MATLAB: How to calculate distance in centimeters using IMDISTLINE

distanceImage Processing Toolbox

i want to find out height of a sleeping infant. for that i want to find out the distance in cm. using 'imdistline' i'm getting the distance in pixels but how to convert that in cm?

Best Answer

Put a ruler, a tape measure, a standard sheet of paper, or anything else of known length into the scene. Then snap a picture of it and use imdistline() to find the length in pixels. For example, let's say you laid down a sheet of A4 paper and measured it's distance as 2100 pixels. Knowing that it is 21 cm long, you get a spatial calibration factor of 21/2100, which you multiply your distances in pixels by to get the distance in cm. Multiply by that calibration factor squared to convert the area in pixels to the area in square centimeters.
calibrationFactor = 21/2100;
distanceInCm = distanceInPixels * calibrationFactor;
areaInSquareCm = areaInPixels * calibrationFactor ^ 2;
It's in the FAQ.
See my demo attached below for a really nice demo.
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