IDL and Snakes!

[Ronn Kling <klingrl(at)juno.com>]

Everyone,

A few weeks ago Erich Sorantin posted a question asking if anyone had
written a program in IDL using snakes.  Well, I have one now.  

Snakes (also called active contours) are a way of determining edges of
features in images that conventional techniques fail on.  For instance,
suppose one wanted to contour the intersection of a bump on a steep
hill.  A single level will not work since the downhill side of the bump
is at a lower level then the uphill side.  Snakes will give you this
intersection since they find the edge using a combination of point
spacing, curvature and gradient information.

If you would like to see this program work I have placed two save files,
a sample tiff image, and a help file on ftp.cis.upenn.edu in the
incoming directory. Just log in using anonymous and download either
snake_50.sav (if you are using IDL 5.0) or snake_51.sav (for 5.1). Make
sure you are in binary mode for these and the square.tif file.  Finally,
download the snakehelp.txt for details on running the program.  Restore
the save files and then type snakedemo at the prompt and the program
will begin.

If anyone is interested in getting the source code for these please
email me at the address below and I will get it to you.

Ronn Kling
Ronn Kling Consulting
klingrl@juno.com