Hi guys, joined in today and this is my first question here. I need help with Fourier Descriptors.

Suppose x1 is a set of points describing a line ( not a straight line but a line drawn by hand ), and let F1 be its fourier descriptor. Similarly, x2 is a set of points describing another line which begins at one of the end points of the line x1, and let F2 be its fourier descriptor.

Let F be the fourier descriptor of the entire figure involving the 2 lines, x1 and x2. so, F is calculated considering all the points in both x1 and x2 lines, in the drawing order.

I want to know if we can define a descriptor for the figure without calculating the Fourier Transform for the entire figure. Instead, use the fourier descriptor for the lines and the relative angular difference to create a descriptor. like,

F' = F1 + (angle) F2 to describe the figure.
I know that in this case F [NOT]= F', but is it possible?