Open Access Battle Damage Detection via Pixel-Wise T-Test on Sentinel-1 Imagery

TL;DR

This paper presents the Pixel-Wise T-Test (PWTT), an open access, reproducible, and explainable method for detecting building damage from synthetic aperture radar imagery, providing near-real-time estimates for conflict zones.

Contribution

The paper introduces PWTT, a simple, lightweight statistical change detection method that rivals deep learning approaches in accuracy using open data and is deployable within Google Earth Engine.

Findings

Achieves building-level accuracy with AUC up to 0.88

Operates entirely within Google Earth Engine

Provides near-real-time damage estimates for conflict zones

Abstract

In the context of recent, highly destructive conflicts in Gaza and Ukraine, reliable estimates of building damage are essential for an informed public discourse, human rights monitoring, and humanitarian aid provision. Given the contentious nature of conflict damage assessment, these estimates must be fully reproducible, explainable, and derived from open access data. This paper introduces a new method for building damage detection-- the Pixel-Wise T-Test (PWTT)-- that satisfies these conditions. Using a combination of freely-available synthetic aperture radar imagery and statistical change detection, the PWTT generates accurate conflict damage estimates across a wide area at regular time intervals. Accuracy is assessed using an original dataset of over half a million labeled building footprints spanning 12 cities across Ukraine, Palestine, Syria, and Iraq. Despite being simple and lightweight, the algorithm achieves building-level accuracy statistics (AUC=0.88 across Ukraine, 0.81 in Gaza) rivalling state of the art methods that use deep learning and high resolution imagery. The workflow is open source and deployed entirely within the Google Earth Engine environment, allowing for the generation of interactive Battle Damage Dashboards for Ukraine and Gaza that update in near-real time, allowing the public and humanitarian practitioners to immediately get estimates of damaged buildings in a given area.