Error Propagation in Satellite Multi-image Geometry

TL;DR

This paper investigates geospatial errors in satellite-derived digital surface models, introducing a new algorithm that uses satellite pose covariance to improve global positioning accuracy and predicting local errors validated against LiDAR data.

Contribution

It presents a novel algorithm incorporating satellite pose covariance for enhanced global georeferencing of DSMs from satellite images.

Findings

Covariance-based weighting reduces global position uncertainty.

Predicted local errors align well with LiDAR ground truth.

Method improves accuracy of satellite-derived DSMs.

Abstract

This paper describes an investigation of the source of geospatial error in digital surface models (DSMs) constructed from multiple satellite images. In this study the uncertainty in surface geometry is separated into two spatial components; global error that affects the absolute position of the surface, and local error that varies from surface point to surface point. The global error component is caused by inaccuracy in the satellite imaging process, mainly due to uncertainty in the satellite position and orientation (pose) during image collection. A key result of the investigation is a new algorithm for determining the absolute geoposition of the DSM that takes into account the pose covariance of each satellite during image collection. This covariance information is used to weigh the evidence from each image in the computation of the global position of the DSM. The use of covariance information significantly decreases the overall uncertainty in global position. The paper also describes an approach to the prediction of local error in the DSM surface. The observed variance in surface position within a single stereo surface reconstruction defines the local horizontal error. The variance in the fused set of elevations from multiple stereo pairs at a single DSM location defines the local vertical error. These accuracy predictions are compared to ground truth provided by LiDAR scans of the same geographic region of interest.