damaged STL file?

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damaged STL file?

jon_bondy
This file will not slice properly.  NetFabb says that it has no defects,
but even after repairing it, it will not slice properly. Can any of you
find a problem with it, and if so, with what tools?

http://www.jonbondy.com/sample.stl

Thanks!

Jon

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Re: damaged STL file?

nophead
NetFabb tells me it has degenerate triangles near each eye, the nose and the chin. It can remove them if you tell it to, it doesn't by default.


On 25 February 2018 at 16:09, jon <[hidden email]> wrote:
This file will not slice properly.  NetFabb says that it has no defects, but even after repairing it, it will not slice properly. Can any of you find a problem with it, and if so, with what tools?

http://www.jonbondy.com/sample.stl

Thanks!

Jon

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sample(repaired).stl (5M) Download Attachment
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Re: damaged STL file?

codifies
In reply to this post by jon_bondy
the prusa version of sli3r seems to be able to handle it, but I think I
can see the problem areas, either side of the nostrils there are two
holes after slicing, it may help you track down the issue...


On 25/02/18 16:09, jon wrote:

> This file will not slice properly.  NetFabb says that it has no
> defects, but even after repairing it, it will not slice properly. Can
> any of you find a problem with it, and if so, with what tools?
>
> http://www.jonbondy.com/sample.stl
>
> Thanks!
>
> Jon
>


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Re: damaged STL file?

Ronaldo
In reply to this post by jon_bondy
I had no trouble rendering it with OpenSCAD or slicing it with Simplify3d.


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Re: damaged STL file?

fred_dot_u
In reply to this post by jon_bondy
I loaded the STL file into Meshmixer, Analysis, Inspector and had no errors.
I loaded the STL file into S3D and checked for non-manifold edges, none
found. When the second test on the list was run, Identify Self Intersecting
Surfaces, both the front and back faces of the monolith have an alert that
begins at the point of the chin, running downward to the right (referenced
from the front, protruding portion) to the intersection of the monolith and
the base.
<http://forum.openscad.org/file/t824/facetestslice.jpg>

I'm not sure why Meshmixer misses it.

When I run the preview in S3D, it proceeds beyond the alleged failure point
with no indication of failure, even though I did not perform the suggested
repair:

<http://forum.openscad.org/file/t824/facetestslice2.jpg>

Not necessarily a slicing or model error, the face gets rather thin and
becomes open above the nostrils:

<http://forum.openscad.org/file/t824/facetestslice3.jpg>

I'm not particularly qualified in Blender 2.75.1, but am aware there are 3D
modeling tools within. I ran the All Checks and the return was substantial.
I don't know enough to resolve them within Blender, however:

<http://forum.openscad.org/file/t824/facetestslice4.jpg>



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Re: damaged STL file?

Ronaldo
In reply to this post by codifies
2018-02-25 13:34 GMT-03:00 Chris Camacho <[hidden email]>:
the prusa version of sli3r seems to be able to handle it, but I think I can see the problem areas, either side of the nostrils there are two holes after slicing, it may help you track down the issue...

You are right but I don't see how this could be indigestible to any reasonable slicer.







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Re: damaged STL file?

jon_bondy
In reply to this post by codifies

Interesting.  When I look at the STL using NetFabb as a viewer, I don't see holes (which is why I was mystified).  Both IdeaMaker and CraftWare come up with bizarre slices (IdeaMaker does worse than CraftWare).  Here is the IdeaMaker slice.  I would like to keep using IdeaMaker, so what I was looking for was a way to modify/fix the STL.  The fact that I cannot see the holes in NetFabb makes that difficult to do.



On 2/25/2018 11:34 AM, Chris Camacho wrote:
the prusa version of sli3r seems to be able to handle it, but I think I can see the problem areas, either side of the nostrils there are two holes after slicing, it may help you track down the issue...


On 25/02/18 16:09, jon wrote:
This file will not slice properly.  NetFabb says that it has no defects, but even after repairing it, it will not slice properly. Can any of you find a problem with it, and if so, with what tools?

http://www.jonbondy.com/sample.stl

Thanks!

