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Another inverted normals issue [message #3408] Wed, 18 March 2009 13:00 UTC Go to next message
avatar PeterHermans  is currently offline PeterHermans
Messages: 39
Registered: September 2008
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Hello,

I'm having a problem with my car model, continuing on from this topic.

Magics shows there are no errors (although overlappig triangles are tolerance dependant) but whatever I try the Shapeways validation says there are inverted normals.
I could be wrong, but unlike overlapping triangles that are considered overlapping or not, depending on tolerances, normals are either pointing one way or the other... so where is the error?

Is it in the model, but magics cannot detect it?
Is it in magics, wrongfully saying the model is ok?
Is it in the shapeways validation?

Note: I first tried uploading different versions that were hollowed out, with the same result.

Daddymack tried helping me out, but so far no luck.

http://www.student.tue.nl/q/p.r.hermans/50mmcheck.jpg

Re: Another inverted normals issue [message #3409 is a reply to message #3408 ] Wed, 18 March 2009 13:09 UTC Go to previous messageGo to next message
avatar bartv  is currently offline bartv
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Hi Peter,

could you send the latest version of your model to service@shapeways.com in STL? Then I'll check it out for you.

Thanks!

Bart


Community Manager Europe | Shapeways
Re: Another inverted normals issue [message #3414 is a reply to message #3408 ] Wed, 18 March 2009 21:20 UTC Go to previous messageGo to next message
avatar AO  is currently offline AO
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Hi Peter,

If you and Daddy can't fix ..............
My compliments for your cardesign, very nice.
Did you model it in Rhino?
Aparently everthing is perfect. Did you try to delete the inverted triangels and fill the holes? Its one of the last steps you can do but maybe you should do it from the start.
Just a guess.

Greetings AO
Re: Another inverted normals issue [message #3641 is a reply to message #3408 ] Mon, 30 March 2009 12:25 UTC Go to previous messageGo to next message
avatar PeterHermans  is currently offline PeterHermans
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I finally got it to pass the validation \o/.

I got a screenshot from Bart, from Shapeways, that showed errors in Blender.
I played with the tolerances for overlapping triangles in magics to reproduce this image. Note: I did not succeed in fully reproducing it. With the lowered tolerance settings I worked on removing some errors that were now detected. Today I checked the model in meshlab and had it remove 6 non-manifold polygons that magics apparently did not pick up. Then I went back to magics and rechecked and fixed the remaining errors.

Good news: it worked
Bad news: this is not a fixed procedure that will guarantee success the next time.
We really need more info on the shapeways validation settings so we can find out where the errors are and fix them.

AO:
I modelled it in Cinema4D, a couple years ago.
There are/were no inverted normals; otherwise I would flip, or delete and refill them.

Here's a rendering:
http://shademaster.nl/peter/php/3dstills/a1.jpg
Re: Another inverted normals issue [message #3642 is a reply to message #3641 ] Mon, 30 March 2009 12:54 UTC Go to previous messageGo to next message
avatar frankbuss  is currently offline frankbuss
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Registered: March 2009
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Nice car! I had the same problem with inverted normals. I used ViaCAD and only solids and boolean operations, which worked. Then I added some extruded text, which I assume ViaCAD would create correctly without inverted normals, but it didn't worked. For another model text works. Maybe it has to do with too fine details? I can try to reproduce the problem, if this helps the support but would be easier, if Shapeways could say in detail how the verification process works.
Re: Another inverted normals issue [message #3645 is a reply to message #3641 ] Mon, 30 March 2009 13:21 UTC Go to previous messageGo to next message
avatar AO  is currently offline AO
Messages: 76
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Hi Peter,

Stunning design. Really nice car.
I also noticed last weekend that screwing up the resolution of my model causes more triangels and as a result of that also more problems. Since the triangels are related to the normals ( if I understood well ) then less triangles might be the solution. I also found triangel problems if angles are to sharp or not tangent.
I worked on a fairly complex model with alot of small radi and curvature. I didn't want to loose the detail and took the highest possible resolution, keeping in mind the maximum mb for uploading. It was impossible to clean the file.You end up deleting triangels and at the end you're destroying the model. So I think if you use solid works just stick to the setting fine when you export your file.
Magics has a feature where you can reduce the triangles.



I also noticed that accutrans can't scale binaire stl.
It does scale asci stl. I make the stl 's in Solidworks.
Am I right or wrong?

Greetings AO
Re: Another inverted normals issue [message #3828 is a reply to message #3408 ] Tue, 07 April 2009 12:46 UTC Go to previous message
avatar PeterHermans  is currently offline PeterHermans
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@AO: I'm sorry I'm not familiar with Accutrans.

The prints arrived yesterday:
see this topic.

 
   
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