how can i get a length of a barrel in an image using matlab

Answer 1

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/244691-showing-specific-frame-in-a-video-file#comment_311785

Answer 2

[Image Analyst]

See my attached spatial calibration demo. Of course you first need to put something of known length into the image, such as a yard stick or tape measure, so you can figure out how many pixels equal one centimeter.

[sree hari]

i compressed the image and find out the area of the drum but i cannot able to find out the length of drum as per my requirment

[Image Analyst]

Then see this

[sree hari]

i checked the code, in that the process of measuring length is done manually. i want to find the length directly by coding.

[Image Analyst]

You can get it in pixels but until you put an object of known length in there, such as a meter stick, you can't get the length in meters.

[Walter Roberson]

I did a search for those wavy "pavers" (paving stones). I could find stock images of them, but I could not find anyone who sells them in the time I looked -- all of the places that I checked that seemed to have them had something quite different. If we knew what the physical size of the stones was then we could use that to calibrate the perspective and so to calculate the size of the barrel.