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I am new to blender, and I am looking to inflate the geometry of an artery like a balloon.

inflation

I have used the shrink/fatten tool and it produces the outcome I desired except for the inlet and outlets. I want the artery model to be considered a shell, and if we imagine that the inlet and all the outlets are fixed, I would like the shell to simply expand a percentage, maintaining the original positions of the inlet and outlets.

problem

I hope the images help to display my problem, yet if I haven't been very clear, I will try to explain better. Thank you in advance for the help.

Okra
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  • Do you want the size of the inlets and outlets to be fixed, or just their location? – Robin Betts Sep 30 '21 at 10:41
  • Hey, thank you for answering. The area of the inlet and outlets should increase just like the shell, but I don't want their position to change. Hopefully this makes it more clear. – Okra Sep 30 '21 at 11:01
  • One approach is to use bones to animate the inflation of the arteries. See this answer - https://blender.stackexchange.com/questions/70151/how-to-animate-a-beating-heart which illustrates how to do this to animate a beating heart. – Ed Tate Oct 04 '21 at 02:39

1 Answers1

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You can give the object a Displace modifier. along Normals, and animate the strength:

enter image description here

This can be modulated by aiming it at a vertex-group, to vary the inflation along the vessels, or combined with a Solidify.. there are various possible elaborations.

Here, a Corrective Smooth has been added at the bottom of the stack, to iron out intersections.

enter image description here

You may need to improve your topology, but this should be OK.

Robin Betts
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  • Hello, thank you very much for your reply. The animation you sent is exactly the effect I am looking for. Since I am new to blender, could you please provide me a tutorial on how to perform this? Also, this geometry was obtained through a 2D to 3D program, so I do not think I can improve its topology. Would that be problematic to achieve the desired result? – Okra Sep 30 '21 at 12:26
  • Update: The result is the exact same as the one I already have, since the geometry you used does not have a surface in the inlet and outlets... is there a way to obtain your results when there are surfaces in the inlet and outlets? – Okra Sep 30 '21 at 12:31
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    @Okra yes, you can get solid-walled tubes by adding a Solidify modifier after the Displace . If you want the walls to get thinner as the vessel expands, you would have to animate that, too, or drive it with the displacement. A step-by-step of key-framing is not hard, but a little bit time-consuming to describe in an answer. I'll get to it, but can't, right away. – Robin Betts Sep 30 '21 at 12:43
  • Hello Robin, thank you again for all the help. I do not wish to vary the thickness, nor do I want to animate the final result. My goal is to simply create a new geometry based on the original one to use in numerical simulations in other programs. I look forward to hear from you when you have the chance. – Okra Sep 30 '21 at 12:48
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    Ahh.. good. Do you want solid-walled tubes, or the ends of the vessels to be capped (blocked)? – Robin Betts Sep 30 '21 at 13:25
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    Hello, the geometry is meant to be considered the fluid inside the artery, and therefore the geometry should be closed (the ends should be capped). – Okra Sep 30 '21 at 13:42
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    @Okra Hi, sorry for the delay. the best I can think of for a 1-off, without messing with normals, etc., is to split the caps off, Shrink/Fatten (or Displace modifier) the rest of the tube, and then Bridge Edge loops between the caps and the rest of the tube to reconnect and fill the gap. – Robin Betts Sep 30 '21 at 16:53
  • Hello, thank you for the answer. I tried to delete the surfaces of the inlet and outlets, but they are not a single surface. They are composed of very small triangular elements and since the zoom sensitivity is not that great, it's very difficult to delete every single one. Do you know if there is a tool which selects the entire surface automatically? – Okra Oct 01 '21 at 11:05
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    Hide big irrelevant chunks, concentrate on one cap at a time, Shift-G Select Similar > 'Normal' might do it. If you can't zoom in, your clip-range might be wrong for the size of your model. You can share it if you like, at https://pasteall.org/blend/ – Robin Betts Oct 01 '21 at 11:15
  • Hello Robin, thank you for the reply. I have shared the geometry through the link you provided (hopefully correctly) under the name geometry_A. – Okra Oct 04 '21 at 07:12
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    @Okra.. you've got to copy and paste the link to make it available to us, here... – Robin Betts Oct 04 '21 at 08:48
  • Hello, the geometry is 37 Mb and it's over the limit of 24 Mb. I cannot share the geometry through the pasteall platform. I followed the steps you provided to eliminate the caps, yet there are still some remnant vertices and edges that I cannot easily delete. In addition, sometimes the vertices the tool selected were triangular elements in other parts of the geometry, and I would not be able to manually search the geometry and find all the created "holes". – Okra Oct 06 '21 at 08:13
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    @Okra While stepping through the process, H hide the bulk, so you're only working on the relevant region. Add your caps to a vertex-group as you go along, to stash the selection. Consider other traits to select by, for later steps - e.g. number of adjacent faces to edge, to find boundaries. – Robin Betts Oct 06 '21 at 09:29