It’s About Time: The Temporal Dimension in VGI

Michael F. GoodchildUniversity of California

Santa Barbara

Time and geographic information• Maps emphasize the static aspects of

geographyroads ri ers terrain cities ho ses– roads, rivers, terrain, cities, houses

– in order to justify the high cost of map production– by making maps useful for as long as possibleby making maps useful for as long as possible

• But geography is dynamic– processes modify the human and physicalprocesses modify the human and physical

landscapes– humans move– events occur– emergencies develop

Inherited by GIS• The first GIS inputs were from maps

– accurate GPS is recentTh fi t GIS li ti b d• The first GIS applications were map-based– the map metaphor

GIS as a container of maps– GIS as a container of maps– doing things with maps that humans found too

tedious, error-prone, or expensive to do by hand, p , p y• Given enough time and resources, a perfect

map can be produced– still waiting

Neogeography• The cost of mapping has been driven

essentially to zeroS ft k t• Software makes everyone an expert cartographerMaps can be made of anything at any time• Maps can be made of anything, at any time, by anyone– single-purpose maps– single-purpose maps– personal maps

• location-based services

– maps of where things are right now

Who?• Everyone

– the citizen, the community, the general publict h– amateurs, neogeographers

– military personnel in the war zone– participating individuals– participating individuals

• Voluntarily– consciouslyconsciously– without tangible reward

• A social networkA social network

What?• Geographic information

– information relating properties to locations on or near the Earth’s surfacenear the Earth s surface

• Beyond the map– 3D transitory or dynamic personal– 3D, transitory or dynamic, personal

• Unary– information about placesinformation about places

• Binary– information about pairs of placesinformation about pairs of places

• distance, direction, travel cost, travel time, flow, interaction, network linkages

The information hierarchy• Data• Information• Knowledge• Understanding• Wisdom• All of the above

– amateur synthesis• How can amateurs create not just geographic

information but geography knowledge, understanding, and even wisdom?

Why?• Many types of geographic information are not

suitable for remote sensingstreet names– street names

– population density– incomeincome

• Must come from local people– and there are lots of peopleand there are lots of people

Tracks inferred from Flickr postings (http://www cs cornell edu/~crandall/papers/mapping09www pdf)(http://www.cs.cornell.edu/~crandall/papers/mapping09www.pdf)

See also http://www.flickr.com/photos/walkingsf/sets/72157624209158632/

The coverage problem• Experts are thin on the ground• Suppose an expert takes time t to map an

area a• Suppose there are n such teams• The total time required to map an area A is

At/an

Time and authoritative mapping• Tom Dibblee

– geologic mapping of California1 t 400– 1 expert, ~400 maps

• 1:24,000 to 1:62,500

– ~10 maps per year0 aps pe yea– the average map 20 years old

The VGI advantage• A set of 40 adequately trained amateurs

could achieve in 1 year what took Dibblee 40 yearsyears

• We have 7 billion intelligent observers on the planetplanet

Time-critical community mapping• TCCM• To map fast-changing phenomena• To maintain the currency of mapping• To map during emergencies• It’s about time

LA Ti M 8 2009LA Times May 8 2009

Hits Source595673 Jesusita Fire (Ethan)

188308 SBC Jesusita Fire Santa Barbara, CA (Robert O'Connor - fire news blog)

89214 Jesusita Fire Map (Randy - Independent.com)

67525 Jesusita Fire in Santa Barbara - LA Times map (Los Angeles Times)67525 Jesusita Fire in Santa Barbara - LA Times map (Los Angeles Times)

27777 Map of burned homes in Santa Barbara (Los Angeles Times)

26330 Jesusita Fire Evacuation Areas: Approximation (COSB)

25454 Santa Barbara 'Jesusita Fire' (ABC7 Eyewitness News)

19592 Jesusita Fire - Santa Barbara (lanewspace)

2446 Santa Barbara Damaged Homes 2008 (Los Angeles Times, note: mapped for comparison with Jesusita)

2048 Jesusita Fire (longhairedhippy)

1314 Santa Barbara Fire Evacuation (Gary);

962 Jesusita Fire in Santa Barbara (ABC30 Action News)962 Jesusita Fire in Santa Barbara (ABC30 Action News)

788 Wildfire ~ Santa Barbara (Buffalo)

505 Closure map - Jesusita Fire in Santa Barbara (Los Angeles Times)

18

461 Untitled (Matthew, note: discovered via google.com.mx);

396 Jesusita Fire Structure Damage (Paul Bartsch);

Linus’s Law• Linus Torvald

– how to assure software quality?h l t f l i– have lots of people review

– cf Wikipedia• Popular/populated places more accurate• Popular/populated places more accurate

than remote places• The power of geographic context• The power of geographic context

– Tobler’s First Law– “All things are related but nearby things are moreAll things are related but nearby things are more

related than distant things”– horizontal and vertical context

www.flickr.com

wikimapia.org

How does VGI stack up?• VGI is comparatively new

– much authoritative information was collected long agoago

– VGI is generally more current– VGI uses more recent technologyG uses o e ece ec o ogy

• compare GPS to traditional surveying

• VGI often beats authoritative mapping

nationalmap.gov

Quality of TCCM• Better imperfect information now

– than no information now and perfect information laterlater

• False positives are more acceptable than false negativesfalse negatives

The VGI life cycle• Will people be as interested in updating VGI

as in creating it in the first place?H ill VGI i th l t ?• How will we preserve VGI in the long term?– will we preserve earlier pictures of the world

or replace them with new pictures?– or replace them with new pictures?• How will we preserve the exaflood?

Time and VGI• The case for VGI is most compelling when

the temporal dimension is consideredTi iti l it i• Time-critical community mapping– a realistic solution to the dissemination of

information during emergenciesinformation during emergencies• All geographic information deteriorates

through timethrough time– at varying rates

• from geologic to wildfire speed

– fast acquisition of geographic information is critical to its accuracy and value