Full Version: V4 beta Oct-17-2018 available now - SubD to NURBS conversion

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Maybe he has a lower mesh angle setting on the one computer.???

Just a thought......

On another note, something i just noticed, but maybe it is normal, as i get the same thing in v3....

I think you called it "z fighting"...

So like in the 3d viewport, at some distance you can see edges if surfaces which are UNDER a surface, if you zoom in closer, the underlying edge goes away and you see the surface only.....

However, in the 2d views, the edge stays visible, even as close as you can get.... this didnt seem right, or at least i hadnt noticed it before.....

Comment?

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Hi Burr, yeah unfortunately that's a pretty hard type of display artifact to avoid completely especially in a 3D perspective view. In a perspective view the distribution of depth values isn't linear like it is in a 2D viewport. It makes it difficult to deal with things drawn in separate passes and with somewhat different draw mechanisms like shaded surfaces vs curve drawing.

- Michael

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Hi Michael,
Maybe you misunderstood?

My 3d viewport works ok... it is the 2d viewports that wont elimimate the underlying edge when zooming in....

Did you get that part?

Thanks for the responses...

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Hi Burr, sorry no I didn't understand correctly. So it sounds like you're talking about this kind of display artifact discussed here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4987.2

A 3D perspective viewport has a little different kind of depth behavior than a 2D one, so it's not too surprising that you would see slightly different behavior with depth sensitive operations between them.

I do have some ideas that I'd like to try to experiment with for reducing that type of display artifact in the future.

- Michael

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Thanks Michael!

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Some results from saving cubes in MoI as .obj, and applying create subD:

Attached are the solid models 4Box01.3dm and 4Box02.3dm, created in MoI, derived from the Box tool, which appear to be identical, but are not. Saving as .obj files and then using create SubD results in different SubD models. There are at least two additional permutation models, which result in different .obj and subD results. Saving some .3dm and reloading them, then saving to .obj and applying SubD may result in different results than the pre-saved .3dm to .obj save.

Creating 4Box02.3dm:
1. Create a box.
2. Use circular array to create 4 boxes touching by their edges.
3. Change color and Separate the inner 4 faces, leaving the outer 20 faces joined into 4 open cubes.
4. Select the 4 open cubes, excluding selection of the inner 4 faces, and join.
5. Select the 20 face outer joined surface, then select the inner 4 faces one by one. (they can be selected in different orders), and join to form the 24 face solid.
6. Save as .obj.
7. Use create SubD on the .obj file to yield 2 or 3 subD objects.

Creating 4Box01.3dm:
1. Create a box.
2. Use circular array, or copy to create 4 boxes touching by their edges.
3. (May change color of the 4 inner faces.) Select all 4 cubes and Separate.
4. Select the 20 outer faces and join to a joined surface.
5. Select the outer 20 face joined surface, then select each of the 4 inner faces, one by one, and join to one solid. (Note that selecting the 4 inner faces by their color, or by their name, does not give the same result.)
6. Save as .obj.
7. Use create SubD on the .obj file to yield 1 subD object.

Using meshlab, it turns out that the 4Box solids are not manifolds, and that they have different non-manifold edges. The meshlab command:
Filters/ Cleaning&Repairing/ Remove Faces from non manifold edges,
shows the difference between the two .obj solids.

(Three boxes may be arranged around a central triangle with comparable results.)
- Brian
Deleted this old attachment, for space.

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Hi Brian, thanks for testing this. The problem is that in both 4Box01.3dm and 4Box02.3dm the objects are not clean solids because more than 2 surfaces are coincident at these edges:



Having that type of geometry as one single object will cause various kinds of inconsistent behavior not just for .obj conversion but also for various other operations as well.

That should be separated out into 4 separate independent objects instead of being just one single object, that should then give a lot more consistent results.

I can understand that it is objectionable that MoI reports the object type here as "solid" but unfortunately it isn't really feasible for MoI to do an extensive self intersection test as part of the properties panel display. That's because such a test can end up being very time consuming especially on larger models and it would not be very good for everything to pause for say 10 seconds or so with every selection.

- Michael

Image Attachments:
brian_non_manifold.jpg 

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Thank you Michael.
I'm going to move on to other projects now :-)
- Brian

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Hey Michael,
THanks for the update. I'm getting an "Invalid Error" message when I try to download.


-Alan

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Hi Alan, please e-mail me your license key at moi@moi3d.com so I can try to see what the problem is.

You can also get your license key e-mailed to you from this page here: http://moi3d.com/reinstall.htm .

- Michael

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Thread Split: This post has been moved here

Thread Split: This post has been moved here

Hi Vladimir, I've split off your question to its own thread here:
http://moi3d.com/forum/messages.php?webtag=MOI&msg=9154.1

- Michael

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Hi Michael.
> What operating system are you running?

Windows 7 64bit.
Vladimir.

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Hi Vladimir, I will reply in the other thread I split your topic off to, over here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=9154.1

- Michael

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Was playing around with the Boolean Merge tool and may have found a bug whereby one of the newly 'Merged' parts instantly disappears after creation. If not a bug, then why does that particular part go missing?

Here's a very short video I made of what happens.

https://vimeo.com/304006382


Martin.

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Hi Martin, that's actually how boolean merge is meant to work when open surfaces are involved. When there are open surfaces it will try to extract all closed volumes it can and remove the exterior surfaces, there's another example here: http://moi3d.com/3.0/docs/moi_command_reference7.htm#booleanmerge , see the one labeled "Boolean Merge can also be used to extract a common solid volume from a set of intersecting surfaces:".

> If not a bug, then why does that particular part go missing?

It's because it's an open surface and not a closed volume after everything has been intersected and merged.

- Michael

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Thanks for explaining that for me, Michael.

I didn't need that particular bit, but could you tell me if there's a way to retain those parts in case you wanted to use them for something later, please?

Cheers, Martin.

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Hi Martin, one way to keep it is after you see that it's gone use undo to go back a step so it will reappear then select it and use Cmd+C to copy it to the clipboard, then redo then Cmd+V paste. That's kind of a general purpose way to keep something that was removed by any command.

Or another possibility is to use boolean difference with that surface as the cutting object, there is a "Keep objects" checkbox in the command options that you can use for boolean difference where it won't remove the cutting object.

By the way I still have it on my list to investigate the file dialog thing you wrote about way further up in this thread I just haven't had a chance to do the testing for it quite yet.

- Michael

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Hi Michael,

i like to ask if you already found a solution for creases with the subd to NURBS feature,
or is it something you thinking about, once MoI v4 is released?

Best regards
Stefan

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