| Feature identification and measurement [message #73353] |
Mon, 01 November 2010 12:21  |
wlandsman
Messages: 743
Registered: June 2000
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Senior Member |
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I am working on testing an optical system in which several features
(circles, crosses, lines, a "ladder") are imaged onto a CCD. We
use these fiducials to monitor changes in the optical path (each
fiducial can shift independently), and so are interested in measuring
their relative positions.
My first thought was that this might be a case to take advantage of
all those IDL remote sensing tools that astronomers mostly ignore.
I started to read about shapefiles, but there seemed to be a lot of
overhead just to get started.
Right now I am using the Canny function to detect edges, and then
LABEL_REGION to isolate the different features, and fitting each
fiducial separately (eg. the lines with LINFIT(), the circles with
mpfitellipse ) to get their position. But Canny + Label_region
doesn't work perfectly -- either the fiducial is not entirely within
one LABEL_REGION value, or it includes pixels that I don't want to
measure. So I spend a lot of time interactively changing pixel
values or selecting points to fit. I'd welcome any advice on tools
that might help with these measurements. Thanks, --Wayne
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