How to get random points from upper semisphere
2 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Mojtaba Mohareri
am 19 Aug. 2020
Kommentiert: Mojtaba Mohareri
am 19 Aug. 2020
Hello eveyone,
I use this code to get random points from a sphere with radius 5:
clear all
clc
fullFileName = fullfile(pwd, 'DataPoints.txt')
% Open a text file.
fileHandle = fopen(fullFileName, 'wt');
% Write out the things we want to write out.
rng(0,'twister')
rvals = pi*rand(100,1)+pi/2;
azimuth = 2*pi*rand(100,1);
[x,y,z] = sph2cart(azimuth,rvals,5);
figure
plot3(x,y,z,'.')
axis equal
fprintf(fileHandle, '{%f, %f ,%f},',[x,y,z]');
fprintf(fileHandle, '[%f, %f ,%f],',[x,y,z]');
fprintf(fileHandle, '%f, %f , %f;',[x,y,z]');
% Close the file.
fclose(fileHandle);
% Open it in notepad (Windows OS only)
winopen(fullFileName);
, but I want to have random points from upper semisphere with this radius.
Thanks in advance.
0 Kommentare
Akzeptierte Antwort
Weitere Antworten (1)
Bruno Luong
am 19 Aug. 2020
Bearbeitet: Bruno Luong
am 19 Aug. 2020
Your code won't generate uniform point on half sphere, there is a bigger density on the north pole (try to generate with 10000 points you'll see).
A better approach would be
radius = 5;
xyz = randn(3,100);
xyz = xyz .* (radius ./ sqrt(sum(xyz.^2,1)));
x = xyz(1,:);
y = xyz(2,:);
z = abs(xyz(3,:));
3 Kommentare
Bruno Luong
am 19 Aug. 2020
You have very old matlab version, replace with
xyz = bsxfun(@times, xyz, radius ./ sqrt(sum(xyz.^2,1)));
Siehe auch
Kategorien
Mehr zu Creating and Concatenating Matrices finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!