Extracting range of an object from an image using object's dimesntions
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So I have a code that detects and isolates three objects and yields their dimensions in pixels (diamters, perimeter..), I have the ground truth data for the distance but I would like to be able to estiamte the distance from the inforamation I have efficiently, suggestions to how this could be done would be great.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/166764/image.png)
The picture shows a frame from over a thousand frames I have that show the object slowly drifting closer, so obviously the closer it is the larger its measurements are.
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Image Analyst
on 18 Aug 2017
Measure the diameters and separation for images taken at multiple distances. Then divide the actual diameters and separation by the pixel ones to get a spatial calibration. Then plot spatial calibration vs. distance to get a curve. Fit to a polynomial with polyfit to get a formula where you can convert the real world diameters into a distance from the camera.
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Matt J
on 18 Aug 2017
For a simple pinhole camera model (and ignoring off-axis effects), the relationship between distance and perimeter (in pixels) should be
distance=K/perimeter
Just fit the constant K with as many (perimeter,distance) measurements that you have.
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