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IK-Rig evenly curved following Mospline (bending)?
Posted: 27 May 2021 03:03 AM   [ Ignore ]  
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Hi Cineversity-Forum!

I have some trouble solving an issue with combining an IK-Rig with MoSpline.

My task: animating the installation of an insulation collar (for pipes).

In Pic 1 you see the plain model of the collar and the pipe in front view. My first approach was using spline-wrap combined with MoSpline for bending the model evenly curved around the pipe. This works fine but as you can see in Pic 2, there is some distortion going on on the mesh (screw holes). I’ve tried working with restriction/weighting but that doesn’t fix anything. My second approach was an IK-Rig (see Pic 4 - only a quick test) with weighting the screw holes and this works. With a little expresso I attached the IK-Goal to the end point of the MoSpline.

But the very last thing I was not able to solve (wether deep digging the whole net for a solution) is, how to bend the IK-Rig evenly curved following the curvature of the MoSpline (see Pic 4).

Any hints and tipps highly welcome! Or maybe there’s another way doing this (or something similar) with an other technique?

1000 thanks in advance for your help/feedback!

Sunny regards, Tom

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Posted: 27 May 2021 09:14 AM   [ Ignore ]   [ # 1 ]  
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Hi Tom,

Please have a look at the file below:
https://www.amazon.com/clouddrive/share/NTQu4aM475RZK1LI75CdjWr77ycZr22nMEH51WOMpc2

If you split the information, you can have a shape that is following the Spline Warp and compresses it [depending on the bounding box], but also the hard parts on the outside, which will not change the shape. Use the Offset slider of the Spline Wrap

Let me know if that works for you.

Cheers

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 27 May 2021 11:22 AM   [ Ignore ]   [ # 2 ]  
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Hi Dr. Sassi,


thanks for your reply! In your approach (if animated) the mesh “rolls” into the final form rather than bending. The collar is a flexible but massiv metal plate which can only be bended.

But I like the idea of dividing the geometry into the bended mesh and the “screw holes” placed separatly via the mograph cloner fix them to the surface. I’ll give it try!

Thank you and ‘till later, Tom

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Posted: 27 May 2021 12:19 PM   [ Ignore ]   [ # 3 ]  
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Thanks for the update, Tom.


Will this come closer?
https://www.amazon.com/clouddrive/share/IAJ4UeuzqJNyrArNkEOvziUK9pip7jX62FUX6bZJvdT

Cheers

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 27 May 2021 12:57 PM   [ Ignore ]   [ # 4 ]  
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Edit:—- just saw your second tipp ... my comment below is for your first tipp wink—-

Hi Dr. Sassi,

your tipp does (almost) the trick!

But now there’s another issue. As you can see in the attached pic there is a slight distortion of the meshs’ surface that leads to a missmatch between the collar and the attached screw hole that shouldn’t be there.

The construction (in real) is likely a flat metal plate (approx. 0.3 mm) which is punched in basic shape and the screw holes and other “pins” are bended at 90° +/-Y.

Is there a possibility to deactivate the stretching of the surface ... the bend-deformer f.e. has the checkbox “keep length”.

Sunny regards, Tom

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Posted: 27 May 2021 01:03 PM   [ Ignore ]   [ # 5 ]  
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Hola,

your second tipp look quite promising and fairly simple and the fact that you use the bend deformer seems to eliminate the new issue mentioned in my comment above (keep length).

I’ll keep you up to date!

Thank you very much for your effort!

Sunny regards,

Tom

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Posted: 27 May 2021 01:28 PM   [ Ignore ]   [ # 6 ]  
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Hi Tom,

Great, I had already typed a reply requesting the file (working from images while a scene file could give me so much more information, makes me always want to have the file here!), but I think we are so close that it is not needed anymore.

The part that is exactly in the center-line will be not stretched (or quizzed, for that matter).
So, if the outside needs to be stable (in length), then that center line needs to match the surface of the “metal-strip”.

Since edges can’t be bend, the part on the “metal-strip” defines the segment size of the band. Since this is any way in an “L” shape, I doubt that there will be a lot of shape-change happen.


If you have a file, I’m happy to look into it.

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004

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Posted: 27 May 2021 01:29 PM   [ Ignore ]   [ # 7 ]  
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Hi, it’s me again.

Sadly none of the approaches leads to the desired result. There is always a detail that doesn’t match (little gaps or offsets or mesh distortion).

My last idea is (also my least favourite): FK-rigging instead of IK. Maybe, instead of animating each joint angle manually, I can develop an expresso which controls the angle of each joint simultanously via user data. I think I’ll give it a try

Thanks and cheers,

Tom

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Posted: 27 May 2021 01:37 PM   [ Ignore ]   [ # 8 ]  
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Thanks, Tom,

The last posts obviously crossed.

