Asking for some suggestion

[jenny_wui]

Hello, I am going to work with human intestine model. A pill cam will pass through the intestine and look for any abnormalities inside the intestine. First I need to figure out some suitable modelling technic depending on the data. But the problem is the pill cam. It will move through the intestine and I need to model every cross section while the pill cam taverses through the intestine. Could anyone give me some suggestion ? I think at first I need to find out the medial axis of the intestine and then pass the pill cam along the medial axis. I need some suggestion as how to find out the medial axis for a complicated data like intestine. Could you provide any suggestion or help? Thanks in advance.

[tonyo_au]

I would look at this as a camera following a path and always looking forward - think of a first person shooter following a path or a drive down a road - the intestine path could be constructed from a set of quadratic curve equations like bezier

[jenny_wui]

Hi, thank you very much for the suggestion. I am a bit confused about finding out the medial axis of human intestine. As though tubular in shape, original data may not be able to detect it. Could any one give me some suggestion regarding this?
Thanks in advance.

[jonpb1]

I don't know if this is any help, but I actually can't think of a way to find the medial axis without first finding the cross-section. I believe the cross-section of minimum area will give a plane who's normal will be the medial axis direction and the centriod of that cross-section will give you position in space of the axis. Assuming you start with a optimal cross-section, moving a small distance will require only a small angular span to test the cross-sections of the next location. But this method sounds very computationally intensive.

[tonyo_au]

This might help - but it assumes you have the intestine cross-sections.
http://w3.impa.br/~paesleme/MedialAxis/MedialAxis.html
http://spacesymmetrystructure.wordpr...noi-skeletons/

Are you planning to create a medial axis of the longitudinal cross-section?

[jenny_wui]

Yes, I think I need to pass the camera through the X-section of the intestine.

[tonyo_au]

If you are only worry about the cross-section the medial axis isn't of much use I think what you want is the centroid of the polygon defining the cross-section. Moving from centroid to centroid of cross-sections will keep your camera roughly centered as you move down the intestine. You will need cross-sections at frequent points along the intestine (especially on the bends) for this to work.

What input data do you have?

[jenny_wui]

I am waiting for data from doctors. I am still a bit worried about the X-section as a particular X-section may consist of several tubes, but at a time I am concerned with a particular tube, how to separate one tube from another. I am looking for some suitable method for finding out the x-sections at different positions.

[jenny_wui]

Picture1.gif

I have attached the obj file. Now I need to trace path along the tubular model. How could that be done?

[tonyo_au]

So you just have the obj mesh of the intestines. That make life more complex. Perhaps you could move a virtual object through the intestine with collision detections and record the successful path. Now you have a path that the camera can follow.