document: A game based approach to assign geographical relevance to web images Geographical context is very important for images . Millions of images on the Web have been already assigned latitude and longitude information . Due to the rapid proliferation of such images with geographical context , it is still difficult to effectively search and browse them , since we do not have ways to decide their relevance . In this paper , we focus on the geographical relevance of images , which is defined as to what extent the main objects in an image match landmarks at the location where the image was taken . Recently , researchers have proposed to use game based approaches to label large scale data such as Web images . However , previous works have not shown the quality of collected game logs in detail and how the logs can improve existing applications . To answer these questions , we design and implement a Web-based and multi-player game to collect human knowledge while people are enjoying the game . Then we thoroughly analyze the game logs obtained during a three week study with 147 participants and propose methods to determine the image geographical relevance . In addition , we conduct an experiment to compare our methods with a commercial search engine . Experimental results show that our methods dramatically improve image search relevance . Furthermore , we show that we can derive geographically relevant objects and their salient portion in images , which is valuable for a number of applications such as image location recognition .
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