Jon



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Re: damaged STL file?

jon_bondy
In reply to this post by fred_dot_u
Very cool!

I can see where the slicer got confused.  There is that narrow part, and
with the spiral slicing, it needs to put two beads of filament where
there is barely room for one.  Still, I agree with the other comments
that a good slicer would work around the problem.  The IdeaMaker slicer
is set up to support the Raise3D N2 printer, so switching slicers would
involve a different kind of adventure.  Probably easier to tweak the STL.

Thanks for all of your help, and so quickly!   You guys rock!

Jon


On 2/25/2018 11:44 AM, fred_dot_u wrote:

> I loaded the STL file into Meshmixer, Analysis, Inspector and had no errors.
> I loaded the STL file into S3D and checked for non-manifold edges, none
> found. When the second test on the list was run, Identify Self Intersecting
> Surfaces, both the front and back faces of the monolith have an alert that
> begins at the point of the chin, running downward to the right (referenced
> from the front, protruding portion) to the intersection of the monolith and
> the base.
> <http://forum.openscad.org/file/t824/facetestslice.jpg>
>
> I'm not sure why Meshmixer misses it.
>
> When I run the preview in S3D, it proceeds beyond the alleged failure point
> with no indication of failure, even though I did not perform the suggested
> repair:
>
> <http://forum.openscad.org/file/t824/facetestslice2.jpg>
>
> Not necessarily a slicing or model error, the face gets rather thin and
> becomes open above the nostrils:
>
> <http://forum.openscad.org/file/t824/facetestslice3.jpg>
>
> I'm not particularly qualified in Blender 2.75.1, but am aware there are 3D
> modeling tools within. I ran the All Checks and the return was substantial.
> I don't know enough to resolve them within Blender, however:
>
> <http://forum.openscad.org/file/t824/facetestslice4.jpg>
>
>
>
> --
> Sent from: http://forum.openscad.org/
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>
>

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Re: damaged STL file?

cacb
In reply to this post by jon_bondy
On 25. feb. 2018 17:09, jon wrote:
> This file will not slice properly.  NetFabb says that it has no defects,
> but even after repairing it, it will not slice properly. Can any of you
> find a problem with it, and if so, with what tools?
>
> http://www.jonbondy.com/sample.stl
>
> Thanks!
> Jon

Hi Jon,

Maybe this helps. I did a quick test and my utility found and fixed some
issues:

download link (2 day expiry)
https://www.expirebox.com/download/0bcbf69f4f408349b2b48b8605957954.html

More details in the log below

abm_polyfix -zip sample.stl

Parameters:
   input_file = sample.stl
          zip =

polyhedron 0 ================= volume=73528.4, dtol=0.01, atol=1e-06,
maxiter=10
iteration 0: vertices=249000 faces=83000
              warning: 7 zero area faces.
              warning: nonmanifold edges: uc(1)=249000
              merged 207669 vertices
              removed 343 collapsed or zero area faces
              split 1 face
              total changes=208013
              no warnings

iteration 1: vertices=41331 faces=82658
              merged 4 vertices
              removed 8 collapsed or zero area faces
              total changes=12
              no warnings

iteration 2: vertices=41327 faces=82650
              merged 2 vertices
              removed 4 collapsed or zero area faces
              total changes=6
              no warnings

iteration 3: vertices=41325 faces=82646
              total changes=0
              no warnings

Summary:
              polyhedron 0: vertices=41325 faces=82646 : no warnings

Writing: sample_polyfix.zip

... abm_polyfix finished, time used: 0d 00h 00m 05s


Regards
Carsten Arnholm

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Re: damaged STL file?

Ronaldo
In reply to this post by jon_bondy
I don't think Netfab or any other software will be able to repair the "holes" in your stl because the file represents a watertight model (with some degenerated triangles). In fact, the holes are model genus like in a torus or in a perforated cube. To repair it manually is a very hard task due to the high number of triangles. So, either you regenerate the model increasing its thickness (in such a way the negative mask doesn't touch the positive one), or give up using spiral vase.

