# Drawing a 3D Poisson Point Process with intensity $\lambda$

Can anyone suggest me a way of drawing a 3-dimensional Poisson Point Process (PPP) with intensity $\lambda$ in Mathematica. The points are located only in a half sphere. The 3-dimensional ball of radius $r$ is located in the origin. Let the radius $r$ be equal to 1.

Mathematica has RandomPoint for picking a uniformly distributed point inside the specified region. As the average number of points for a uniform PPP in a bound region is proportional to it's volume, we have to variate PoissonDistribution with a given parameter and obtain this number of random points. All that is left is to draw it all together.

R = ImplicitRegion[
x^2 + y^2 + z^2 <= 1,
{{x, 0, ∞}, y, z}
];
λ = 50;

pts = RandomPoint[
R,
RandomVariate[
PoissonDistribution[λ*Integrate[1, {x, y, z} ∈ R]]
]
];

Show[{
RegionPlot3D[
R,
PlotStyle -> Opacity[0.2]
],
Graphics3D[
Point[pts]
]
}]

This code will produce the next picture:

• What about the location (x, y, z of these points? Can I know that too?) – Adil Apr 9 '18 at 12:41
• @Adil Those are stored in pts (check the documentation for RandomPoint). – Andrew S. Apr 9 '18 at 14:38