Copying STL Files

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marcin_ose
Posts: 13
Joined: Wed Apr 29, 2015 9:20 pm

Copying STL Files

Postby marcin_ose » Fri Apr 22, 2016 5:46 am

Hello,

I have imported an STL file into FreeCAD, and am using the Draft Workbench. I am trying to copy and rotate the STL object.

This thread - viewtopic.php?f=3&t=15185&p=120865&hili ... ep#p120865 - shows that the STL must be converted to a solid first. I did Part ShapeFromMesh ->Refine shape -> Convert to solid.

This gave half decent results - but it appeared FreeCAD slowed down as the file had too many polygons even after refining the shape. Is there a good solution for smoothing out the entire shape to remove the polygons? Or is there any other STL to Solid converter that may work better?

Marcin



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ickby
Posts: 2959
Joined: Wed Oct 05, 2011 7:36 am

Re: Copying STL Files

Postby ickby » Fri Apr 22, 2016 6:02 am

Hello Marcin,
This thread - viewtopic.php?f=3&t=15185&p=120865&hilit=convert+stl+to+step#p120865 - shows that the STL must be converted to a solid first. I did Part ShapeFromMesh ->Refine shape -> Convert to solid.
Actually the draft tools work with meshes too, so for rotating/moving etc. you do not need to convert it to a shape. Just handle it like any other object in Draft workbench. The only thing I noticed during testing is that selecting "copy" in the move tool does not copy the mesh, seems like a bug. But you could easily Copy the mesh by hand (ctrl-c ctrl-v or menu->Edit->duplicate) and then move and rotate it
This gave half decent results - but it appeared FreeCAD slowed down as the file had too many polygons even after refining the shape. Is there a good solution for smoothing out the entire shape to remove the polygons? Or is there any other STL to Solid converter that may work better?
There is no good solution yet. The refine shape only handles polygons that are in the same plane, hence can be merged without the losing any detail. For curved areas this does not work.

Lately the Reverse Engineering workbench got some tools for approximating surfaces from point clouds, but I think this is still very rough and involves lot of manual python codeing. Maybe this evolves someday to some automatic feature matching tool.
marcin_ose
Posts: 13
Joined: Wed Apr 29, 2015 9:20 pm

Re: Copying STL Files

Postby marcin_ose » Sat Apr 23, 2016 12:04 am

Hello ickby,

Thank you. Yesterday the move and rotate tools were not working for me with an STL for some reason. I tried again today with the same STL - it works. I have noticed that starting a new document helps with a clean slate.

Converting STLs to solids works well in FreeCAD when the derivative solid is used in Boolean subtract. The subtraction results shows all the mesh lines, which disappear in shaded view. This means that STLs can be integrated well into a normal workflow.

A little searching on STL to Solid Conversion led back to FreeCAD - so FreeCAD is becoming the open standard for such conversion:)

Marcin
Founder, Open Source Ecology
http://opensourceecology.org/