2018-02-25 13:45 GMT-03:00 jon <[hidden email]>:

Interesting.  When I look at the STL using NetFabb as a viewer, I don't see holes (which is why I was mystified).  Both IdeaMaker and CraftWare come up with bizarre slices (IdeaMaker does worse than CraftWare).  Here is the IdeaMaker slice.  I would like to keep using IdeaMaker, so what I was looking for was a way to modify/fix the STL.  The fact that I cannot see the holes in NetFabb makes that difficult to do.




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Re: damaged STL file?

Ronaldo
Revising the model with Simplify3d, I can see the holes in it only after slicing. It seems that the distance between the front and back surfaces in those areas is much smaller than the filament thread diameter and the slicer ignore them. Also, there is no observable holes when the model is loaded in Sketchup (I load it with a fair scale up). So, it seems that there is no genus in the model but a very very thin wall in some areas.

2018-02-25 19:16 GMT-03:00 Ronaldo Persiano <[hidden email]>:
I don't think Netfab or any other software will be able to repair the "holes" in your stl because the file represents a watertight model (with some degenerated triangles). In fact, the holes are model genus like in a torus or in a perforated cube. To repair it manually is a very hard task due to the high number of triangles. So, either you regenerate the model increasing its thickness (in such a way the negative mask doesn't touch the positive one), or give up using spiral vase. 

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Re: damaged STL file?

MichaelAtOz
Administrator
In reply to this post by jon_bondy
jon_bondy wrote
> Interesting.  When I look at the STL using NetFabb as a viewer, I don't
> see holes (which is why I was mystified). 

As Nophead said (his post was delayed, needing approval due to its size
BTW), NetFabb shows it has degenerate triangles. Unlike other issues, it
does not flag these with the big RED Cross.
You need to click on the Red Cross icon, make sure the check box is
selected, also press Update.

You see them as red lines:
<http://forum.openscad.org/file/t359/jon_face_sample.jpg>

These can generally be fixed (I've had ones it could not), via
Repair/Remove-Degenerated-Faces, I also do an auto repair after JIC.
Nopehead's post/email has the fixed STL attached.

BTW Jon, did you flatten the face to reduce overhangs?? Sorta looks that
way...



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Re: damaged STL file?

jon_bondy
In reply to this post by cacb
Carsten:

That certainly did fix the problem!  Your tool gets better and better!

Thanks!

Jon


On 2/25/2018 3:26 PM, Carsten Arnholm wrote:

> On 25. feb. 2018 17:09, jon wrote:
>> This file will not slice properly. NetFabb says that it has no
>> defects, but even after repairing it, it will not slice properly. Can
>> any of you find a problem with it, and if so, with what tools?
>>
>> http://www.jonbondy.com/sample.stl
>>
>> Thanks!
>> Jon
>
> Hi Jon,
>
> Maybe this helps. I did a quick test and my utility found and fixed
> some issues:
>
> download link (2 day expiry)
> https://www.expirebox.com/download/0bcbf69f4f408349b2b48b8605957954.html
>
> More details in the log below
>
> abm_polyfix -zip sample.stl
>
> Parameters:
>   input_file = sample.stl
>          zip =
>
> polyhedron 0 ================= volume=73528.4, dtol=0.01, atol=1e-06,
> maxiter=10
> iteration 0: vertices=249000 faces=83000
>              warning: 7 zero area faces.
>              warning: nonmanifold edges: uc(1)=249000
>              merged 207669 vertices
>              removed 343 collapsed or zero area faces
>              split 1 face
>              total changes=208013
>              no warnings
>
> iteration 1: vertices=41331 faces=82658
>              merged 4 vertices
>              removed 8 collapsed or zero area faces
>              total changes=12
>              no warnings
>
> iteration 2: vertices=41327 faces=82650
>              merged 2 vertices
>              removed 4 collapsed or zero area faces
>              total changes=6
>              no warnings
>
> iteration 3: vertices=41325 faces=82646
>              total changes=0
>              no warnings
>
> Summary:
>              polyhedron 0: vertices=41325 faces=82646 : no warnings
>
> Writing: sample_polyfix.zip
>
> ... abm_polyfix finished, time used: 0d 00h 00m 05s
>
>
> Regards
> Carsten Arnholm
>
> _______________________________________________
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Re: damaged STL file?

