Drawing contextual log-polar bins in MATLAB

Question

I use form context histograms as a function descriptor to encode silhouette images. To help with debugging, I would like to look at the log-polar shape containers superimposed on the silhouette image (reference points taken from the edge image).

An example of how it should look for one of the points is as follows:

I know how to display circles (radial bins), but it's hard for me to create angular bins (rows).

Given a set of angles, how to draw line segments similar to those shown in the example image?

Answer 1

Performing this action:

  >> figure
 >> axes
 >> hold on
 >> radius = 1;
 >> theta = 0: 30: 360;
 >> for angle = theta
 line ([0 radius * cosd (angle)], [0 radius * sind (angle)]);
 end

produces the following:

Answer 2

You can use this function:

function scDrawPolar(samp,point,r_min,r_max,nbins_theta,nbins_r) %SCDRAWPOLAR draw a polar on the center point % point - the center point % r_min - min radius % r_max - max radius % nbins_theta - theta divide % nbins_r - r divide % fig_handle - draw the diagram on which figure gca; hold on; plot(samp(1,:)',samp(2,:)','r.'); plot(point(1),point(2),'ko'); r_bin_edges=logspace(log10(r_min),log10(r_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(r_max*cs + point(1), r_max*sn + point(2),'LineStyle', ':', ... 'Color', 'k', 'LineWidth', 1); axis equal; axis off; hold off; end 

See the result here :