The Geospatial Web: A State of the Art Report

Michael F. GoodchildUniversity of California

Santa Barbara

The Geospatial Web• GeoWeb, Spatial Web• An integration of sensors, servers, and users sharing

geospatial data that is often dynamic and near real-time, and fully interoperable

• Geospatial data– georeferenced descriptions of the Earth’s surface and near-

surface– <x,z>– often aggregated

• statements about lines, areas, volumes

• Geospatial technologies– geographic information systems (GIS), GPS, remote

sensing, RFID

The mashup• New information obtained by linking through

geographic location– visual or logical

fundrace.huffingtonpost.com

Land classification• Land cover, land use, soils, wetlands,…• Incompatible classification schemes

– European Union INSPIRE project– harmonizing classifications across 27 member

states

Georeferencing• The ability to determine location quickly and

easily– most people do not know their latitude and

longitude– what is at:

latitude 34 deg 24 min 42.7 seconds north, 119 deg 52 min 14.4 sec west

236150m easting, 3811560m northing, UTM Zone 11 Northern Hemisphere

National Grid reference 11SKU36151156909 West Campus Lane, Goleta, CA 93117, USA

– the informal world of human discourse meets the formal world of geographic coordinates

http://www.thesalmons.org/lynn/wh-greenwich.html

Digital gazetteers• Alexandria Digital Library (ADL)• GeoNet Names Server (NGA)• Geographic Names Info Sys (USGS)• Thesaurus of Geographic Names (Getty)• Electronic Cultural Atlas Initiative (ECAI)• Expedia, Google, Mapquest, et al.

(underlying, not explicitly accessible)

Digital Gazetteer - Basics

(controlled vocabulary)

Courtesy L. Hill (ADL Gazetteer Team, Feb 2002)

ADEPT, Smith, October 1999

Place-based information challenge

Metadata<!ENTITY % geographic-coordinate "(#PCDATA)"><!-- a geographic latitude in degrees north of the equator or

geographic longitude in degrees east of the Greenwichmeridian, e.g., "-121.025" -->

<!ELEMENT west_bounding_coor %geographic-coordinate;><!ELEMENT east_bounding_coor %geographic-coordinate;><!ELEMENT south_bounding_coor %geographic-coordinate;><!ELEMENT north_bounding_coor %geographic-coordinate;><!ELEMENT measurement_begin_date %calendar-date;>

Search Engines

Cataloging – Metadata Creation

Where is …?What’s there?

What happened there?

HarvestedWebpages

GIS datasets

Oral histories

Georeferencing by placename and by spatial footprint

Aerial photos

Books

Maps

DataPapers

Translation needed between placenames - locations

Gazetteers

Courtesy L. Hill (ADL Gazetteer Team, Feb 2002)

Challenges - conceptual• All attributes of place are multiple

– Names: Lake Tahoe, Tula Tulia– Types: Lake and/or Reservoir– Locations: Lake Tahoe ± Emerald Bay

• Place identity is subjective – a cognitive act– Culturally situated – ethnophysiography - Mark– Time-variant (names & types): Bonneville (now dry)– Evolving knowledge: sub-glacial lakes in Antarctica

Multiple attribution

Plate carre

Shapes

—— ESRI

~~~ USGS

Names

D’aowaga

Lake Tahoe

Sierra Lake

Types

+Water Body

- Lake

- Reservoir

Prioritization• Space first

– only one feature (of a given type) can occupy adefined space during a period of time

• Type second– types are approximate; features are multi-type

• Name third– names are intriguing but essentially arbitrary

Metrics• Geospatial

– point-in-polygon: distance to centroid– polygon-on-polygon: inter-areal overlap

(line features per se do not occur, by use of multihulls)

• Geotaxial (single taxonomy)– hierarchical distance, with “see” and “see also”

• Geonomial– stemming cross-match

How is geographic information created?• By authorities and their experts

– USGS– NGA– Ordnance Survey– military in many countries– state and local governments

• Disseminated to non-expert users– with restrictions– at cost of production or reproduction?– restrictions since 9/11

The formal naming process • U.S. Board on Geographic Names

– 1890• A hierarchy of boards from local to national

– composed of experts– no role for amateurs, the general public

• Need to standardize– to avoid confusion– postal delivery

The Waldseemüller map• St Dié-des-Vosges, 1507• A name that stuck

Volunteered geographic information (VGI)• A phenomenon of the 21st Century

– recent months• User-generated content• Collective intelligence• Crowdsourcing• Asserted information• The empowerment of millions of private citizens

– largely untrained– no obvious reward– no guarantee of truth– no authority

popvssoda.com

www.wikimapia.org

www.wikimapia.org

www.flickr.com

www.openstreetmap.org

Locations in text• Geoparsing• Geotagging with microformats

– mapping Wikipedia• Context-specific

– he was Shanghaied• Ambiguity

– clusters of geotags around Philadelphia NY• metacarta.com

Three types of sensor networks• Inert, fixed• Carried on moving objects

– vehicles– pedestrians

• asthma research• Human beings

– 6 billion intelligent sensors– informed observers– rich local knowledge– uplink technology

• broadband Internet• mobile phone

Citizen science• Networks of amateur observers

– possibly trained, skilled• Christmas Bird Count

– thousands of volunteer participants– protocols

• Project GLOBE– an international network of school children– reporting environmental conditions– central integration and redistribution

Participant populations• Open to all

– Wikimapia, Flickr• Trained or skilled volunteers

– Christmas Bird Count• School children

– GLOBE• Vehicle fleets

– Inrix• Farmers

– precision agriculture• Reversing the traditional top-down flow

Why do people do this?• Self-promotion

– exhibitionism– information remains identified with source

• compare Census• Altruism

– a belief that everything on the Web can be found– and will be used to good effect

• A desire to fill gaps in available data– especially in areas where data are not available– or where access is denied for security

• Sharing with friends, relatives– but accessible by all

The value of VGI• A significant contribution to geography

– enhancing our knowledge of the Earth– local focus– engaging citizens

• Many unresolved questions– trust, credibility– preservation– social psychology

Authority and assertion• Traditional mapping to high quality

– authoritative• The Wikipedia process

– anyone can edit– reviewed by volunteers– Google Maps

• The potential for hybrids– MapCorps

Towards a research agenda• Technical

– conflation– partial correction and update– SOA standards– metadata– quality control and assurance

• Social psychology– trust– who participates?

• engaging under-represented groups– local expertise– thematic expertise– privacy, access rights

Summary points• A rapidly changing world

– very strange to its former leaders• Engagement of the general public

– neogeographers– a willingness to volunteer

• Who are the experts?– we are all local experts

• A more dynamic view of geography– a tradition of leisurely activity

Summary points (2)• Where the informal world meets the formal

– conflation– interoperability

• New sources of geographic knowledge– place references in text– geotagging

• New concepts of data quality– user-generated