STL creating faceted surfaces


#1

I am using the .STL Plugin. When I create the STL file all the curved surfaces are really faceted. Is there a way to control the number of facets or make the surfaces smoother when exporting?

Thanks,


#2

The STL file format doesn’t support any information about smoothing. It’s just triangles. And as for the number of facets - it exports only what you have in SketchUp.


#3

I wonder if 3D printing is finally what will force someone to develop an user-friendly 3D modeling application using true solids and NURBS geometry. Personally I would wish for it to be called SketchUp. Anyone toying with 3D printing starts with something like a coffee mug, and getting one with a faceted surface will be a disappointment. Surface quality should be determined by the printer’s capabilities, not by the modelling software.

Anssi


#4

Is there a setting in Sketchup that will allow smoother surfaces when it is exported?


#5

Afraid not, SketchUp doesn’t perform any smoothing - it exports only exactly what you modelled.
Though you might have some luck with Dale Martens Artisan extensions which allows you to subdivide and smooth geometry: http://extensions.sketchup.com/en/content/artisan-organic-toolset


#6

And what an outstanding extension that is!

Being myself a prototype builder, I sometimes find it annoying that a surface I build smooth as a baby’s face is seen by the 3D-printer as a triangle-jungle as a cobweb made by a spider on LSD. Or my triangle array is quite well ordered and smooth looking, but the printer sees a freshly hoed field.

Sorry for my lack of experience, but can anything be done, at least to avoid the serrated effect? I

A test I made was to send the block below to Shapeways to see what came out:

The block on the right is for illustration only, the edges are in order : hard, hidden, soft, soft+smooth. Shapeways interpreted all of them as hard. I may be re-inventing the wheel but it looks like there is a difference between a visual-only model and a printable one. What can I do, multiply the number of triangles so facets and serrations will be less prominent? What do the Experten advise?

Thank you very much,
Miguel


#7

Correct. Soft and smoothed edges in SketchUp are visual properties only. When modeling for 3D printing, it may be desirable to not use soft and smooth edges so you can see exactly what will be printed. If you need smoother arcs and curves, you need to increase the segments during creation.


#8

Thanks Jim, I was surprised at first, but it’s only a matter of designing taking that into consideration. Certainly not a SU-specific problem.