How to make sketchup read better STL


#1

Hi,

Frequently I download STL online and when I try to edit them in skecthup it’s a freaking painful process. When I import STL I always make sure to select the mesh option inside OPTIONS button. Take for example this file attached. tripod3Dv04_-_tripodPivotAssy-1_tripodPivot-1.STL (1.3 MB)

When I import it all the circles get converted into line segments. How can I make the concentric circles be treated as circles instead of line segments? I know sketchup always make circles become line segments but at least I can select the entire perimeter of a circle with a single click (and change radius, for example).

How can I make sketchup parse STL files better?


#2

Maybe you need to be importing better files. STL files are just not that great for importing into a surface modeler because it only uses triangles. Might be worth spending some time studying the STL file type.


#3

As far as I know, there are no circles in STL - only triangles. Converting a triangulated 3D mesh back into the original geometry that generated it is a feat that no computer application can handle automatically.

Anssi


#4

STL is not a file exchange format but contains dumb facetted meshes for outputting on a 3D printer… you can try to analyze/repair/optimize with Adesks Netfabb before importing into SU… but surely won’t result in something really workable anyhow.


#5

Thank you! I thought there was some feature or plugin in sketchup that would allow me to 'discover" or “map” geometries, like figurint it out where are circles, where they are not.


#6

I always run CleanUp3 on STL files that I import. Getting rid of all the extra lines helps a lot.


#7

Before positng I ran delet coplanar edges and will then have major edits to make it an acceptable model, does cleanup3 not do that ??


#8

CleanUp 2 could remove coplanar edges but the file of his that I worked on to split in half needed much more than simply cleaning coplanar edges.It was easier to start over than repair all the ■■■■ from the imported STL file.


#9

It is at least mathematically possible to determine whether a loop of edges are consistent as chords of a circle. But suppose software finds such a loop. How does one decide whether it was meant to represent a circle or just happens to satisfy the test? Any regular polygon (equilateral triangle, square, pentagon, …) will pass the test. But does that mean the polygon should have been a circle? There’s no way to tell!

An STL file contains a flat, unstructured list of independent triangles. There isn’t even anything telling you whether two triangles share a a vertex or an edge! My experience has been that STL is a “write-only” file format that is very sensitive to the design choices of the software that wrote the file. Many examples I have looked at appear to be the work of a very tiny drunken hyperactive spider! As @DaveR has noted here and elsewhere, it is usually far less work to look at the STL using an STL viewer and redraw the shape in SketchUp without importing the file.


#10

I have run test cases wherein it is confirms in spades the STL does not carry topographical info. so one is using a bad file as a reference to create another one. If at all possible you want to use a well established format that is consistent and gives you the same answer when you do multiple imports and exports or at least you only do 1 export to use for 3d print?
Checking cleanup3 did not appear to show any better than delete coplanar edges but it will take much more effort to finish test.


#11

I was just replying to the OP… General rule of thumb for working with STL files…


#12

Description of the year! :smile::smiley: :smiley:


#13

Which STL importer are you using? The SketchUp STL Extension has no “mesh” option.


#14

I am using the IMPORT button inside FILE menu. I sorry, I wanted to mean MERGE COPLANAR FACES. I


#15

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