The Impact of Federated Learning on Distributed Remote Sensing Archives

TL;DR

This paper empirically evaluates federated learning strategies for remote sensing image classification, addressing data heterogeneity challenges and analyzing the impact of model architecture and communication costs.

Contribution

It systematically compares FL algorithms like FedAvg, FedProx, and BSP on remote sensing data with non-IID distributions, providing insights into their performance and trade-offs.

Findings

FedProx outperforms FedAvg with deeper CNNs under data heterogeneity.

BSP achieves near-centralized accuracy but with higher communication costs.

LeNet offers the best accuracy-communication balance for the dataset.

Abstract

Remote sensing archives are inherently distributed: Earth observation missions such as Sentinel-1, Sentinel-2, and Sentinel-3 have collectively accumulated more than 5 petabytes of imagery, stored and processed across many geographically dispersed platforms. Training machine learning models on such data in a centralized fashion is impractical due to data volume, sovereignty constraints, and geographic distribution. Federated learning (FL) addresses this by keeping data local and exchanging only model updates. A central challenge for remote sensing is the non-IID nature of Earth observation data: label distributions vary strongly by geographic region, degrading the convergence of standard FL algorithms. In this paper, we conduct a systematic empirical study of three FL strategies -- FedAvg, FedProx, and bulk synchronous parallel (BSP) -- applied to multi-label remote sensing image classification under controlled non-IID label-skew conditions. We evaluate three convolutional neural network (CNN) architectures of increasing depth (LeNet, AlexNet, and ResNet-34) and analyze the joint effect of algorithm choice, model capacity, client fraction, client count, batch size, and communication cost. Experiments on the UC Merced multi-label dataset show that FedProx outperforms FedAvg for deeper architectures under data heterogeneity, that BSP approaches centralized accuracy at the cost of high sequential communication, and that LeNet provides the best accuracy-communication trade-off for the dataset scale considered.