Sketchup Solid Inspector VS Netfabb Basic: Which to Trust?

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Sketchup Solid Inspector VS Netfabb Basic: Which to Trust?

Postby SKYWAYS128 » Wed Dec 17, 2014 12:31 pm

I've been importing and exporting stl files between Sketchup and ZBrush for a few days now, and I noticed that whenever I export the file back to Sketchup, Solid Inspector (a plugin that checks to see if a model is solid or "water tight") always discovers triangles without faces.

The only things I've done to the model after importing to ZB was simply to make it into a polymesh, Dynamesh to 256 resolution, and then decimate it back to around 20k poly's. I was just testing how many polys Sketchup can handle before it noticeably slows down.

After hopelessly trying to solidify the file with Sketchup plugins, I repaired the stl file in Netfabb Basic (free version), and the status box says there are no holes. But when I import it back to Sketchup, Solid Inspector still finds numerous triangular holes.

I'm beginning to suspect that Sketchup actually failed to generate those faces on the triangles, since the holes didn't appear in Netfabb or ZBrush.

I guess what I'm trying to say is, if Netfabb says there are no holes in the model, should I take it's word for it over Solid Inspector's?

Thanks for any advice.
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby Box » Wed Dec 17, 2014 12:38 pm

It sounds like you've worked out the answer.
If you are importing small models into SU then it's most likely not forming the little faces.
If you import at a larger scale it will probably remain a solid.
So I wouldn't say Solid Inspector is failing, you are running up against the tiny face problem inherent in Sketchup.
If the vertices that make the faces are around 1mm apart SU can see them as the same point and fail to form the faces.
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby SKYWAYS128 » Wed Dec 17, 2014 1:33 pm

Box wrote:It sounds like you've worked out the answer.
If you are importing small models into SU then it's most likely not forming the little faces.
If you import at a larger scale it will probably remain a solid.
So I wouldn't say Solid Inspector is failing, you are running up against the tiny face problem inherent in Sketchup.
If the vertices that make the faces are around 1mm apart SU can see them as the same point and fail to form the faces.


Hi, Box!

Yeah, that does seem like the case. I remember running into a similar problem with soap skin bubble, before I realized I had to magnify the size of the model up to 100 times for Sketchup to form skins properly. That would explain why Sketchup refused to repair a good number of the small triangles.

The space between some of those triangle holes are as small as 0.1mm! And that's AFTER I resized the model to almost 1000mm! :shock:

Well, I'm just glad the model's probably watertight after all.
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby d12dozr » Wed Dec 17, 2014 2:43 pm

If you want the imported model to be watertight, you can set the STL plugin import units to Meters before importing, and then it should work.

And yes, if Netfabb says the model is watertight, you can be assured that it is! :thumb:
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby SKYWAYS128 » Wed Dec 17, 2014 3:05 pm

d12dozr wrote:If you want the imported model to be watertight, you can set the STL plugin import units to Meters before importing, and then it should work.

And yes, if Netfabb says the model is watertight, you can be assured that it is! :thumb:


Thanks for the pointers, d12dozr!

There's a dialog box that appears when I import an STL file, which asks if I want to set the units in inches, millimeters, etc, but how to I convert back to millimeters once I'm done checking with solid inspector? I'll need to convert the model back to it's intended measurements for 3d printing.
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby Box » Wed Dec 17, 2014 3:10 pm

Small faces can exist in SU it just has problems forming them.
Import larger to check then you can resize it as necessary and export again.
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby d12dozr » Wed Dec 17, 2014 3:34 pm

SKYWAYS128 wrote: how to I convert back to millimeters once I'm done checking with solid inspector? I'll need to convert the model back to it's intended measurements for 3d printing.

Simplest is to just work in meters, and then set the units to meters when exporting the STL and the scale will remain correct :)
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby SKYWAYS128 » Wed Dec 17, 2014 3:59 pm

So, I work in meters and export in mm? Got it.

Thanks again for all the great help, guys! :thumb: :thumb: :thumb:
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby d12dozr » Wed Dec 17, 2014 5:43 pm

SKYWAYS128 wrote:So, I work in meters and export in mm? Got it.

Nope :!:

Import as meters, work in meters, export in meters...do everything with Sketchup using meters. When you open the model in another app for 3D printing, THEN you import as mm and the scale will be correct.
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Re: Sketchup Solid Inspector VS Netfabb Basic: Which to Trus

Postby SKYWAYS128 » Thu Dec 18, 2014 12:30 am

d12dozr wrote:
SKYWAYS128 wrote:So, I work in meters and export in mm? Got it.

Nope :!:

Import as meters, work in meters, export in meters...do everything with Sketchup using meters. When you open the model in another app for 3D printing, THEN you import as mm and the scale will be correct.


Whoops! :oops: Thanks for the clarification!
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