How to fix such holes?


I want to edit a STL file.
But after imporint the STL into SketchUp, there are hundreds of holes which looks like in the attached image.
I know that the hole can be fixed by draw lines, but is there any automatically method to fix all these holes?

I have tried to use the Merge Faces feature, but it throws following error:
16491 errors occurred. Please report the error and sample model to the author.

16491 - Face merge resulted in lost geometry!



When importing the STL, look under the Options button.
Try these settings:

Scale the model to correct size when you’re finished editing.


What @Geo is alluding to is the possibility that you have imported the STL at a scale that runs afoul of SketchUp’s nearby Vertex tolerance (.001"). If you import it at a larger scale you might avoid the issues in the first place, but you will also have less trouble repairing them. Then scale back down when finished.


From the image I would suggest to redraw the thing instead of trying to repair that mesh.


This really a clever idea.
There are only a few holes after I import STL with Meters scale.


Thanks for your detailed explain, really useful.


Good suggestion, but I’m unable to do this currently.
Will redraw this after having more SketchUp skills.


I don’t see the complexity of that model from the image, but I would bet that there are much more SketchUp skills involved in the repairing of such a mesh as in the remodeling.


I agree that the image looks like quite a spiderweb of strangely placed triangles, which leads one to wonder what sort of model it is a zoomed-in shot of and what created it. It seems dubious that the original was created using SketchUp, so maybe there is a way to make a cleaner version instead of wrestling with that mess! But we’d need to see the entire model to know.


Thanks, @slbaumgartner
I get the STL from (from which I can get customized iphone case online), but they do not support Chinese Fonts.
So I want to fix it in SketchUp and then I can carve Chinese characters on it.

I’m not sure how is it created.
The STL file is attached, I’ll be appreciated if you can have a look at this.
Thanks. (881.4 KB)


Wow! That file is really a mess! It contains a triangular mesh, but the triangulation is seemingly random and excessive. Even at meter scale, there are points that are fractions of a mm out of line, causing broken planes and zig-zags in what surely was meant to be a straight line or smooth curve. I suspect you will go out of your mind trying to repair it in SketchUp!

I’d use a 3D STL viewer to see what it was supposed to be (e.g. the attached screen shot) and start over if you want to work with it in SketchUp. There you can see that many of the tiny triangulated areas were meant to be four-sided facets.


The STL viewer is really helpful for fixing this mess.