Gadgetmind
In reply to this post by cacb
On 25/02/18 20:26, Carsten Arnholm wrote:

Maybe this helps. I did a quick test and my utility found and fixed some issues:

I guess I'm been asleep, which utility?



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Re: damaged STL file?

cacb
On 2018-02-26 10:31, Gadgetmind wrote:
> On 25/02/18 20:26, Carsten Arnholm wrote:
>
>> Maybe this helps. I did a quick test and my utility found and fixed
>> some issues:
>
> I guess I'm been asleep, which utility?

It is a C++ utility I wrote (working name "abm_polyfix") for analyzing
and repairing polyhedra, reading from STL or AMF. It eliminates/merges
close vertices, eliminates zero area faces of various kinds, plus fixes
some non-manifold issues by splitting faces, etc.

Carsten Arnholm

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Re: damaged STL file?

Gadgetmind
On 26/02/18 10:36, [hidden email] wrote:
It is a C++ utility I wrote (working name "abm_polyfix") for analyzing and repairing polyhedra, reading from STL or AMF. It eliminates/merges close vertices, eliminates zero area faces of various kinds, plus fixes some non-manifold issues by splitting faces, etc.

Cool. Is it available for others to try? Linux friendly?



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Re: damaged STL file?

cacb
On 2018-02-26 11:51, Gadgetmind wrote:
> On 26/02/18 10:36, [hidden email] wrote:
>
>> It is a C++ utility I wrote (working name "abm_polyfix") for
>> analyzing and repairing polyhedra, reading from STL or AMF. It
>> eliminates/merges close vertices, eliminates zero area faces of
>> various kinds, plus fixes some non-manifold issues by splitting
>> faces, etc.
>
> Cool. Is it available for others to try? Linux friendly?

The idea is to eventually provide a web service with this + more. This
is ongoing, if delayed. "abm_polyfix" runs on Windows and Linux like
everything I do.

In general I think the thread illustrates the somewhat fuzzy nature of
repairing problematic polyhedra in general and STL files in particular
(STLs do not provide any topology, it must be guessed). Several repair
tools exist but they appear to make different assumptions leading to
different results.

Carsten Arnholm

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Re: damaged STL file?

JordanBrown
On 2/26/2018 7:41 AM, [hidden email] wrote:
In general I think the thread illustrates the somewhat fuzzy nature of repairing problematic polyhedra in general and STL files in particular (STLs do not provide any topology, it must be guessed). Several repair tools exist but they appear to make different assumptions leading to different results.

Are there other file formats that would be better?  Getting designers like OpenSCAD and slicers to *both* implement something new would be tough, but if there are clear benefits maybe it could be done.


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Re: damaged STL file?

cacb
On 26. feb. 2018 18:35, Jordan Brown wrote:
> Are there other file formats that would be better?  Getting designers
> like OpenSCAD and slicers to *both* implement something new would be
> tough, but if there are clear benefits maybe it could be done.

Yes, there are better formats (see below), but STL seems so entrenched
that it is very hard to get wide enough support for anything else. Some
requirements to a non-STL format I guess would be

1) Suited for polyhedron exchange between CAD applications, not just CAD
to slicers.

2) Unambiguous format, with explicit topology

3) Efficient binary storage, plus equivalent ascii text version with
same info. Binary/Ascii should be transparent to users.

4) It must be *very* simple.

etc.

OpenSCAD already support other 3D formats in addition to STL

OFF - http://paulbourke.net/dataformats/off/
AMF - https://en.wikipedia.org/wiki/Additive_Manufacturing_File_Format

Both of the above satisfy 1) and 2). AMF in its simplest form is quite
nice, but not terribly efficient, plus in my opinion it forgets 4) so it
will never become universal. OFF is a nice contender, but it does not
seem to be simple enough to be popular.

