generic fourier descriptor

hi i am implementing generic fourier descriptor in matlab.in one step i have to calculate the maximum radius of the shape.mostly my shapes will not be circular.the objects i have in my image are gun,knife,waterbottle,i dont have idea of calculating radius for these shapes in code.pleas help me on this...

Answer 1

[Walter Roberson]

For any one shape, it would be the maximum distance between the centroid of the shape and any point in the shape. So if you were to place a circle at the centroid of the shape, then what is the smallest circle radius that would include every point in the shape?

Answer 2

[Lucas Silva]

Use the following idea:

1 - Binarize the image so that you have only the object to be described

2 - Take the centroid of this figure and the extreme points, use the "regionprops" command to have information about these two characteristics

3 - Make the Euclidean distance from each extreme point to the centroid and take the biggest