GLTree Matlab Example: Radius Search Function
February 15, 2010 by Luigi Giaccari
Filed under: Computational Geometry, Optimization
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Filed under: Computational Geometry, Optimization
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RSearch2D query a GL-Tree for Radius search
SYNTAX
idc=RSearch3D(p,qp,ptrtree,r);
INPUT PARAMETERS
- p: [2xN] double array coordinates of reference points
- qp: [2x1] double array coordinates of query points. NOTE: differently from NNsearch this function does not support multiple query points.
- ptrtree: a pointer to the previously constructed GLtree.Warning if the pointer is uncorrect it will cause a crash, there is no way to check this in the mex routine, you have to check it in your script.
- r: double value, radius to perform the search.
OUTPUT PARAMETERS
- idc: [?x1] column vector, each rows contains an index of a point found in the range described by the radius.
GENERAL INFORMATIONS
-Conditions for a point to be found in the radius is <=, so
points with distance from the query=r will be returned.
For question, suggestion, bug reports
giaccariluigi@msn.com
Author: Luigi Giaccari
EXAMPLE
function test() N=200;%reference points k=3;%k neigh p=rand(N,2);%reference points qp=rand(1,2);%query point r=.1;%radius for search fprintf('RANDOM POINTS GENERATED\n\n') fprintf('BUILDING THE DATA STRUCTURE:\n') tic ptrtree=BuildGLTree2D(p'); fprintf('\tGLTree built in %4.4f s\n\treturned pointer %4.0f:\n\n',toc,ptrtree); fprintf('START RADIUS SEARCH:\n') tic [idc]=RSearch2D(p',qp',ptrtree,r); fprintf('\t %4.0f Points found in range\n\n',length(idc)); fprintf('DELETING THE TREE\n\n') DeleteGLTree2D(ptrtree); fprintf('TEST SUCCESFULLY COMPLETED !!!\n\n') %plot the NNG figure(1) title([num2str(k),' Neighbours'],'fontsize',14); axis equal hold on h1=plot(p(:,1),p(:,2),'g.'); h2=plot(qp(:,1),qp(:,2),'b+'); h2=circle(qp,r,30,'-b'); h3=plot(p(idc,1),p(idc,2),'r.'); legend([h1,h2,h3],'Reference points','Circle','Inside points'); end function H=circle(center,radius,NOP,style) %--------------------------------------------------------------------------------------------- % H=CIRCLE(CENTER,RADIUS,NOP,STYLE) % This routine draws a circle with center defined as % a vector CENTER, radius as a scaler RADIS. NOP is % the number of points on the circle. As to STYLE, % use it the same way as you use the rountine PLOT. % Since the handle of the object is returned, you % use routine SET to get the best result. % % Usage Examples, % % circle([1,3],3,1000,':'); % circle([2,4],2,1000,'--'); % % Zhenhai Wang <zhenhai@ieee.org> % Version 1.00 % December, 2002 %--------------------------------------------------------------------------------------------- if (nargin <3), error('Please see help for INPUT DATA.'); elseif (nargin==3) style='b-'; end; THETA=linspace(0,2*pi,NOP); RHO=ones(1,NOP)*radius; [X,Y] = pol2cart(THETA,RHO); X=X+center(1); Y=Y+center(2); H=plot(X,Y,style); axis square; end
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