Messages from Usenet group comp.lang.idl-pvwave, compiled by Paulo Penteado
find the maximum diameter of an object in an image
Hi folks, I have some CT data (of meteorites, not people) that I'm extracting slices of. The actual images I'm taking slices of are images where grains in the image have been set to 1, and everything else set to 0....so these are binary images. What I want to do is take a slice out of the CT volume, find the grains in the slice (which I'm doing with David Fanning's FIND_BOUNDARY() function), and then find the longest straight line that you can draw through the object (that goes from one boundary, through the center point, and then to the opposite boundary), which is its maximum diameter. FIND_BOUNDARY() gives me both the outline of the object and the center point, so I have that to work with. It also gives me perimeter and area, so I'm wondering if there isn't some kind of geometry trick that I haven't thought of that will get me what I need. If I do a principal components analysis on the boundary coordinates, wouldn't that be the maximum diameter? If anyone can point me in the right direction, or has some code they'd like to share, I'll be very grateful. Thanks, Jeff