Investigating the Feasibility of Geo-Tagged Photographs as Sources of Land Cover Input Data

Vyron Antoniou,Flavio Lupia,Linda See,Steffen Fritz,Cidália Fonte,Jacinto Estima,Giles Foody,Marco Minghini,Jamal Arsanjani

doi:10.3390/ijgi5050064

Abstract

Geo-tagged photographs are used increasingly as a source of Volunteered Geographic Information (VGI), which could potentially be used for land use and land cover applications. The purpose of this paper is to analyze the feasibility of using this source of spatial information for three use cases related to land cover: Calibration, validation and verification. We first provide an inventory of the metadata that are collected with geo-tagged photographs and then consider what elements would be essential, desirable, or unnecessary for the aforementioned use cases. Geo-tagged photographs were then extracted from Flickr, Panoramio and Geograph for an area of London, UK, and classified based on their usefulness for land cover mapping including an analysis of the accompanying metadata. Finally, we discuss protocols for geo-tagged photographs for use of VGI in relation to land cover applications.

Highlights

Volunteered Geographic Information (VGI) refers to the provision of location-based information by volunteers [1], where online collaborative mapping has made OpenStreetMap (OSM) one of the most successful examples of spatial data collection by citizens [2]
A novel method was developed by Rattenbury et al [22] to detect event and place semantics from the distribution and frequency of tags from Flickr images in the San Francisco Bay area, outperforming other similar methods, while Chen and Roy [23] used geo-tagged photographs to detect aperiodic events, using wavelets to first filter out noise
The scope of this paper is to qualitatively evaluate the metadata available for geo-tagged photographs against the use case requirements, an extra step was taken to calculate the quantity of tags and descriptions available, which are associated with the photographs

Summary

Introduction

Volunteered Geographic Information (VGI) refers to the provision of location-based information by volunteers [1], where online collaborative mapping has made OpenStreetMap (OSM) one of the most successful examples of spatial data collection by citizens [2]. Much less work has been focused on the use of geo-tagged photographs as a source of VGI [11], yet they represent a substantial and growing source of volunteered information, e.g., from online repositories such as Flickr, Panoramio and Geograph, as well as public social media platforms, such as Instagram. Similar studies have appeared using geo-tagged images to find areas of touristic interest in Australia, Hong Kong, Italy and Switzerland, as well as extracting the behavioral patterns of tourists by identifying the main spatio-temporal trajectories taken by visitors [16,17,18,19,20]. Four types of spatio-temporal clusters (stationary, reappearing, occasional and regular moving) were found in Flickr photographs from Switzerland [19], where the authors combined these patterns with semantic interpretation of the text (i.e., tags from the photographs) and information from external data sources (i.e., geo-tagged Wiki pages). Geo-tagged photographs have been used to detect social events such as soccer matches, concerts, parades and festivals [24,25,26] while tourist photographs have been used to reconstruct urban areas [27,28]

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