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no way to render difference with stl

J
juerg.maier
Sat, Feb 18, 2017 2:16 PM

I truly love OpenScad but it has its problems with imported STL-Files.
I have a partial globe land profile (cut down for size). I can render it. If
I try to difference it from my globe-sphere it throws
ERROR: CGAL error in CGAL_Nef_polyhedron3():
I have tried to fix the STL with netfabb, netfabb cloud, meshmixer and
Microsoft stl repair.
I am out of ideas how to make it work.
I want to subtract the land from a globe sphere to print the land parts in a
second color.  land7_Cut3_fixed_2_MM.stl
http://forum.openscad.org/file/n20473/land7_Cut3_fixed_2_MM.stl

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I truly love OpenScad but it has its problems with imported STL-Files. I have a partial globe land profile (cut down for size). I can render it. If I try to difference it from my globe-sphere it throws ERROR: CGAL error in CGAL_Nef_polyhedron3(): I have tried to fix the STL with netfabb, netfabb cloud, meshmixer and Microsoft stl repair. I am out of ideas how to make it work. I want to subtract the land from a globe sphere to print the land parts in a second color. land7_Cut3_fixed_2_MM.stl <http://forum.openscad.org/file/n20473/land7_Cut3_fixed_2_MM.stl> -- View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473.html Sent from the OpenSCAD mailing list archive at Nabble.com.
FV
Frank van der Hulst
Sat, Feb 18, 2017 6:25 PM

I looked at your file with FreeCAD... it finds (and sometimes fixes) faults
the others don't.

It shows 3 or 4 large triangular holes in Antartica due apparently to
flipped normals. And reports quite a lot of other faults. Automatically
fixing them didn't work.

You could also try MeshLab to find and fix the faults.

On Sun, Feb 19, 2017 at 3:16 AM, juerg.maier juerg.maier@pobox.ch wrote:

I truly love OpenScad but it has its problems with imported STL-Files.
I have a partial globe land profile (cut down for size). I can render it.
If
I try to difference it from my globe-sphere it throws
ERROR: CGAL error in CGAL_Nef_polyhedron3():
I have tried to fix the STL with netfabb, netfabb cloud, meshmixer and
Microsoft stl repair.
I am out of ideas how to make it work.
I want to subtract the land from a globe sphere to print the land parts in
a
second color.  land7_Cut3_fixed_2_MM.stl
http://forum.openscad.org/file/n20473/land7_Cut3_fixed_2_MM.stl

--
View this message in context: http://forum.openscad.org/no-
way-to-render-difference-with-stl-tp20473.html
Sent from the OpenSCAD mailing list archive at Nabble.com.

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I looked at your file with FreeCAD... it finds (and sometimes fixes) faults the others don't. It shows 3 or 4 large triangular holes in Antartica due apparently to flipped normals. And reports quite a lot of other faults. Automatically fixing them didn't work. You could also try MeshLab to find and fix the faults. On Sun, Feb 19, 2017 at 3:16 AM, juerg.maier <juerg.maier@pobox.ch> wrote: > I truly love OpenScad but it has its problems with imported STL-Files. > I have a partial globe land profile (cut down for size). I can render it. > If > I try to difference it from my globe-sphere it throws > ERROR: CGAL error in CGAL_Nef_polyhedron3(): > I have tried to fix the STL with netfabb, netfabb cloud, meshmixer and > Microsoft stl repair. > I am out of ideas how to make it work. > I want to subtract the land from a globe sphere to print the land parts in > a > second color. land7_Cut3_fixed_2_MM.stl > <http://forum.openscad.org/file/n20473/land7_Cut3_fixed_2_MM.stl> > > > > -- > View this message in context: http://forum.openscad.org/no- > way-to-render-difference-with-stl-tp20473.html > Sent from the OpenSCAD mailing list archive at Nabble.com. > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >
M
MichaelAtOz
Sat, Feb 18, 2017 9:15 PM

Meshlab show self intersection and non-manifold.
I haven't learnt sufficient skills in Meshlab to fix it.

Admin - PM me if you need anything, or if I've done something stupid...

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.

The TPP is no simple “trade agreement.”  Fight it! http://www.ourfairdeal.org/  time is running out!

View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473p20477.html
Sent from the OpenSCAD mailing list archive at Nabble.com.

Meshlab show self intersection and non-manifold. I haven't learnt sufficient skills in Meshlab to fix it. ----- Admin - PM me if you need anything, or if I've done something stupid... 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. The TPP is no simple “trade agreement.” Fight it! http://www.ourfairdeal.org/ time is running out! -- View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473p20477.html Sent from the OpenSCAD mailing list archive at Nabble.com.
N
Neon22
Sun, Feb 19, 2017 2:18 AM

Those holes in Antarctica are how you get through to middle earth... Its also
explains why they are inside out.

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View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473p20482.html
Sent from the OpenSCAD mailing list archive at Nabble.com.

Those holes in Antarctica are how you get through to middle earth... Its also explains why they are inside out. -- View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473p20482.html Sent from the OpenSCAD mailing list archive at Nabble.com.
J
juerg.maier
Sun, Feb 19, 2017 11:32 AM

But why are the different programs able to show mit the object and telling me
the file is OK?
And why can I see results with F5 but it fails when using F6?
It would need something like a accuracy factor to make me create a new STL
in OpenScad?

--
View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473p20488.html
Sent from the OpenSCAD mailing list archive at Nabble.com.

But why are the different programs able to show mit the object and telling me the file is OK? And why can I see results with F5 but it fails when using F6? It would need something like a accuracy factor to make me create a new STL in OpenScad? -- View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473p20488.html Sent from the OpenSCAD mailing list archive at Nabble.com.
M
MichaelAtOz
Sun, Feb 19, 2017 12:56 PM

juerg.maier wrote

But why are the different programs able to show mit the object and telling
me the file is OK?
And why can I see results with F5 but it fails when using F6?
It would need something like a accuracy factor to make me create a new STL
in OpenScad?

F5 is a preview, an approximation, it does not calculate exact geometry.
F6, when it needs to do union() difference() etc, uses the geometry.
IF THE GEOMETRY IS BROKEN, SEE ABOVE, IT CANNOT WORK.

Unfortunately other programs take garbage-in and do garbage-out.

Admin - PM me if you need anything, or if I've done something stupid...

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.

The TPP is no simple “trade agreement.”  Fight it! http://www.ourfairdeal.org/  time is running out!

View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473p20490.html
Sent from the OpenSCAD mailing list archive at Nabble.com.

juerg.maier wrote > But why are the different programs able to show mit the object and telling > me the file is OK? > And why can I see results with F5 but it fails when using F6? > It would need something like a accuracy factor to make me create a new STL > in OpenScad? F5 is a preview, an approximation, it does not calculate exact geometry. F6, when it needs to do union() difference() etc, uses the geometry. IF THE GEOMETRY IS BROKEN, SEE ABOVE, IT CANNOT WORK. Unfortunately other programs take garbage-in and do garbage-out. ----- Admin - PM me if you need anything, or if I've done something stupid... 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. The TPP is no simple “trade agreement.” Fight it! http://www.ourfairdeal.org/ time is running out! -- View this message in context: http://forum.openscad.org/no-way-to-render-difference-with-stl-tp20473p20490.html Sent from the OpenSCAD mailing list archive at Nabble.com.
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