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How to generate polar shape matrix of binary image?

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Rujal
Rujal on 21 Feb 2016
Edited: Rujal on 21 Feb 2016
Hello friends,
I want to know how to generate a polar shape matrix from an binary object. I have done my implement up to drawing polar diagram but I don't get idea how to generate shape matrix. My code is:
if true
% code
J=im2double(imread('images\sample1.jpg'));
K=rgb2gray(J);
I=im2bw(K);
radius_min=0;
radius_max=100;
angle=360;
make_square=0;
clc;
close all;
% Check the argument data
if (nargin < 1)
error('Error in the number of arguments (it should be >0). Use: I,radius_min,radius_max,angle,make_square');
end
% Check if there are some arguments by default
if exist('radius_min','var') == 0
radius_min = 0;
end
if exist('radius_max','var') == 0
radius_max = 100;
end
if exist('angle','var') == 0
angle = 60;
end
if exist('make_square','var') == 0
make_square=0;
end
% Check if the input argument data are valid
if (radius_min < 0)
error('radius_min sholud be >=0')
end
if (radius_max <= radius_min)
error('radius_max sholud be >radius_min')
end
if (angle<0 && angle>360)
error('angle sholud be 0<=angle<=360')
end
if (make_square ~= 0 && make_square ~= 1)
error('make_square sholud be either 0, or, 1')
end
% Plot the input image (rectangular coordinates)
figure(1)
%I=imadjust(I); %activate if needed
imshow((I));
title('Input image (rectangular coordinates)')
[M N]=size(I);
% If the option make_square==1, the input image is resized
if make_square==1
if(M>N) dim=M;
else dim=N;
end
I=imresize(I,[dim dim]);
[M N]=size(I);
end
% We rotate pi/2 the input image to have the desired view
I=imrotate(I,90);
% The mapping from cartesian to polar coordinates
theta_max=angle;
step_theta=theta_max/(N-1);
step_r=(radius_max-radius_min)/(M-1);
[r,theta] = meshgrid(radius_min:step_r:radius_max, -theta_max/2:step_theta:theta_max/2);
xx=-r.*cos(theta*pi/180)-radius_min;
yy=-r.*sin(theta*pi/180)-radius_min;
% Map the input image I to the polar coordinates xx,yy and represent as
% a surface surface (viewed from above)
figure(2);
H=surface(yy,xx,im2double(I),'edgecolor','interp');
colormap(gray)
view(0,90)
axis off
title('Output image mapped to polar coordinates')
% figure
% polar(theta,r);
point =[97.31;92.12]; %- the center point
nbins_theta =8; % - theta divide
nbins_r =5; %- r divide
h2 = axes('position',[0 0 1 1]);
gca;
hold on;
r_bin_edges=linspace(radius_min,radius_max,nbins_r);
% draw circles
th = 0 : pi / 50 : 2 * pi;
xunit = cos(th);
yunit = sin(th);
for i=1:length(r_bin_edges)
line(xunit * r_bin_edges(i) + point(1), yunit * r_bin_edges(i) + point(2),...
'LineStyle', ':', 'Color', 'k', 'LineWidth', 1);
end
% draw spokes
th = (1:nbins_theta) * 2*pi / nbins_theta;
cs = [cos(th);zeros(1,size(th,2))];
sn = [sin(th);zeros(1,size(th,2))];
line(radius_max*cs + point(1), radius_max*sn + point(2),'LineStyle', ':', ...
'Color', 'k', 'LineWidth', 1);
axis equal;
axis off;
hold off;
end
And the result is :
The further process is to generate polar shape matrix. The concept is If the circles intersect the maximum radius of the shape (line OA) at i1,i2,..., in-1, then starting from i1, i2, ..., in-1 and counter-clockwise, we divide each circle into m equal arcs, each arc being theta = 360/m degrees. Then an m x n matrix - which called shape matrix.
I would be thankful if someone helps me to implement this. Thanks in advance.

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