How to get surface topology from fringe pattern

Question

I'm trying to recover the surface shape of a body from fringe pattern. There's a interferometer projecting circular fringes on the body. A camera takes a picture of the reflection of these fringes. I studied some papers doing this with unwrapping the phase of the fringen pattern. Unfortunately they don't go very deep, so I didn't get the link between the unwrapped phase and the resulting topology.

First I created a test pattern function:

def create_pattern_rings(dim, count_rings):

pattern = np.zeros((dim[0], dim[1]))
pix_per_ring = int((dim[1] / 2) / count_rings)
for ring in range(0, count_rings):
    radii_out = (dim[1] / 2) - ring*pix_per_ring*2
    radii_in = radii_out - pix_per_ring
    for y in range(0, dim[0]):
        for x in range(0, dim[1]):
            if (np.sqrt((x-dim[1]/2)**2 + (y-dim[1]/2)**2)) < radii_out and (np.sqrt((x-dim[1]/2)**2 + (y-dim[1]/2)**2)) > radii_in:
                pattern[y][x] = 1

With this pattern I do 2D fft to get the phase with numpy.angle(). This phase can be unwrapped using numpy.unwrap():

def calc_fft(data, shift):
data_fft = np.fft.fft2(data)

if shift:
    data_fft = np.fft.fftshift(data_fft)

return data_fft

def phase_unwrap(data_fft):
data_unwraped = np.unwrap(np.angle(data_fft))

return data_unwraped

But I don't know how to go one after this step. Any suggestions?

Thanks!