Merging curves preserving each topography

I 3D scanned(.stl file) the pipe which is cut into two different pieces, and by using the contour method provided in grasshopper the closed curves at every interval of 1mm to the longitudinal direction were acquired.

I’m aiming to merge the two closed curves preserving the topography. However, during the cut, the pipe was little deformed as depicted in the picture. The inner and outer curves should be connected and the overall shape should be remained closed to circle.

Anyone who has the idea is welcome.

Hi - it’s not clear to me what you are trying to do here.
As you say, the pipe was deformed. If you need those parts to get back together, they will have to be deformed again and you won’t be able to “preserve the topography” of the current state.

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To be specific, the one that i want to preserve is the thickness of the pipe. I agree that I cannot preserve the exact topography. I’m just searching for a good idea. For example, some software provides non-rigid registration of the deformed 3D scan and the one that is not deformed. I think the tool is similar to what I’m trying to do but the software like Artec studio is quite expensive for me to use. Thank you for the reply!

Thanks for that additional information. The exact application is still a bit unclear to me and I don’t know if you have any original information about that specific pipe (like OD and WT).

It looks like that the wall thickness of the pipe is still rather regular and you could probably get Rhino to create new circles through points extracted from the halves. I suspect that in many cases, that would give a good-enough result. If you are trying to work out corrosion at specific locations and very tight tolerances, that would probably not be a good enough workflow.

Can you post the original stl file?

Here I attach the files. The pipe was segmented into four parts. And first I attach the two segments and the original shape of the pipe which is only scanned outer shape and a little of inner shape.

I found out that my file is too big to upload here. It’s over 100MB per each scan.

Hi - if you also have a scan of the original pipe and a little of the inner shape, it should be relatively simple to recreate an “idealized” pipe - i.e. two mathematically correct cylinders. The question remains if that is what you want to get out of that.

Can you specify the “two mathematically correct cylinders”? Like the technique I should use in Rhinoceros to recreate the pipe? This is my last question. Thanks!

Hi - there are several ways to create a pipe object in Rhino. If you have the center line, the Pipe command will do this in one step. Making two cylinders inside of one another and making end caps is another option. From your scan, you could extract points from a section and build a circle that has best fit through all points. Extrude the circle to make a cylinder.

If something is not clear, you are welcome to ask more questions!