Active Contour Toolbox
05 Jul 2006
05 Jul 2006)
This toolbox provides some functions to segment an image or a video using active contours
|po_rouctangle(center, lengths, tilt, number_of_edges, resolution)
function rouctangle = po_rouctangle(center, lengths, tilt, number_of_edges, resolution)
%po_rouctangle: instantiation of a closed polygon sampling a chamfered rectangle
% p = po_rouctangle(c, l, t, n, s) computes a closed polygon sampling the
% chamfered rectangle of center c, lengths l, and tilt angle t with either n
% regularly spaced vertices (or equivalently n edges) or a vertex every s
% pixels. Resolution s is used unless n is strictly greater than 7. s does not
% have to be an integer. If n is strictly greater than 7, then it must be
% equal to 2*(i+j)+4 for some integers i and j. The chamfer at each corner is
% made by a single edge with an angle of 45 degrees with respect to the
% rectangle sides.
% l can be a 1x2 or a 2x1 matrix. t is in degrees.
%See also polygon.
%Polygon Toolbox by Eric Debreuve
%Last update: June 13, 2006
if number_of_edges > 7
resolution = 2 * sum(lengths) / (number_of_edges + 8 / sqrt(2) - 4);
half_lengths = lengths / 2;
corner = resolution / sqrt(2);
lengths = round((lengths - 2 * corner) / resolution);
if any(lengths <= 0)
rouctangle = ;
horizontal_side = corner + resolution * (lengths(2):-1:0) - half_lengths(2);
vertical_side = corner + resolution * (lengths(1):-1:0) - half_lengths(1);
height = corner + vertical_side(1);
rouctangle = [vertical_side, zeros(1,lengths(2) + 1) - half_lengths(1), ...
fliplr(vertical_side), height * ones(1,lengths(2) + 1); ...
(horizontal_side(1) + corner) * ones(1, lengths(1) + 1), horizontal_side, ...
zeros(1, lengths(1) + 1) - half_lengths(2), fliplr(horizontal_side); ...
ones(1, 2 * (sum(lengths) + 2))];
tilt = tilt * pi / 180;
cos_of_tilt = cos(tilt);
sin_of_tilt = sin(tilt);
in_place = [cos_of_tilt, - sin_of_tilt, center(1); ...
sin_of_tilt, cos_of_tilt, center(2)];
rouctangle = in_place * rouctangle;
rouctangle = [rouctangle rouctangle(:,1)];