Iterative Residual Fitting for Spherical Harmonic Transform of Band-Limited Signals on the Sphere: Generalization and Analysis

TL;DR

This paper introduces a generalized iterative residual fitting method for computing spherical harmonic transforms of band-limited signals on the sphere, accommodating irregular sampling and improving accuracy through multiple passes.

Contribution

It proposes a novel IRF technique that generalizes SHT computation for irregular samples and introduces a multi-pass approach for enhanced accuracy.

Findings

Multi-pass IRF improves SHT accuracy.

Method supports irregular sampling schemes.

Numerical experiments validate effectiveness.

Abstract

We present the generalized iterative residual fitting (IRF) for the computation of the spherical harmonic transform (SHT) of band-limited signals on the sphere. The proposed method is based on the partitioning of the subspace of band-limited signals into orthogonal subspaces. There exist sampling schemes on the sphere which support accurate computation of SHT. However, there are applications where samples~(or measurements) are not taken over the predefined grid due to nature of the signal and/or acquisition set-up. To support such applications, the proposed IRF method enables accurate computation of SHTs of signals with randomly distributed sufficient number of samples. In order to improve the accuracy of the computation of the SHT, we also present the so-called multi-pass IRF which adds multiple iterative passes to the IRF. We analyse the multi-pass IRF for different sampling schemes and for different size partitions. Furthermore, we conduct numerical experiments to illustrate that the multi-pass IRF allows sufficiently accurate computation of SHTs.