Scene Signatures: Localised and Point-less Features for Localisation

Abstract

This paper is about localising across extreme lighting and weather conditions. We depart from the traditional point-feature-based approach since matching under dramatic appearance changes is a brittle and hard. Point-feature detectors are rigid procedures which pass over an image examining small, low-level structure such as corners or blobs. They apply the same criteria to all images of all places. This paper takes a contrary view and asks what is possible if instead we learn a bespoke detector for every place. Our localisation task then turns into curating a large bank of spatially indexed detectors and we show that this yields vastly superior performance in terms of robustness in exchange for a reduced but tolerable metric precision. We present an unsupervised system that produces broad-region detectors for distinctive visual elements, called scene signatures, which can be associated across almost all appearance changes. We show, using 21 km of data collected over a period of 3 months, that our system is capable of producing metric estimates from night-to-day or summer-to-winter conditions.