Visualizing the Wavenumber Content of a Point Pattern

point patterns
spectral analysis
Authors
Affiliations

Jake P Grainger

EPFL

Tuomas Rajala

Natural Resources Institute Finland

David J Murrell

UCL

Sofia Olhede

EPFL

Published

November 1, 2023

Doi

Abstract

Spatial point patterns are a commonly recorded form of data in ecology, medicine, astronomy, criminology, epidemiology and many other application fields. One way to understand their second order dependence structure is via their spectral density function. However, unlike time series analysis, for point patterns such approaches are currently underutilized. In part, this is because the interpretation of the spectral representation of the underlying point processes is challenging. In this letter, we demonstrate how to band-pass filter point patterns, thus enabling us to explore the spectral representation of point patterns in space by isolating the signal corresponding to certain sets of wavenumbers.

Fig 2: Illustration of the signal boosting obtained by low-pass filtering a point process. Darker shades indicate higher values in the contour plots, and the range is shared for the filtered processes.