STL is both wasteful and ambiguous, it is just a sea of free floating
triangles. The binary format does not contain the same info as the text
format, etc. Its popularity is due to history only.

It seems to me super simplicity is a key. So any alternative format
should be even simpler than STL. Given that existing alternatives are
not very popular, we might as well propose something new to compete,
making simplicity the key feature while fixing some of the STL issues.
In my mind it could be something like

* simple file header to identify ASCII/Binary
* vertex coordinates stored only once
* triangle faces only
* faces defined by references to vertices, implicit normals

In other words, just the bare minimum, equivalent to the info that goes
into OpenSCAD polyhedron command. The text format would be more compact
than STL and simpler to read. The binary format would also be more
compact than STL since coordinates would be mentioned only once, and
therefore also not have any issues with interpretation.

You could say it is far too simple. But if you want it to be widely
adopted it must be extremely simple and fast. We could call it STL2 and
say it is how STL should have been defined in 1985 or so :-)

I don't have any illusions it would be successful, but if it was adopted
I think it would be helpful in avoiding some of the "damaged STL" issues
(not all) and enable easier sharing of models between various applications.

Just my thoughts, nothing else.

Carsten Arnholm

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Re: damaged STL file?

nophead
STL is unambiguous if it is written correctly and only used to represent a manifold model with no self intersections. That is sufficient for 3D printing as all 3D printed objects are manifold.

While other representations can also represent non-manifold objects it pushes the problem downstream. How do you print a non-manifold object?



On 26 February 2018 at 19:44, Carsten Arnholm <[hidden email]> wrote:
On 26. feb. 2018 18:35, Jordan Brown wrote:
Are there other file formats that would be better?  Getting designers like OpenSCAD and slicers to *both* implement something new would be tough, but if there are clear benefits maybe it could be done.

Yes, there are better formats (see below), but STL seems so entrenched that it is very hard to get wide enough support for anything else. Some requirements to a non-STL format I guess would be

1) Suited for polyhedron exchange between CAD applications, not just CAD to slicers.

2) Unambiguous format, with explicit topology

3) Efficient binary storage, plus equivalent ascii text version with same info. Binary/Ascii should be transparent to users.

4) It must be *very* simple.

etc.

OpenSCAD already support other 3D formats in addition to STL

OFF - http://paulbourke.net/dataformats/off/
AMF - https://en.wikipedia.org/wiki/Additive_Manufacturing_File_Format

Both of the above satisfy 1) and 2). AMF in its simplest form is quite nice, but not terribly efficient, plus in my opinion it forgets 4) so it will never become universal. OFF is a nice contender, but it does not seem to be simple enough to be popular.

STL is both wasteful and ambiguous, it is just a sea of free floating triangles. The binary format does not contain the same info as the text format, etc. Its popularity is due to history only.

It seems to me super simplicity is a key. So any alternative format should be even simpler than STL. Given that existing alternatives are not very popular, we might as well propose something new to compete, making simplicity the key feature while fixing some of the STL issues. In my mind it could be something like

* simple file header to identify ASCII/Binary
* vertex coordinates stored only once
* triangle faces only
* faces defined by references to vertices, implicit normals

In other words, just the bare minimum, equivalent to the info that goes into OpenSCAD polyhedron command. The text format would be more compact than STL and simpler to read. The binary format would also be more compact than STL since coordinates would be mentioned only once, and therefore also not have any issues with interpretation.

You could say it is far too simple. But if you want it to be widely adopted it must be extremely simple and fast. We could call it STL2 and say it is how STL should have been defined in 1985 or so :-)

I don't have any illusions it would be successful, but if it was adopted I think it would be helpful in avoiding some of the "damaged STL" issues (not all) and enable easier sharing of models between various applications.

Just my thoughts, nothing else.


Carsten Arnholm

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