PhotoNet+: Outlier-resilient coverage maximization in visual sensing applications

This demonstration illustrates a service for collection and delivery of images, in participatory camera networks, to maximize coverage while removing outliers (i.e., irrelevant images). Images, such as those taken by smart-phone users, represent an important and growing modality in social sensing applications. They can be used, for instance, to document occurrences of interest in participatory sensing campaigns, such as instances of graffiti on campus or invasive species in a park. In applications with a significant number of participants, the number of images collected may be very large. A key problem becomes one of data triage to reduce the number of images delivered to a manageable count, without missing important ones. In prior work, the authors presented a service, called PhotoNet [2], that reduces redundancy among delivered images by maximizing diversity. The current work significantly extends our previous effort by recognizing that diversity maximization often leads to selection of outliers; images that are visually different but not necessarily relevant, which in fact reduces the quality of the delivered image pool. We demonstrate a new prioritization technique that maximizes diversity among delivered pictures, while also reducing outliers.