Citizens as Sensors: The World of Volunteered Geography

Michael F. GoodchildGeoJournal (2007) 69:211–221

DOI 10.1007/s10708-007-9111-y

Presented by:Group 1:

Sampada kogje Pavithra Panneerselvam

Evolving World of VGI

• What is VGI?– Volunteered Geographic Information – special case of user-

generated content.• Who do it? – Citizens that willing to contribute information about any

geographic location• What information is shared?– Information about a place, landmark, building, etc.– Pictures taken at a place– Routes that connect different parts of a city– A lot more!

Wikimapia

OpenStreetMap

Flickr

Emerging Technologies

• Web 2.0: Allows users to post information in the form of content, pictures, videos and VGI.

• Geo-referencing: Captures users’ geographic information (such as Lat/Long, points on map).

• Geo-tags: Code that can be inserted into information to note appropriate geographic location.

• GPS: Stand-alone and in-dash GPS devices compares current location of vehicles with the digital street maps and provide faster routes.

• Graphics: High-quality 2-D and 3-D graphics support most of the applications.

Problem Statement

• What drives people to do provide VGI?• How accurate are the results?• Will they threaten individual privacy?• How can they augment more conventional

sources?

Motivation for VGI

• World mapping is declining - Governments not willing to pay for increasing costs of mapping and consider map users as sources of income.

• Remote sensing replaced mapping – satellites not able to sense many phenomena with remote sensing.

• Patchwork coverage: Collection of individuals that act independently and respond to needs of local communities create a patchwork coverage. With appropriate tools and internet, the patchworks are integrated removing inconsistencies and distributed over the web.

Humans as Sensors

• Three types of sensor networks:– Most fit in this first category that includes sensors used for

specific measurements, traffic movement etc. – Less commonly used category include physical sensors carried

by humans, vehicles or animals. – Most interesting category: Humans

• Five senses• Intelligence to compile and interpret what they sense• Free to move around anywhere• Available in abundant (over 6 million)

• Citizen Science: Communities or networks of citizens who act as observers

Types of Contributions• Wikimapia – Users share information about all places around the globe. • Companies that produced digital maps relied on networks of local

observers and paid them.• Military personnel are potential sources of information about battlefield

conditions. • Human population in areas affected by natural disasters such as

tsunami, hurricanes, etc report conditions through mobile phone using voice, text or pictures. VGI may not be used in many of these cases but reports obtained from humans are useful in providing VGIs.

• Motivating Factors:– Self-promotion– Share information to only a close group of people – which later is

available to all– Personal satisfaction

Accuracy

• Traditional mapping agencies had standards which over the years changed.

• Google had no reputation in geography domain. (Google Earth’s imagery over the University of California campus was mis-registered by 20 miles)

• VGI is often called asserted geographic information as the content is asserted by its creator without any references, citations, or authority.

Accuracy is still an issue!

Major Contributions of the Paper

• Coins the term Citizen Sensors that describe individuals who "sense" geographic information and who use this information to construct "elaborate mental understanding of the areas where [they] live and work.

• Outlines how development of mobile devices, increased broadband access, and the emergence of Web 2.0 technologies further allow for VGI to be shared widely.

Concepts to be Refined

• Accuracy of VGI data • Individual privacy in VGI

Further Reading

• Goodchild, M. 2007a. Citizens as voluntary sensors: spatial data infrastructure in the world of Web 2.0. International Journal of Spatial Data Infrastructure Research 2:24-32.

• Wiersma, YF. 2010. Birding 2.0: Citizen Science and Effective Monitoring in the Web 2.0 World. Avian Conservation and Ecology 5 (2): 13.

Thank You!