Does anyone have experience with IGES geometry formats?

In some Matlab code I have, I generate airway trees for lung geometry. I want to be able to bring these into Autocad for some fine-tuning before I bring these into COMSOL, but I am having trouble transforming it into a IGES Geometry format.

I understand there is a igesout matlab function, but the geometry I have is not composed of curves; its composed of cylindrical segments that add up to a binary tree. I looked at it for a few days, but I'm not entirely sure if it's usable with my application.

Does anyone have any advice? I'm by no means a MATLAB expert, and I would appreciate any input you can offer.

Also, I made a quick visualization of the binary tree I am talking about (you can find the pictures here: http://imgur.com/wt6WV,awCbn#0)

For the geometry I export it to a quasi-.msh format. It consists of all the point coordinates, and the point connectivity in a geometry file (point connectivity meanine 1 connected to 2, etc) and a parameter file that contains the cylindrical radius for each segment.

[Sven]

I've had a little experience trying something similar that needed to adjust the matlab2iges tool to account for a new geometry type. I remember it was tricky, but there might be things we can try.

I assume you're using the MATLAB2IGES file exchange entry?

I would start by ignoring your full network of cylinders and just start with one test case. Can you put the code for how you store this cylinder definition in MATLAB?

[Brian]

I am not familiar with the matlab2iges tool, actually. I was looking at the igesout.m file, and the other one I found was iges2matlab. Can you show me where to get the matlab2iges tool?

And, how I store the cylinder information looks something like this:

I use:

* A point coordinate matrix (3 by N points),

* A Face matrix (2 by N segments), and

* A radius array (1 by N segments)

Basically how this works is I have the coordinate matrix as the x, y and z coordinates for each point. I then take my Face matrix, and mention in that category the connection of the points. It always starts with 1 2, meaning point 1 from the coordinate matrix is connected to 2, and it usually then diverges to 2 3 and 2 4, meaning point 2 connects to points 3 and 4. Once the file is read, I then take the radius array and tell Matlab to draw each cylinder as thick as the radius specified in the array.

So, a typical file usually looks like (ignore the header information):

(0 "Geometry Information File for Airway Generation")

(0 "Dimension:")

(2 2)

(10 (0 1 8 1 3))

(10 (0 1 8 1 3)(

0.000000E+000 0.000000E+000 0.000000E+000

0.000000E+000 0.000000E+000 3.000000E+000

0.000000E+000 1.422527E+000 4.865867E+000

0.000000E+000 -1.426915E+000 4.852017E+000

1.112550E+000 2.307275E+000 6.026353E+000

-1.115982E+000 2.300708E+000 6.017739E+000

1.108603E+000 -2.314392E+000 6.003890E+000

-1.112023E+000 -2.307805E+000 5.995340E+000

))

(0 "Faces:")

(13(0 1 7 0))

(13(3 1 7 3 0)(

2 1 2 0 0

2 2 3 0 0

2 2 4 0 0

2 3 5 0 0

2 3 6 0 0

2 4 7 0 0

2 4 8 0 0

))