View Full Version : Tube inserted / advanced through vessels help!

05-21-2009, 01:21 PM
I need to make a long catheter (long flexible tube that fit's inside arteries and veins) follow along inside a vessel system. It starts at the jugular vein and goes down into and through the chambers / valves of the heart...

I've tried a simple tube clloision obeject, which seems like the best solution in terms of controling of the path of the advancing catheter and adding a 'cloth' dynamic to the catheter... this works pretty well but the geometry of the catheter immediately gets 'flat' is the collision contact begins...tried all possible settings to try and keep the object's round shape? This is like "almost there" but maybe I'm just a few tricks short of making it work???

I've tried with bones and IK and it just cant stay with all the turning (it needs to always stay inside the vessels and when it turns and goes back up through the heart... not so good...

Tried serpent displacement plug in, could not bring that together either

any help in resolving this delema... I would be forever greatfull

[email protected]

05-21-2009, 01:32 PM
Dynamics would be a nightmare. Perhaps if you got a chain of 2-point polys to be the catheter, and FX_Link the catheter, you wouldn't have flattening going on...

I've done similar things many, many times. For this job, I'd take the vessel along which I'd have to advance the catheter, kill the polys, weld average points along the way until I had a spline path that stuck to the center of the lumen the whole way.

This spline path could be used to create a chain of skelegons over which the catheter could be advanced. I don't know if Serpent could use a path, but if it could, your path is easy to make. With bones, you can of course animate those bones as the catheter advances, giving some life to the animation.

05-21-2009, 01:44 PM
ok...2 point poly chain and FX_link the cath... I will try that

the bone thing....I understand how I could model / position a chain of bones, but then advance the cath object over them? the bones would belong to the catheter object right? then how would you move the object over the bones when they would just move w/ the object they belong to?

05-21-2009, 02:00 PM
Ah... the old morph-over-bones trick... Endlessly useful for medical animations.

Picture this. Model your catheter right from Z=0 back into the negative Z direction. Now draw a spline out so that it runs straight from the back of the catheter to the tip, then on into the positive Z direction. But you can add curves in that path, once you're into the positive Z numbers. Convert that path into skelegons.

Make a morph target for the catheter called Advanced. For that morph, just move the catheter in the positive Z axis, far enough so that it would follow that path of skelegons.

Now, in Layout, convert the skelegons to bones, then set the rest rotations on all those bones to zero in heading and pitch. (Best done in the Scene Editor, so you can do them all at once.)

For bone properties, make sure you've checked off "use morphed position." Now, when you animate that morph... yes, the catheter follows the path of those bones.

You'll find you need pretty short bones to keep the path that the catheter follows pretty. You'll probably want one of the cooler curve creation tools in Modeler to create your path. Well, in the case of this project, if you use the existing points in your anatomy model, you'll probably have a pretty tight spacing, which is good. It just means you'll have more bones. Just remember to set the Rest Rotations to zero for all those bones.

05-21-2009, 02:09 PM
can I discuss this w/you on a phone line?? think I get it, but easier than the typing for me... been in LW for years, would only take a few minutes for me to grasp, thanks!

05-21-2009, 02:20 PM
Still at work, boss sitting a few feet away. Give it a whack with a really simple test. Make a tube with a morph target. Draw your bones in Layout so you don't have to fool with resetting rest rotations. If you still have trouble, try me again in 2 hours and I'll be able to talk.

05-21-2009, 02:23 PM
Thanks so much... the "bells just went off" I get it... works great...f'n aye

05-21-2009, 04:30 PM
I would use DStorms trailer plugin. Its much more powerful then LWs serpent plugin.

05-21-2009, 11:04 PM
Hi again,

I tried a quick test and seemed to work out, so tonight I spent time on doing the full gig on my scene / objects ect. and weirdness is happening...the catheter is not following the bone path at all

I have the model moved to the location of the jugular vein (no longer centered) and the main movement is on the Y axis... can you check out this scene


and see what might be the issue? I modeled the spline for the skelegon path...made the bones... zero'd out the heading / pitch rest values...checked 'used morphed positions"..

it's a simple scene, the few objects are included, is it to do with the object not being centered in modeler? any help would be so appreciated


05-21-2009, 11:06 PM
by the way, if you do check the scene out... there are no maps included for purposes of size etc. thanks


05-22-2009, 03:30 AM
perhaps try the streamers technique
greg sullivans streamer tutorial

05-22-2009, 06:32 AM
Okay, I looked at the scene. Is the bone chain at least set up to follow the correct path? It doesn't seem to be inside any anatomy.

As for the catheter not following the bones, that's because when you set up skelegons, whatever crazy path you make in Modeler, all the bones are considered 'at rest' in those positions. You have to tell Layout that their positions are to be considered 'modified.'

In other words, just go through each bone (except the first) and set it's Rest Position to zero on heading and pitch. It's slow to do them one at a time, so I recommend learning to do it in the Scene Editor. Here's the steps for doing that. (It seems like a lot, but it's easier than doing all the bones one at a time.)

Open Scene Editor. Choose the object with the bones. Right click it and select Open Child Items (Recursive). Select the second bone. (Not the first, as it has some initial rotation that it needs to keep.) Shift select the last bone, so all but the first bone are highlighted.

Now, over on the right side of the window, select the "Property" tab. Look for the column called Rest Heading. On the column heading button, right click and choose "Apply Item Selection to This Column's Cells." Do the same for Rest Pitch.

Now, in one of the highlighted cells, notice the tiny column at the leftmost part of the column. Right click on any one of those numbers. On that menu, select the first item to open the Adjust Properties panel. On this panel, make sure "Change Value to:" is set to zero. Then click the Apply button. You're done. Close the scene editor and your morph will follow the bones.

05-22-2009, 11:09 AM
thanks for looking at the scene...

yes, I modeled the spline exactly (see the model layers in modeler) where it should go? and I set all the rest positions to 0. at frame 0. for heading and pitch (which makes the chain look like a stright line)... before doing that, the chain was in the correct spot... so then after the bone reset thing and morfing the catheter move (which was down in tnhe Y in this case) it does not follow the path??


05-22-2009, 11:14 AM
look at the model in modeler...check out layer 2 or 3 with layer 4 in the BG (which is the inner anatony the bones make the path through??

it's all there, just not jiving in Layout?

05-22-2009, 11:21 AM
I got this to work. I had to kill all your bones. They were, for some reason, set in a very straight line. I converted your skelegons, reset all the rest headings and pitches, and it works like a charm.

Oh, did you set the bones' rest positions in the bone properties tab, or with the HPB boxes in the lower left of Layout? That's two different things.

05-22-2009, 11:25 AM
I was not up for the scene editor (old school classic is what I know), so I did all that work in the lower left boxes...not the same?... 561.274.0766 or can I call you?

05-22-2009, 11:27 AM
I was not up for the scene editor (old school 'classic' is what I know), so I did all that work in the lower left boxes...not the same?... 561.274.0766 or can I call you?

05-22-2009, 11:46 AM
thank you so much again 'nadgleator'... all is doing what it's supposed to and I can say "whew" and on we go....