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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.

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  • $\begingroup$ Do you want the size of the inlets and outlets to be fixed, or just their location? $\endgroup$
    – Robin Betts ♦
    Sep 30, 2021 at 10:41
  • $\begingroup$ 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. $\endgroup$
    – Okra
    Sep 30, 2021 at 11:01
  • $\begingroup$ One approach is to use bones to animate the inflation of the arteries. See this answer - blender.stackexchange.com/questions/70151/… which illustrates how to do this to animate a beating heart. $\endgroup$
    – Ed Tate
    Oct 4, 2021 at 2:39

1 Answer 1

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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.

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    $\begingroup$ @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. $\endgroup$
    – Robin Betts ♦
    Sep 30, 2021 at 12:43
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    $\begingroup$ Ahh.. good. Do you want solid-walled tubes, or the ends of the vessels to be capped (blocked)? $\endgroup$
    – Robin Betts ♦
    Sep 30, 2021 at 13:25
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    $\begingroup$ 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). $\endgroup$
    – Okra
    Sep 30, 2021 at 13:42
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    $\begingroup$ @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. $\endgroup$
    – Robin Betts ♦
    Sep 30, 2021 at 16:53
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    $\begingroup$ 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 pasteall.org/blend $\endgroup$
    – Robin Betts ♦
    Oct 1, 2021 at 11:15

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