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Determine object size in 2D image ?

asked 2019-07-25 05:35:10 -0500

Determine object size in 2D image ? Given an photograph of a person I want to determine how tall the person is. I have the following information: - picture 12M pixel - the camera's parameters from the images EXIF (focal length: native and 35mm equivalent, resolution, aperture and shutter-speed) - the dimensions of an object held by the person (at the center of the torso). But I have only four points of one small object 10x6 cm. Is this enough - or do I have to live with the inaccuracy ?

Which is the best and most accurate method to determine how tall the person is ?

Thanks

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answered 2019-07-25 09:20:22 -0500

Witek gravatar image

The quickest estimate (of a persons height) would be to find the pixel size of the object held by the person and calculate the scale factor sf=real object size/object size in pixels. Since the known object is practically at the same distance as a human, you can just multiply the height of the person in pixels by the factor and there you go. If you need it to be automatic, you need an easily distinguishable object (black square/circle on a white background?) and a human detector. There are many of them (hog detectors, Haar classifiers, deep networks) and you need to see which one is the most precise in estimating the human silhouette. I believe Haar detector is the easiest in implementation. Just replace the face cascade with fullbody cascade.

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Asked: 2019-07-25 05:35:10 -0500

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Last updated: Jul 25