Author Topic: Filling a hollow form  (Read 228 times)

Davequa

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Filling a hollow form
« on: June 14, 2017, 11:10:42 AM »
I've spent quite some time producing a hollow hemisphere (wall thickness 2mm)  ???with an intricate pattern on the outer surface.  Now I want to fill the hemisphere so that it is essentially like a solid ball cut in half but retaining the pattern on the surface.  I've tried inserting a solid hemisphere of slightly smaller diameter into my hollow form and then combining the two but without a great deal of success as I keep getting gaps between the two.
Has anyone got any ideas please?NAV

rowiac

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Re: Filling a hollow form
« Reply #1 on: July 01, 2017, 01:59:16 AM »
Select the entire open edge of the hemisphere--move the pointer really close to the edge and double-click; this will select the entire edge for you (usually)--then use the Fill command (F key or Edit/Erase & Fill) to fill it.  You can also try the Analysis/Inspector tool and select the blue ball that appears to automatically fill the hole.

MagWeb

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Re: Filling a hollow form
« Reply #2 on: July 01, 2017, 06:50:13 AM »
Not sure about what you're trying to get

Most likely:
You've to flip the surface normals on the inside sphere (SelectAll of the inside shell and Edit/FlipNormals).
Now Combine both shells and PlaneCut.

Alternative: Use BooleanDifference to subtract the inside sphere from the outside sphere. This will result in an object with consistent inside-outside normals.

If you don't want a plane cut you've to SELECT the regions on the inside and outside shell and separate this selection. Use Bridge to connect inside and outside halves. Fill the remaining hole as rowiac suggested. Note, using EraseAndFill: Make sure to set it on a Flat Replace/FillType. SmoothMCV modifies the seam vertices too.
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Against that, if you want get rid of the inside shell (just a solid half of a sphere) you've to get rid of the inside and connecting surfaces and fill just the ouside boundary loop.
I'm just a user as you are. Being no Autodesk employee: I do not know where this road will lead to, nor do I claim to've all stuff got right.

locweb

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Re: Filling a hollow form
« Reply #3 on: July 05, 2017, 10:53:23 AM »
Hi, I have a full body  form scanned with Skanect, and it is not filled inside.
I would like to fill it inside for making solid slices with openscad.
I tried to use the make solid, or the select and F function as mentioned above, but it dont work.
When I check with a plane cut, the form is empty inside.
May I have some help ?

My english is basic, I am French.

Regards.

rowiac

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Re: Filling a hollow form
« Reply #4 on: July 05, 2017, 06:58:29 PM »
Can you upload the file?  Sometimes it can be tricky to fill an object, especially if it's a messy scan.

locweb

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Re: Filling a hollow form
« Reply #5 on: July 06, 2017, 12:47:16 AM »
Hi, I tryed to do this, but it is too much heavy (106672ko).

MagWeb

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Re: Filling a hollow form
« Reply #6 on: July 06, 2017, 05:58:36 AM »
MM does not support "Solids" in the CAD sense.

You've to understand that MM is working with surface meshes only.  This way to describe a 3D shape just deals with the outside skin (like a balloon) without any data inside. Meaning meshes are never "Solid". The surface owns an outside and an inside (rendered with a stripe pattern). Knowing what's inside and outside (and if the mesh is watertight) you can assume this space to be filled with something.

If you cut such a skin MM has to do two things:
1. splitt the skin to two pieces > this results in an open boundary on each piece
2. construct a surface to fill those open boundaries.

If PlaneCut fails to do the second step (fill) there's something wrong with your surface and its intersection with the cut plane. There maybe open boundaries hit by the cut plane, there maybe non-manifolds, zero area faces, self intersections....
Try to run ANALYSIS/Inspector to fix most of this mesh issues.



I'm just a user as you are. Being no Autodesk employee: I do not know where this road will lead to, nor do I claim to've all stuff got right.

locweb

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Re: Filling a hollow form
« Reply #7 on: July 14, 2017, 10:45:03 AM »
Hi, I tried to analysis, and accept the repairs.
After, I cut it in the middle and make erase et fill but it dont fill the inside structure.
I have no solution.
Regards

MagWeb

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Re: Filling a hollow form
« Reply #8 on: July 14, 2017, 02:33:39 PM »
Your PlaneCut result is just as expected. It's like the result you would get if you cut a real world hollow clay object with a wire.

If I understand right you want a cut result as if the object were not hollow?

If so  you've to get rid of internal stuff before doing the cut:
Go to SELECT, paint some tiny region orange and hit E to expand the selection to connected triangles (or via GUI: Do Modify/ExpandToConnected). Now the whole outer surface should be orange (= selected). If there's still some white outside surface visible do the same on it too.
Now hit I to invert the selection (For the selection is inside now you can't see the selection in case of an opaque shader any more). Now either hit X to Discard or Y to Separate internal stuff (Y creates a new object from the selection. Hide it via eye icon in the object browser).

Now do PlaneCut on your outer shell object and you should get what you want (if my assumption is right).
If there's still something inside it is somewhere connected to the outside shell. That's a bit more complicated. You'll need to sample several SelectVisibles before inverting to discard...


« Last Edit: July 14, 2017, 02:37:14 PM by MagWeb »
I'm just a user as you are. Being no Autodesk employee: I do not know where this road will lead to, nor do I claim to've all stuff got right.

locweb

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Re: Filling a hollow form
« Reply #9 on: July 17, 2017, 02:03:24 PM »
YESSS, it works now with your method.
Thanks a lot.