SubD Sharp Edge /Corner [seeking advice]

Hi everyone!

May I know what’s the best method to ensure that a sharp corner or edge in SubD will be exported properly? My program used is Sketchup, unfortunately the exported file got these random holes as seen in screenshot (highlighted in red). Is there something I need to do in Rhino to avoid this issue? Thanks!

Post a Rhino file containing your SubD.

Sample SubD Edge Export Issue.3dm (209.9 KB)

Here’s the Sample file. Thanks for checking!

I have yet to open your file in Sketchup but as a general advice I’d try to model with quads only.

Some quick adjustments to your shape result in much less surfaces. I attached the file. It could be improved. I think the shape could be modeled with less divisions, which would again reduce the number of quads and after conversion the number of surfaces.

Sample SubD Edge Export Issue.3dm (3.0 MB)

The attached file imports into Sketchup nicely. I exported the SubD without converting it into a Nurbs first.

In Sketchup I opened an empty file with metric units and imported the Sketchup file. I don’t know why but opening the file always seems to use imperial units. I believe the missing faces or flipped faces we see when opening the file in Sketchup is a tolerance issue.

SubD.skp (7.0 MB)

Here’s a closed SubD with a reduced division and a creased edge at the bottom. Note the file size…

closed_subd.skp (728.4 KB)

Imported into Sketchup and saved.

import.skp (741.8 KB)

Wow, thanks so much. Yeah the quads I still struggle with that, sometime I run out of connections and they become triangle. Thanks for this!

Nice, this is clean quality with really low file size. I’m interested about that crease function- can it be customized like how tight?

By the way, I was also did some trial and error with my file and specifically for sketchup use yesterday, and I found out that the lowest SubD edge that Sketchup can read without the artifacts is about 0.50mm per side. (measured when SubD toggle display is off). Anything lower than this, I’m getting those random holes.

This is related to my question above about adding crease, can I specify it to be not less certain value?
So far, I am doing it manually like moving the vertices as close as possible to edge.

Are you opening the file in Sketchup or importing? It might make a difference in some situations…

Also what’s your tolerance? I’m using standard 0.001 units absolute tolerance.

This sample SubD below has edges close together, less than 0.02 mm on one side and creased edges on the other side. It seems to open just fine in Sketchup 2017.

Subd_with_hole.3dm (250.4 KB)