Author Topic: Sharp Inside Corner Cleanup  (Read 634 times)

cadman777

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Sharp Inside Corner Cleanup
« on: January 04, 2018, 06:51:00 PM »
Hi,
I'm new to MM & this forum.
Been trying to learn MM, which is an excellent program!
One thing I keep having difficulty with is cleaning-up a sharp edge created by flat surfaces that connecting together.
Even more difficult is cleaning up an inside corner where 3 flat surfaces connect.
Is there a simple way to do this?
I couldn't find a thread on this, so if there is one, could someone please link me to it?
Thanx ... Chris

MagWeb

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Re: Sharp Inside Corner Cleanup
« Reply #1 on: January 06, 2018, 07:27:06 AM »
Hi Chris,

reconstructing sharp edges is one of the hardest tasks dealing with arbitrary meshes.
MM doesn't come with a "hard edge reconstruction" tool but there are several workflows managing such a task.

If it comes to edges where plane neighbour surfaces meet this is my favourite workflow:
1. SELECT regions where you are pretty sure that they are actually plane;
2. Run SELECT/Edit/FitPrimitives. Set the tool to create a plane surface on each selection (for parameters see attached image). Drag the white cubes in the widgets' enters to sale up the planes until they intersect.
3. Activate all resulting planes and combine them to one object
4. In ObjectBrowser click its magnet icon to set it as a target object (Note: By default a target will be rendered transparent. You may change this (as done here) via menu:View/TransparantTarget). Activate your source object and SELECT the ugly edge regions.
5. Run SELECT/Edit/AttractToTarget with the shown parameters and Accept
6. You'll get nice edges.

You can do the same on outside edges.....
« Last Edit: January 06, 2018, 08:00:44 AM 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.

cadman777

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Re: Sharp Inside Corner Cleanup
« Reply #2 on: January 06, 2018, 07:27:34 PM »
Hi MagWeb,

Thank you for your speedy reply.
This is an excellent work-flow.
Thanx!

Now for a related question:
How would you fix the inside corner while also maintaining the inner fillets between adjoining surfaces as seen in the original scan data?

Cheers ...

MagWeb

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Re: Sharp Inside Corner Cleanup
« Reply #3 on: January 07, 2018, 06:49:01 AM »
If you like to maintain some original surface (e.g. some fillets) you simply have to exclude those regions from the selection in step 4.

Maybe better to reconstruct the fillets from the upper result?:
1. Generate a FaceGroup for each adjoining plane surface
2. Create a pivot (CoordinateFrame set to GeometryFrame and PlacementMode at SnapToGroupCenter) on each adjoining surface
3. Run EDIT/PlaneCut with CutType set to SliceGroups and click on a pivot to make the cutting plane snap to this orientation
4. Enable snapping in the widget (the little "S" circle has to be green and the "A" circle has to be grey - click on the circles if not). Now move the cutting plane dragging the arrow perpendicular to the surface (Using UP and DOWN keys on your keyboard while dragging allow to set the snapping increments) to the fillet's radius.
5/6. Repeat step 3 and 4 on the other pivots.
7. SELECT the new created face groups , merge them to a single group (result should look like left image) and select it again
Optional: Refine this selection via SELECT/Edit/Remesh to a higher Density. Make sure to set FixedBoundary in BoundaryMode to avoid cracks in the mesh.
8. Run SELECT/Deform/Smooth. Play with the tool's settings to get the desired rounding. Keep an eye on ConstraintRings. Depending on the region's density this might have to be set to a lower value than default 3.
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.

cadman777

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Re: Sharp Inside Corner Cleanup
« Reply #4 on: January 07, 2018, 06:27:31 PM »
Hi Mag,

Thanx for the workflow.

So let me clarify.
You're basically replacing the mesh face with planes, then backing-up the new plane to the tangency of the fillets, then joining the of the edges opposing places with a smoothing operation, right?

Much obliged for your generosity in sharing your knowledge!

Cheers ...
« Last Edit: January 07, 2018, 06:32:45 PM by cadman777 »

MagWeb

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Re: Sharp Inside Corner Cleanup
« Reply #5 on: January 08, 2018, 12:06:21 PM »
I wouldn't call the flattening steps "replacing the mesh with planes" but "projecting existing surfaces to ideal planes". The inserted plane primitives are just projection targets.
The PlaneCuts (SliceGroups) construct parallel "edgeloops" and finally the "fillet region". The "fillet region's" hard edge is smoothed to get a round corner finally.
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.

cadman777

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Re: Sharp Inside Corner Cleanup
« Reply #6 on: January 08, 2018, 01:46:00 PM »
OK, I get it.
Again, thanx!

