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 Post subject: How to reduce number of triangles for STLs?
PostPosted: Tue Jul 02, 2013 5:11 am 
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Most of my multiple shell layer designs exceed 1000000 triangles, so they have to be split up into multiple files for shapeways. But, I have seen some people do amazing things with their triangle limit (TomZ managed to design a face turning starminx under 1000000 triangles while my starminxes require over 2 million)

I am looking for little tips and tricks to reduce triangles used, does anyone have suggestions?


(does anyone know why I keep getting logged out immediately after logging in? It is very annoying.)

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 Post subject: Re: How to reduce number of triangles for STLs?
PostPosted: Tue Jul 02, 2013 2:32 pm 
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I've used MeshLab's Quadric Edge Collapse Decimation to reduce triangle counts in STL files in the past. It has a pretty comprehensive selection of STL manipulation tools.

It is open source and available here : http://meshlab.sourceforge.net/

Steve


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 Post subject: Re: How to reduce number of triangles for STLs?
PostPosted: Tue Jul 02, 2013 4:01 pm 
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Steve wrote:
It is open source and available here : http://meshlab.sourceforge.net/

I've used it a lot too. Sometimes it works and sometimes it creates a lot of problems.

I think the best option is to control the resolution of the mesh when you export it from SolidWorks. See http://help.solidworks.com/2012/English/SolidWorks/sldworks/HIDD_STL.htm

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 Post subject: Re: How to reduce number of triangles for STLs?
PostPosted: Tue Jul 02, 2013 4:11 pm 
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rubikcollector123 wrote:
I am looking for little tips and tricks to reduce triangles used, does anyone have suggestions?
I use SolidWorks and I can adjust this parameter directly before savings. What software are you using to make your STL files? The default SolidWorks settings often produce over a million triangles for me too but you can easily cut this in half as that defaut resolution is well higher then the printing resolution. I wouldn't be surprised if you could cut it by an order of magnitude before you'd notice any effect on the print. I haven't been that extreem yet though, so don't try it without assuming some risk but a factor of 2 I'd feel very safe about.
rubikcollector123 wrote:
(does anyone know why I keep getting logged out immediately after logging in? It is very annoying.)
This happens to me all the time when I log in from work but not from home. I assume it has to do with the firewall at work not allowing cookies through or something like that.

Carl

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 Post subject: Re: How to reduce number of triangles for STLs?
PostPosted: Tue Jul 02, 2013 4:24 pm 
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wwwmwww wrote:
rubikcollector123 wrote:
(does anyone know why I keep getting logged out immediately after logging in? It is very annoying.)
This happens to me all the time when I log in from work but not from home. I assume it has to do with the firewall at work not allowing cookies through or something like that.
I've had similar problems when I upgraded to Win7 at work. I can't login at all (using Chrome), and SW can't help me. I can login with IE no problem :roll:

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 Post subject: Re: How to reduce number of triangles for STLs?
PostPosted: Wed Jul 31, 2013 2:40 am 
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Sorry for bumping, but I need some help.

The finished puzzle design is at 2.7 million polygons. In the STL options screen, there are 2 options that change the resolution. Angle and tolerance. What does each mean and what are the maximum values without affecting shapeways quality?

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 Post subject: Re: How to reduce number of triangles for STLs?
PostPosted: Wed Jul 31, 2013 11:45 am 
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rubikcollector123 wrote:
Sorry for bumping, but I need some help.

The finished puzzle design is at 2.7 million polygons. In the STL options screen, there are 2 options that change the resolution. Angle and tolerance. What does each mean and what are the maximum values without affecting shapeways quality?


When you design something in Solidworks the model is essentially "infinitely precise" but you can never achieve this level of precision by exporting to a triangle-based format like STL. The exported model will deviate from the Solidworks design and Solidworks has two measures of deviation. The "tolerance" measure is how far a face in the STL can deviate from a face in the source model. The "angle" measure is how far an edge or vertex can deviate in angle / "sharpness" from the source model.

Shapeways printers just aren't that precise. The print process has a maximum resolution of roughly 0.1 mm for faces and the "angle" resolution of the printer is even worse. You can allow both to deviate a lot and still have a perfect print.

Another thing to note is that Solidworks isn't "smart" about which pieces deviate more or less. You can have 60 small triangle pieces on the inside of the puzzle each using 10,000 triangles and the core for the puzzle only using 5,000 triangles. If you want to cut down the triangles in a smarter way you'll need to export each piece type and control the triangle count for each. Then put together all of those exported pieces into the final STL to upload. Remember, the smaller the piece, the fewer triangles it should need.

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