points on a contour and meshgrid

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ttopal
ttopal 2017-3-7
回答： KSSV 2017-3-8
Hi,
I have a set of points on a contour, and a meshgrid of points. I need to use all the points in this meshgrid except when it falls on the contour. Is there a way other than comparing each point?
here is the code and the result graph;
I = imread('circle.png');
format long;
% figure(1)
% imshow(I)
IM = im2bw(I);
IM2 = imcomplement(IM);
[r, c] = find(IM2, 1, 'first');
mycontour = bwtraceboundary(IM2, [r c] ,'E',8,Inf,'clockwise') ; % returns x,y points
[a,~]=size(mycontour);
mycontour2 = [mycontour(1:30:a,1),mycontour(1:30:a,2)];
%this line is to adjust the points to reasonable scale in excel.
mycontour3 = [(mycontour2(:,2)-800)/1000,(mycontour2(:,1)-640)/1000];
xlswrite('known_point_set.xlsx',mycontour3);
% figure(3)
% imshow(I)
hold on;
plot(mycontour3(:,2),mycontour3(:,1),'*r','LineWidth',1); %(plot y vs x)
[X,Y] = meshgrid(-1:.1:1);
hold on;
plot(X,Y,'.k');

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采纳的回答

KSSV
KSSV 2017-3-8
How about doing interpolation with the contour points and mesh grid points with no extrapolation. If the meshgrid point lies on the contour, it will result into some value, if not a NaN; this helps in finding out whether point lies on contour or not.

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