cadman777

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Re: Sharp Inside Corner Cleanup
« Reply #7 on: January 11, 2018, 09:47:41 AM »
OK, I tried this and it works great!
Unfortunately, it was too much flatening for the rest of the mesh, so it looked like a tumor on the model!
What I need is a nice hole-fill that fits the hole filling patch to the contours of the surfaces instead of fitting the patch to the edges of the hole. What I want to do is pick the clean areas of a surface, enough so the selection describes the surface contour, and then expect the hole fill will continue those faces up to the edges of the hole and fill the hole based on all the surrounding face contours. Currently all my hole fills don't go well. They get either a slight bubble, or the edges don't join well due to the scan bumpiness. Then trying to clean-up inside corners or fill voids is near impossible. How do you handle that? Is this a subject that I need to post under a new topic?
« Last Edit: January 11, 2018, 01:18:22 PM by cadman777 »

MagWeb

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Re: Sharp Inside Corner Cleanup
« Reply #8 on: January 11, 2018, 03:50:41 PM »
If the result is to clean compared to the rest of the mesh:
Instead of using the inserted primitive planes you could extract plane areas of the existing mesh (SELECT/Edit/Extract + Separate), align this surface instead of the planes above...

As an alternative to the workflow above and if you want less perfection you might prefer a manual way:
SCULPT and its Pinch brush: Set its Depth to a positive value to work on inside corners, to negative on outside corners
---------
@ hole filling
As you describe slight bubbles: Guess you already tried FillType "Smooth" in Inspector?
You might try this instead: In SELECT select the boundary faces of an open boundary (double clicking the hole's seam) and run Edit/EraseAndFill with FillType "SmoothMVC". This is like smooth filling in Inspector but gives more control. Try Scale and Bulge sliders to avoid "bubbles" or bumps.
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.

cadman777

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Re: Sharp Inside Corner Cleanup
« Reply #9 on: January 11, 2018, 07:05:04 PM »
Hi Mag,

Thanx for your input.

Yeah, I already tried all of the things you suggested. I spent about 2 weeks of days learning the various MM commands and seeing if they can do stuff that I need, in order to do RE work and accurately prep scans for 3D printing. It just seems to me the MM tools don't have that "industrial" power that I need. I really dumped a lotta time into learning MM. Was hoping for more power after learning all the basic commands ... that is, more advanced "surface" editing.

Kind'a reminds me of how Autodesk 'plays' in the market place: Maybe that's what Autodesk wants for MM ... a simple program to gets people attracted to mesh editing, so when they get to a certain level of mesh editing and "need more", they'll WANT to pay for a Fusion 360 or MudBox license. Well, that ain't me.

I even tried learning MesLab, but it's REAL hard for me to learn. Too many commands scattered all over the place, and no real work-flows to get anywhere w/out going nutz with work-arounds. Plus, it crashes all the time. I've found this to be true of the Public License softwares, and often wonder if this is a deliberate market strategy by the big corporations that fund development and sales of the expensive licensed programs??

Incidentally, I've used Rhino3D for nearly 2 decades, and have been waiting for them to get their mesh editing and digitizer input up to an industrial level, but have been totally disappointed. Rhino3D is just so primitive when it comes to mesh editing and CMM input!

After the big disappointment with Rhino, and knowing I could never afford or justify buying a license of Design-X or PolyWorks, I turned to MM to see if it is any better than Rhino3D. All the rave reviews convinced me to give it a try (after also looking at many other programs). Turns-out MM is WAY better at mesh editing than Rhino3D. But now I'm discovering that MM still lacks the functions needed to get the model "trued-up" for streamlined RE work or accurate 3D printing. MM got me about 1/3 of the way to where I want to go, whereas Rhino didn't hardly get me started. But I'm still not "seeing any light at the end of the tunnel".

Maybe I'm mistaken, but this is how it seems to me after many hours of learning MM and other programs. Incidentally, I use Inventor as my main CAD program. My ultimate goal was to combine some sort of RE work of scanned meshes with Inventor. Rhino was my first choice due to it being in my 'toolbox' already. However, it looks like you gotta "pay big to play big". Oh well, that ain't me!

Thanx for helping.

If you have any other suggestions on how to accomplish my goals without 'breaking the bank', I'd be very grateful to hear them.

Cheers ...
« Last Edit: January 11, 2018, 09:42:27 PM by cadman777 »

3DWP

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Re: Sharp Inside Corner Cleanup
« Reply #10 on: February 10, 2018, 06:30:45 AM »
Hello,

If you are looking at RE and editing meshes I hear lots of good things about Spaceclaim - with the ''STL Prep'' module I think it's about one third the price of Design X.

I have tested it a few times and for instance fixing STL meshes that I couldn't really fix anywhere else were fixed fast and great. I tried a shrinkwrap/make solid tool. But there are also CAD design and RE tools of course.