With the widespread availability of cellphones and cameras that have GPS capabilities, it is common for images being uploaded to the Internet today to have GPS coordinates associated with them. In addition to research that tries to predict GPS coordinates from visual features, this also opens up the door to problems that are conditioned on the availability of GPS coordinates. In this work, we tackle the problem of performing image classification with location context, in which we are given the GPS coordinates for images in both the train and test phases. We explore different ways of encoding and extracting features from the GPS coordinates, and show how to naturally incorporate these features into a Convolutional Neural Network (CNN), the current state-of-the-art for most image classification and recognition problems. We also show how it is possible to simultaneously learn the optimal pooling radii for a subset of our features within the CNN framework. To evaluate our model and to help promote research in this area, we identify a set of location-sensitive concepts and annotate a subset of the Yahoo Flickr Creative Commons 100M dataset that has GPS coordinates with these concepts, which we make publicly available. By leveraging location context, we are able to achieve almost a 7 gain in mean average precision.
There is a large body of work that focuses on the problem of image geolocation, such as geolocating static cameras @cite_28 , city-scale location recognition @cite_6 , im2gps @cite_24 @cite_34 , place recognition @cite_13 @cite_12 , landmark recognition @cite_39 @cite_23 @cite_29 @cite_26 , geolocation leveraging geometry information @cite_39 @cite_7 @cite_1 @cite_17 , and geolocation with graph-based representations @cite_41 . More recent works have also tried to supplement images with corresponding data @cite_14 @cite_19 @cite_4 @cite_36 @cite_10 , such as digital elevation maps and land cover survey data, which we draw inspiration from in constructing our features. In contrast to these works, we assume we are given GPS coordinates, and use this information to help improve image classification performance.
@cite_41 @cite_36 @cite_29 @cite_10 @cite_4 @cite_39 @cite_23 @cite_17 @cite_26 @cite_7 @cite_28 @cite_6 @cite_19 @cite_34 @cite_12 @cite_14 @cite_1 @cite_24 @cite_13
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In this chapter, we explore the task of global image geolocalization—estimating where on the Earth a photograph was captured. We examine variants of the “im2gps” algorithm using millions of “geotagged” Internet photographs as training data. We first discuss a simple to understand nearest-neighbor baseline. Next, we introduce a lazy-learning approach with more sophisticated features that doubles the performance of the original “im2gps” algorithm. Beyond quantifying geolocalization accuracy, we also analyze (a) how the nonuniform distribution of training data impacts the algorithm (b) how performance compares to baselines such as random guessing and land-cover recognition and (c) whether geolocalization is simply landmark or “instance level” recognition at a large scale. We also show that geolocation estimates can provide the basis for image understanding tasks such as population density estimation or land cover estimation. This work was originally described, in part, in “im2gps” [9] which was the first attempt at global geolocalization using Internet-derived training data. The recent availability of geo-tagged images and rich geospatial data has inspired a number of algorithms for image based geolocalization. Most approaches predict the location of a query image by matching to ground-level images with known locations (e.g., street-view data). However, most of the Earth does not have ground-level reference photos available. Fortunately, more complete coverage is provided by oblique aerial or “bird's eye” imagery. In this work, we localize a ground-level query image by matching it to a reference database of aerial imagery. We use publicly available data to build a dataset of 78K aligned crossview image pairs. The primary challenge for this task is that traditional computer vision approaches cannot handle the wide baseline and appearance variation of these cross-view pairs. We use our dataset to learn a feature representation in which matching views are near one another and mismatched views are far apart. Our proposed approach, Where-CNN, is inspired by deep learning success in face verification and achieves significant improvements over traditional hand-crafted features and existing deep features learned from other large-scale databases. We show the effectiveness of Where-CNN in finding matches between street view and aerial view imagery and demonstrate the ability of our learned features to generalize to novel locations. With recent advances in mobile computing, the demand for visual localization or landmark identification on mobile devices is gaining interest. We advance the state of the art in this area by fusing two popular representations of street-level image data - facade-aligned and viewpoint-aligned - and show that they contain complementary information that can be exploited to significantly improve the recall rates on the city scale. We also improve feature detection in low contrast parts of the street-level data, and discuss how to incorporate priors on a user's position (e.g. given by noisy GPS readings or network cells), which previous approaches often ignore. Finally, and maybe most importantly, we present our results according to a carefully designed, repeatable evaluation scheme and make publicly available a set of 1.7 million images with ground truth labels, geotags, and calibration data, as well as a difficult set of cell phone query images. We provide these resources as a benchmark to facilitate further research in the area. The recent availability of large amounts of geotagged imagery has inspired a number of data driven solutions to the image geolocalization problem. Existing approaches predict the location of a query image by matching it to a database of georeferenced photographs. While there are many geotagged images available on photo sharing and street view sites, most are clustered around landmarks and urban areas. The vast majority of the Earth's land area has no ground level reference photos available, which limits the applicability of all existing image geolocalization methods. On the other hand, there is no shortage of visual and geographic data that densely covers the Earth - we examine overhead imagery and land cover survey data - but the relationship between this data and ground level query photographs is complex. In this paper, we introduce a cross-view feature translation approach to greatly extend the reach of image geolocalization methods. We can often localize a query even if it has no corresponding ground level images in the database. A key idea is to learn the relationship between ground level appearance and overhead appearance and land cover attributes from sparsely available geotagged ground-level images. We perform experiments over a 1600 km2 region containing a variety of scenes and land cover types. For each query, our algorithm produces a probability density over the region of interest.