired file https://gist.github.com/arnholm/49c52c130240184460668c281e8307c2 In summary this was fixed easily using AngelCADs polyfix. $ polyfix floor.stl Parameters: input_file = floor.stl polyhedron 0 ================= volume=10890.5, dtol=0.01, atol=1e-06, maxiter=10 iteration 0: vertices=92100 faces=30700 warning: 1 zero area faces. warning: nonmanifold edges: uc(1)=92100 merged 76748 vertices removed 1 collapsed or zero area face split 1 face total changes=76750 no warnings iteration 1: vertices=15352 faces=30700 total changes=0 no warnings Summary: polyhedron 0: vertices=15352 faces=30700 : no warnings Writing: floor_1.stl ... polyfix finished, time used: 0d 00h 00m 01s It detected one zero area face which was removed, another face was split in 2 parts. After that the repaored file had no warning and was imported into OpenSCAD and "F6'ed" without any problems Carsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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In reply to this post by MichaelAtOz
On 18.04.2020 00:42, MichaelAtOz wrote:
> Self intersections, via NetFabb: > <http://forum.openscad.org/file/t359/floor-si-Capture.jpg> > Note also the thinner triangles to the left. > Unfortunately my Meshlab is crashing when I try anything with it... > > Carsten? https://gist.github.com/arnholm/49c52c130240184460668c281e8307c2 Not every repair tool behaves the same. In this case there were 2 offending faces, one collapsed face and another one needing to be split in order to make the model 2-manifold. Looks like Meshlab does not account for one of those (I didn't try). Polyfix fixed it with ease in this case. Carsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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In reply to this post by rew
On 18.04.2020 10:12, Rogier Wolff wrote:
> But I thought STLs had normal vectors inside them and that the vector > compared there was from the file. You're saying it is computed and > indicates a zero-surface-area triangle? The STL file format is badly designed. The normal vectors stored is at best consistent with the vertex coordinates, sometimes they are not. The best thing to do is to ignore the stored normal and compute it from the vertex coordinates when required. But different code does different things in this area, another reason among others why STL files are probably the worst possible choice for exchanging models between applications. I didn't study every detail of the CGAL code, but I guess the normal is computed yes. Catrsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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In reply to this post by cacb
On 18.04.2020 10:50, Carsten Arnholm wrote:
> See the fix here, including original bad file + repaired file > https://gist.github.com/arnholm/49c52c130240184460668c281e8307c2 Something happened when uploading the STLs to github, they became corrupted during upload. I have re-uploaded them now and it seems ok. The file should display fine You can get copies of the files using "git glone" and the URL above Carsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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On 18.04.2020 11:25, Carsten Arnholm wrote:
> On 18.04.2020 10:50, Carsten Arnholm wrote: >> See the fix here, including original bad file + repaired file >> https://gist.github.com/arnholm/49c52c130240184460668c281e8307c2 > > You can get copies of the files using "git glone" and the URL above That should be "git clone" obviously. Sorry. Carsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
Re: No longer able to use STLs
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In reply to this post by nophead
> Perhaps import should always try passing the mesh to CGAL, catch the
exception and report it is a broken STL. That would stop the endless reports of "I can import my STL and it looks fine but CGS ops fail." I would certainly appreciate that. When I load the STL in slic3r, there are certainly no errors being reported and it does report the STL as a manifold, so I was under the impression the problem was with OpenSCAD, not with the STL. -- Sent from: http://forum.openscad.org/ _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
Re: No longer able to use STLs
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In reply to this post by cacb
Thank you! I installed angelcad and it worked perfectly.
I am 100% happy with an STL repair tool. Thank you everyone for your help here! -- Sent from: http://forum.openscad.org/ _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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The STL has to be perfect for OpenSCAD to accept it. No degenerate triangles and no self intersections. I think the CGAL errors are 100% right about the mesh passed to it. I.e. no false positives but because OpenSCAD snaps everything to a grid it can't have very close vertices or snapping them will cause degenerate triangles and self intersections.
On Mon, 20 Apr 2020 at 05:34, guaranteed_interwoven <[hidden email]> wrote: Thank you! I installed angelcad and it worked perfectly. _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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In reply to this post by guaranteed_interwoven
On 2020-04-20 06:33, guaranteed_interwoven wrote:
> Thank you! I installed angelcad and it worked perfectly. > > I am 100% happy with an STL repair tool. > > Thank you everyone for your help here! Thanks for the confirmation and feedback! Repairing STL using such tools is sometimes possible, but not in every case. STL is such a poor format that it is possible to write unusable stuff to it. Carsten Arnholm _______________________________________________ OpenSCAD mailing list [hidden email] http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org |
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