Circular mask and its division

Hi all,

I need to draw a circle as the initial level set . Then I am required to draw the semi-diameters of the circle for every center angle (pi/360) and randomly selecting 20 points on every diameter.

A circular mask is easily drawn. I have used this code:

[y x] = meshgrid(1:100,1:100);

m = ((radius).^2)-((x-xcen).^2)-((y-ycen).^2)>radius;

%To make it a signed distance function I have further used the command

initial_level_set = bwdist(m)-bwdist(1-m)+im2double(m)-.5;

I cannot able to draw the semi - circles and extract those points.

Any help will be greatly appreciated.

Thanks all!