Finding LAT LONG inside a circle of a given LAT LONG .

Question

M M Nabi 2021-2-20

0
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https://ww2.mathworks.cn/matlabcentral/answers/751014-finding-lat-long-inside-a-circle-of-a-given-lat-long

回答： M M Nabi 2021-2-24

I have a LAT LONG (point A). I have another set of LAT LONG. I want to find LAT LONG points within 5km radius of point A.

How can I do that?

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Answer 1

Bruno Luong 2021-2-20

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https://ww2.mathworks.cn/matlabcentral/answers/751014-finding-lat-long-inside-a-circle-of-a-given-lat-long#answer_628534

编辑：Bruno Luong 2021-2-20

在 MATLAB Online 中打开

% Random data
lonA=rand*360;
latA=rand*180-90;
n = 10000;
lonP=rand(1,n)*360;
latP=rand(1,n)*180-90;
earthradius = 6357;
rA = 1000; % distance from A
[xA,yA,zA] = sph2cart(deg2rad(lonA),deg2rad(latA),1);
[x,y,z] = sph2cart(deg2rad(lonP(:)),deg2rad(latP(:)),1);
P = [x,y,z];
A = [xA,yA,zA];
% W. Kahan method
alpha = 2*atan(vecnorm(A-P,2,2) ./ vecnorm(A+P,2,2));
inrA = abs(alpha) <= rA/earthradius; % logical array, 1 if the distance from A is <= rA
close all
hold on
plot3(xA,yA,zA,'r+', 'Linewidth', 3);
plot3(x(inrA),y(inrA),z(inrA),'k.');
plot3(x(~inrA),y(~inrA),z(~inrA),'.','Color',0.8+[0 0 0]);
axis equal