"Puckering" of edge after thicken and toggle

[Michael_e]

Sorry for the simple questions, but I'm kind of baffled. After making some simple 2D surfaces, using thicken to get some depth and then toggling to a smooth surface, I invariably get at least one area on these simple models which gets a pucker in the edge or a hole in the interior. What am I doing to create these so that I can prevent this? Thanks!


Here's the pucker after toogling.


Here's the block mode model


Here you can see the added edge or line which was added during the thicken command.

[Nicholas North]

Michael,

The reason why you get puckering here is that your 2D surface, before running the thicken command, had some grips that were on top of each other, but not, as it appeared, a single grip.

I think you'll find that if you run tsWeld on the marked grips you'll get rid of the pucker:

The marked grips need to be welded.

split_verts.png (49.95 KiB) Viewed 1444 times

-- Nick

[Michael_e]

Thanks for the tip Nicholas. You're right about the two grips in one spot. The attached image shows the message in attempting to pick one of the points. The downside is that I can't seem to use the weld points command. The end result is that the image pops out of smooth mode, into block mode and then becomes unworkable. I'll attach a simple model in Rhino in case you'd like to have a go at it. Here's a question for you. Is there a way avoid this or to see this prior to going to smooth mode? Thanks again Nicholas.

[TomFinnigan]

Try welding before the thicken.

[Nicholas North]

Michael,

As Tom points out, your best option is to fix the problem before you run tsThicken.

Unfortunately, there's no automated way to detect that you need to weld -- both topologies are valid, so there's really nothing wrong. What you can do is try selecting grips, and if the Pick window comes up you know you have stacked points.

You could also smooth your surface before running tsThicken... you should be able to see that you don't get a totally smooth edge. This will point you to where to look for stacked points.

Hope that helps,
-- Nick

[Michael_e]

Thanks guy's. I tried both tips and they both worked well!

Michael

[Adam Helps]

So, the reason that you're switching to box mode when welding is that you have an interior non-manifold face. If you turn on edit mode/manipulator mode/the HUD/ctrl+space (I can't remember what we're calling it now), you'll see something like this:

The red lines are your warning that something strange is going on.

non-manifold-interior.PNG (33.77 KiB) Viewed 1368 times

Yours might be a little different, but there will be some kind of red line or point. So what do those red lines mean? It means that edge has *more than two* faces attached to it. How is that possible? Well, the third face is on the inside. I'll cut off the back of the cube so you can see what's happening:

There's an inside 'fin' face causing this surface to be non-manifold

non-manifold-cutaway.PNG (18.34 KiB) Viewed 1368 times

That interior face was created by the weld. Well, you could have avoided that by deleting those inner faces before welding, or you can fix it now by selecting that face and then deleting it.

One puzzle -- how do you select an interior face? The face selection doesn't let you 'click through', because there are other faces in the way. Here are some ways you could do it.

• Move the Rhino camera inside the object, which will let you see and delete the interior face.
• Switch to vertex-selection mode with 'A', and shift+click to select all the grips on the red edges. Now switch back to face mode with 'D'. If you did it right, the face will now be selected.
• Go to face mode with 'D' and click any face nearby that red edge. Push '=' or '+' (the 'grow selection' key), and it will select all nearby faces, including the interior one. Now use ctrl+click to unselect all the ones you don't want, and push Delete to remove the interior face.

Hope that helps .

[Michael_e]

That actually helps with more than just this last little problem. These little tidbits should be saved and added to the user manual, since they cover a lot of questions about things that aren't explained as deeply as this in the manual. The red dot/red line explanation is great, thanks Adam!