Global Assists Local: Effective Aerial Representations for Field of View Constrained Image Geo-Localization

Abstract

When we humans recognize places from images, we not only infer about the objects that are available but even think about landmarks that might be surrounding it. Current place recognition approaches lack the ability to go beyond objects that are available in the image and hence miss out on understanding the scene completely. In this paper, we take a step towards holistic scene understanding. We address the problem of image geo-localization by retrieving corresponding aerial views from a large database of geotagged aerial imagery. One of the main challenges in tackling this problem is the limited Field of View (FoV) nature of query images which needs to be matched to aerial views which contain 360°FoV details. State-of-the-art method DSM-Net [19] tackles this challenge by matching aerial images locally within fixed FoV sectors. We show that local matching limits complete scene understanding and is inadequate when partial buildings are visible in query images or when local sectors of aerial images are covered by dense trees. Our approach considers both local and global properties of aerial images and hence is robust to such conditions. Experiments on standard benchmarks demonstrates that the proposed approach improves top-1% image recall rate on the CVACT [9] data-set from 57.08% to 77.19% and from 61.20% to 75.21% on the CVUSA [28] data-set for 70°FoV. We also achieve state-of-the art results for 90°FoV on both CVACT [9] and CVUSA [28] data-sets demonstrating the effectiveness of our proposed method.