keppel opened this issue on Jul 29, 2023 ยท 8 posts
keppel posted Sat, 29 July 2023 at 3:36 AM
Does anyone have a suggestion on how to unroll a cylinder to a plane?
Context:
I have a photogrammetry model of a column with sculpted details that I want to unroll into a flat plane turning it into a frieze.
Mesh density is too high to do it manually.
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Lobo3433 posted Sat, 29 July 2023 at 8:49 AM Forum Moderator
Hello keppel
I can not find any thing close to what you want to do unless it is like rigging the cylinder to create an animation of it unrolling and all other similar finds concern UV mapping with I understand is not what you want. I will keep searching to see if I can find a solution to your question
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keppel posted Sat, 29 July 2023 at 10:06 AM
Appreciate the effort Lobo. I've done a pretty exhaustive search myself with no success.
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LuxXeon posted Sat, 29 July 2023 at 11:46 AM
Is there any way you can project the details to a vector displacement map or even a normal map on a much more lower density column like the cylinder in your example, then manually unwrap that?
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Warlock279 posted Sat, 29 July 2023 at 11:17 PM
Yup, what @LuxXeon said is probably the logical way of doing it. Bake/project the high poly to a displacement, apply it to a lower poly mesh, and unroll that mesh.
Without seeing the mesh [how much relief there is in the carving/sculpting], I wouldn't discount pure brute force. Volume/area selection tools, and going in small increments, it'll take you a bit of time but its not difficult, just tedious [you don't have to be perfect, the process is usually somewhat forgiving]. In the days before modern UV unwrapping tools that was sometimes the only way to do it!
Or as @Lobo3433 mentions, you could just rig it. A ring of bones, rotate them until they're straight, and save the transformed mesh.
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keppel posted Sun, 30 July 2023 at 12:23 AM
Thanks for the tips, they have given me some ideas to work with. I can picture rigging the mesh like a tail could work. Whilst reading your replies it occurred to me that I might be able to do a series of front ortho renders of the column. Render, rotate, render, rotate etc, Then take the image sequence and stitch them into one image and use that image to generate, normal and displacement maps for a new mesh. Thanks again for the help.
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Warlock279 posted Sun, 30 July 2023 at 10:34 AM
keppel posted at 12:23 AM Sun, 30 July 2023 - #4471479
Ooof! Good grief don't do that! Please! I know I said not to discount brute force, but that's not what I meant!Whilst reading your replies it occurred to me that I might be able to do a series of front ortho renders of the column. Render, rotate, render, rotate etc, Then take the image sequence and stitch them into one image and use that image to generate, normal and displacement maps for a new mesh. Thanks again for the help.
You're far better off baking a projection from one mesh to another mesh, even if you use a basic 24 sided cylinder, than you would be trying to stitch a series of images together. You wouldn't necessarily even need to "flatten" the cylinder after that. UV map it, which will given you a flattened/"unrolled" image when you bake it. Then create a flat plane, that shares the same UV space/image.
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cjd posted Wed, 02 August 2023 at 10:10 PM
CloudCompare has a tool to unroll a cylinder. Some functions in Cloud Compare will only work on point clouds, I don't recall if this one is limited to point clouds only or if it will work on a mesh