% Function to make ramps test surface for shape from shapelet testing % % Usage: % function [z,s,t] = testp(noise) % % Arguments: % noise - An optional parameter specifying the standard % deviation of Gaussian noise to add to the slant and tilt % values. % Returns; % z - A 2D array of surface height values which can be % viewed using surf(z) % s,t - Corresponding arrays of slant and tilt angles in % radians for each point on the surface. % Copyright (c) 2003-2005 Peter Kovesi % School of Computer Science & Software Engineering % The University of Western Australia % http://www.csse.uwa.edu.au/ % % Permission is hereby granted, free of charge, to any person obtaining a copy % of this software and associated documentation files (the "Software"), to deal % in the Software without restriction, subject to the following conditions: % % The above copyright notice and this permission notice shall be included in % all copies or substantial portions of the Software. % % The Software is provided "as is", without warranty of any kind. % July 2003 - Original version % August 2005 - Changes to accommodate Octave % September 2008 - Needle plot reinstated for Octave % January 2013 - Separate code path for Octave no longer needed (random() % is part of statistics package) function [z,s,t] = testp(noise) if nargin == 0 noise = 0; end p1 = [zeros(1,15) [0:.2:10] zeros(1,15)]; p2 = zeros(1,length(p1)); n = ceil(length(p1)/2); p3 = [1:n n:-1:1]/n*6; p3 = p3(1:length(p1)); z = [ones(15,1)*p2 ones(15,1)*p1 ones(15,1)*p3 ones(15,1)*p2]; figure(1); clf;% surfl(z), shading interp; colormap(copper); surf(z); % colormap(white); [dx, dy] = gradient(z); [s,t] = grad2slanttilt(dx,dy); [rows,cols] = size(s); if noise t = t + random('Normal',0,noise,rows,cols); % add noise to tilt s = s + random('Normal',0,noise,rows,cols); % ... and slant % constrain noisy slant values to 0-pi s = max(s, 0); s = min(s, pi/2-0.05); % -0.05 to avoid infinite gradient end figure(2),needleplotst(s,t,5,2), axis('off')