http://www.k-wave.org/forum/topic/a-makeline-function-similar-to-makecircle Support for the k-Wave MATLAB toolbox en-US Tue, 12 May 2026 22:00:26 +0000 http://bbpress.org/?v=1.0.2 q http://www.k-wave.org/forum/search.php http://www.k-wave.org/forum/topic/a-makeline-function-similar-to-makecircle#post-79 Mon, 25 Oct 2010 14:39:52 +0000 Bradley Treeby 79@http://www.k-wave.org/forum/ <p>Hi Martin,</p> <p>Thanks for your contribution. I have moved your code to a new forum section for user submitted functions so we can keep them together in one place.</p> <p>Brad. </p> http://www.k-wave.org/forum/topic/a-makeline-function-similar-to-makecircle#post-76 Thu, 21 Oct 2010 09:48:30 +0000 Martin 76@http://www.k-wave.org/forum/ <p>Hello,</p> <p>I've created a function for making a binary map of a line, similar to the makeCircle function which makes a binary map of a circle or an arc. I made this mainly because I wanted to model planar transducers, but it can probably be useful in other ways as well. Here's the function:</p> <pre><code>function line = makeLine(x,z,r0,v,lineLength,lineThick) % MAKELINE - Create a binary map of a line on a 2D grid. % % DESCRIPTION: % makeLine creates a binary map of a line within a two-dimensional % grid (the line position is denoted by 1&#39;s in the matrix with 0&#39;s % elsewhere). % % USAGE: % line = makeLine(xx,zz,x0,z0,xu,zu,length,thick) % % INPUTS: % x, z - vectors of x and z positions of the grid % r0 - vector r0 = [x0 z0] indicating line center point % v - vector v = [vx vz] perpendicular to the line % length - length of line % thick - thickness of line % % OUTPUTS: % line - 2D binary map of a line % % ABOUT: % author - Martin H. Skjelvareid % date - 12th Oct 2010 % last update - % % See also makeCircle % COMMENT: % The function works by calculating the vector between the reference % point r0 and all other points. This vector is then projected along % the unity vectors parallel to and perpendicular to the line. If the % distance parallel to / perpendicular to the line is within the % constraints on the line length and thickness, the corresponding % grid point is added to the binary map of the line. %% Get size of input Nx = length(x); % Number of x points Nz = length(z); % Number of z points %% Create direction vectors of unity length v = v/norm(v); % Unity vector along line vt = [-v(2) v(1)]; % Unity vector perpendicular to line %% Create matrix representations of vectors [Z,X] = ndgrid(z,x); % Expand z and x to matrices R = cat(3,X,Z); % Concatenate X and Z along 3. dim R0 = repmat(reshape(r0,1,1,2),Nz,Nx); % Reshape r0 to 3. dim, duplicate V = repmat(reshape(v,1,1,2),Nz,Nx); % Reshape v to 3. dim, duplicate Vt = repmat(reshape(vt,1,1,2),Nz,Nx); % % Reshape vt to 3. dim, duplicate %% Calculate projections along/perdendicular to line dR = R - R0; % Calc. diff. vector between all points and r0 distAlong = abs(sum(dR.*Vt,3)); % Project diff. vec. along line distPerpend = abs(sum(dR.*V,3)); % Project diff. vec. prepend. to line %% Create binary mask of points within length/thickness constraints line = double((distAlong &lt;= lineLength/2) &amp; (distPerpend &lt;= lineThick/2));</code></pre> <p>and here's a simple test script:</p> <pre><code>close all clearvars dx = 0.1; x = -5:dx:5; z = -5:dx:5; r0 = [-1 -2]; % Line center point v = [2 3]; % Vector perpendicular to line width = 3; % Line width thick = dx; % Line thickness line = makeLine(x,z,r0,v,width,thick); figure imagesc(x,z,line) axis image colormap(1-gray(256)) hold on quiver(r0(1),r0(2),v(1),v(2),0) legend(&#39;Vector perpend. to line&#39;)</code></pre> <p>If you find this little code snippet useful, feel free to include it in future versions. :-) </p>