What is not clear to me, how it is bending around the core. All at once, like one end is fixed and the other end is pulled around and tightened, or is it a progressively bend process like one end is fixed and a hand moves from start to finish to bend a straight metal around?

On the other hand, showing the whole process from start to finish takes a lot of time. If it would be an advertisement and time is critical, I would start bending it, cut, swap out the part, and show only the last bit tighten it while the swapped out part is optimized for the last position.

If you use FK and it an evenly bend, then you can select all joints and create a Selection Object. With that, you have all joints selected in an instant. With that, one entry in the Rotation field will rotate all.

Cheers

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004

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Posted: 27 May 2021 01:45 PM   [ Ignore ]   [ # 9 ]  
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Hi Dr. Sassi,

yep, our last posts overlapped wink

I’ve uploaded my “Testfile”. It contains my several approaches. I hope, it ain’t too confusing for you since it looks a bit messed up.

Link: http://www.octomber.de/cust/collar.c4d.zip

Also, here are some links to youtube which shows the collar and how it works.

https://www.youtube.com/watch?v=9j1okHhikT8

https://www.youtube.com/watch?v=lNOrSec3gpw (from 2:30)

To be honest - it drives me nuts wink There must be a way to solve this problem. Or maybe a bend-deformer on each “segment” (around 40 for a 90 mm pipe)?

Again - thank you very much for your effort!

Sunny regards, Tom

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Posted: 27 May 2021 01:50 PM   [ Ignore ]   [ # 10 ]  
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Tom, sorry, for security reasons I do not touch anything other cloud services than Dropbox, Amazon, Google, Apple, Adobe, or Wettransfer.

I can’t send you an PM, either you have disabled this, or the server has a hick up.

Thanks for the upload to Dropbox. Very much appreciated!

Just the main file, thanks.

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 27 May 2021 02:38 PM   [ Ignore ]   [ # 11 ]  
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Thank you very much for the file and the extra work, Tom.

This makes it so much clearer!

I share so many files here (besides other concerns) that I have to keep my system super safe to not spread weird stuff.

Please have a look at the file below. I hope that works for you:
https://www.amazon.com/clouddrive/share/vUns1kBaPkCPI5egLCgJVFXjQW96zL996EO4gCC7s93

The set up could be smaller, with a Modify Clones/Formula, but for now, this works.

My best wishes

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 27 May 2021 06:38 PM   [ Ignore ]   [ # 12 ]  
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P.S.: Here is a refined version.

https://www.amazon.com/clouddrive/share/KlDZ4KZX4fmYeRnNpyWRJiaFEC8fseu0gG91M6DjXvX

Where the tin is bending could have some extra points.
The tin would be pretty stable where it has these “ears” folded, so the bending will happen between those:
https://www.amazon.com/clouddrive/share/COSVRzD5owiIxDc9kF6rPBMnoVaqeYKGlLaRUxaWtGT

I have also added a Spy-camera so you can see how the area that caused trouble works now.

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Dr. Sassi V. Sassmannshausen Ph.D.
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Posted: 27 May 2021 09:42 PM   [ Ignore ]   [ # 13 ]  
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Good morning Dr. Sassi,

w-o-w ... that looks really promising! And it’s clearly a solution that would have never come to my mind! grin

I’ll adopt this and remodel the mesh and show you the result.

I’m so thankful for your help and effort - thumbs up!

Sunny regards, Tom

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Posted: 27 May 2021 09:59 PM   [ Ignore ]   [ # 14 ]  
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Good Morning, Tom.

Thank you very much for your feeback!

I look forward to your set up.

Here it is around 23:00h and I call it a day.

Yes, sunny regards from Southern California!

Stay safe!

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Dr. Sassi V. Sassmannshausen Ph.D.
Cinema 4D Mentor since 2004

Photography For C4D Artists: 200 Free Tutorials. Texture, Panorama, HDRI, Camera Projection, etc.
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Posted: 10 June 2021 07:49 AM   [ Ignore ]   [ # 15 ]  
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Hi Dr. Sassi,

sorry for the late feedback but the last week, several other projects needed attention wink

However ... I solved the issue with a combination of your approach and one of my several attempts.

I got the best result by combining the MoSpline-Rig with a correction deformer and some Expresso for animating. Here I use the correction deformer to manipulate the points of the screw holes so that the “bended” state matches the original form. This setup does the trick grin

I didn’t use your cloner setup since it is not rounded enough. But I definitively keep it in mind since we have a collar which has this form (seperate modules you can add or substract to match the pipes diameter).

It was a pleasure to chat with you and once again ... 1000 Thanks for your expert help!!!

Sunny regards from Germany (Ruhrgebiet) ... we finally have Southern Californian Weather :-D

Tom

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