xralflin.m

等高线拟合源代码（matlab源码）

function xralflin(delta_step, nr_of_points, at_line)

% Part of GUI
% Calculate distance xr and angle alfa by linear regression
% Draw found tangent to contour
%
% 21 april 1999
% Walter Verdonck,

% All the software included in this package is presented as is.
% It may be distributed freely. The author can, however, not be
% held responsible for any problems whatever.
% 
% Designed by Johan Baeten, Walter Verdonck
% Last updated: 29-03-2000
% [e-mail]

global BEELD MAINFIG

BEELD = get(MAINFIG, 'userdata');
[im_xs, im_ys] =size(BEELD);

if nargin  == 3 ,
   delta = delta_step; 
	m = nr_of_points;  
	al = at_line;
else
	delta = 2; % distance between consecutive lines to search points
	m = 5;     % number of points for least squares Solution
	al = im_ys/2; % at the center line 
end


startpos = [1 al-delta*floor(m/2)];

for j = 1:m
   [x(j) y(j) color] = iseffil(startpos,0,im_xs,0);
   startpos(2) = startpos(2) + delta;
end

y=y-al;
y(2,:)=1;
p=y'\x';

line(polyval(p, [y(1)-6 y(length(x))+6]),[y(1)+al-6 y(length(x))+al+6]);

results = [' ... Results: Distance (from left) ' num2str(p(2)-0.5) ];
results = [results ' [pix] and angle (with vertical axis) ' num2str(p(1)) ' [rad].'];
seterror(results)