Humans as Sensors

The paper by Goodchild provides an overview of the various enabling factors that have led to the success of VGIS. I found the concept of “Humans as sensors” to be particularly interesting. I feel that this is has been the primary driving force behind VGIS services like Wikimapia, Openstreet Maps and even Google Maps. When maps started becoming digital, one of the primary challenges was to gather enough data to represent an area at different scales. This problem was not particularly profound in case of paper maps which were produced at certain discrete scales only. To gather enough data for digital maps, mass public participation became inevitable. Collecting so much data at different granularity levels was made possible only because people with varying degree of knowledge about an area started to contribute to services like OpenStreet Maps; overtime generating enough information to provide a fairly complete “patchwork”. Despite all the public effort, Google Maps for India have been criticized to be incomplete, incorrect and even non-existent in certain cases. As a response, Google has organised an event called Mapathon 2013 (from 12th of February 2013 to the 25th of March 2013) in India. The event aims to incentivise the process of adding geographic information to Google Maps by giving out attractive prices to the top editors.

When it comes to the use of VGIS in case of emergency or disaster situations, where traditional data collection can become too slow to be useful, Ushahidi deserves special mention. “Ushahidi (Swahili for “testimony” or “witness”) created a website ( in the aftermath of Kenya’s disputed 2007 presidential election that collected eyewitness reports of violence sent in by email and text-message and placed them on a Google Maps map” (Wikipedia). A visit to the Wikipedia entry for Ushahidi reveals several crisis situations where similar solutions based on the Ushahidi platform proved to be helpful. I also encourage a visit to the Ushahidi website ( to understand the wide range of technological support that it provides to build crisis/disaster mapping portals.

– Dipto Sarkar

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