How to generate a random point in the volume of a cylinder
16 visualizaciones (últimos 30 días)
Mostrar comentarios más antiguos
Musa Mustapha
el 24 de Jun. de 2019
Comentada: John D'Errico
el 24 de Jun. de 2019
I have a cylinder in three-dimensions with a long-axis defined by the endpoints ?1 and ?2, and radius ?. p1=[0.5, 0.3, 1]; p2=[0.4, 0.5, 0.7]; R=0.5;
2 comentarios
James Tursa
el 24 de Jun. de 2019
What have you done so far? What specific problems are you having with your code? Do you know how to generate a random point inside a circle? Do you know how to rotate vectors in 3D space?
Respuesta aceptada
John D'Errico
el 24 de Jun. de 2019
Since you already have an answer posted... Pretty easy, actually. So two points that define the ends of the cylinder, and a known radius.
p1=[0.5, 0.3, 1];
p2=[0.4, 0.5, 0.7];
R=0.5;
N = 100000; % # of points to generate
First, generate a random point along the cylinder axis. The vector that defines the axis is given by:
axialvec = p2 - p1;
axialvec = axialvec/norm(axialvec);
axialpoints = p1 + (p2 - p1).*rand(N,1);
Next, we work in a cylindrical coordinate system around the centerline. Generate points at random inside a circle of radius R, in TWO dimensions.
circr = sqrt(rand(N,1))*R;
circtheta = rand(N,1)*2*pi;
circpoints = [cos(circtheta).*circr,sin(circtheta).*circr];
Rotate the points into the plane perpendicular to the axis.
axnull = null(axialvec);
points = axialpoints + circpoints*axnull.';
And plot.
plot3(points(:,1),points(:,2),points(:,3),'.')
grid on
box on
axis equal
Rotate it around to convince yourself the points form a cylinder.
0 comentarios
Más respuestas (0)
Ver también
Categorías
Más información sobre Spectral Measurements en Help Center y File Exchange.
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!