MATLAB: Determine size of object in image having two laser spots.

length of object having two spots at specific distance

hi all, i'm new to matlab and have started work on determining size of object in image, by this i mean length of object not in pixels. The idea is i've used two laser beams of fixed length and i take a picture of object having two laser spots on it. By this fixed laser spots i want to calculate length of that object. Can someone suggest me an algorithm to do this?

many thanks..

Best Answer

How about using imdistline() for a manual method? Or for an automatic method you'll have to locate those two spots, perhaps by thresholding or color segmentation, then use the Pythagorean theorem to get the Euclidean distance.

Check out my image segmentation tutorial: http://www.mathworks.com/matlabcentral/fileexchange/25157-image-segmentation-tutorial-blobsdemo

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MATLAB: How to convert Pixel to cm or inch (i want to know 1 pixel equal = ?? mm or = ?? cm = ?? inch)

Hello , But how can i find the real length of dicom image if that is taken from a online data source. i can not use ruler to measure its mm size? Is there any way.

MATLAB: How to calculate distance in centimeters using IMDISTLINE

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.

Best Answer

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MATLAB: How to convert Pixel to cm or inch (i want to know 1 pixel equal = ?? mm or = ?? cm = ?? inch)

MATLAB: How to calculate distance in centimeters using IMDISTLINE

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