Implementing Digital Earth:A Research Agenda

Implementing Digital Earth:A Research Agenda

Michael F. Goodchild

University of California

Santa Barbara

Perspectives on Digital EarthPerspectives on Digital Earth

1. An immersive environment– “I believe we need a 'Digital Earth'. A multi-

resolution, three-dimensional representation of the planet, into which we can embed vast quantities of geo-referenced data.” U.S. Vice President Gore, 1/98

Spin, zoom, pan– "fly-by" technology

Immersive environmentsImmersive environments

Head-mounted devices Immersadesk The "cave" Standard computer displays

– 2D window on manipulable 3D objects– Nick Faust, Georgia Tech– SRI Digital Earth, Terravision– powerful processors, 3D graphics

Research challengesResearch challenges

Smooth zoom– 10km to 1m resolution– consistent data structures

smooth transitions to more detailed data color matches

– projections orthographic for the globe projected for local detail Georgia State: nested azimuthal projections

Research challenges (2)Research challenges (2)

Visualization– renderable data– non-renderable data

iconic representation indicating presence symbolic representation

– user-centered views reduce resolution in periphery avatar

Research challenges (3)Research challenges (3)

Local data, powerful processor– what is deliverable via the Internet?– bandwidth requirements– local data volume

1012 cells at 1m resolution

Software environments– VRML, GeoVRML– Open GL– triangular data structures

Research challenges (4)Research challenges (4)

Discrete global grids– for indexing and data representation

QTM (Geoffrey Dutton, Spatial Effects)– 8 triangles at level 0– recursive subdivision into 4 triangles– address is 1 base 8 digit and n base 4

digits– level 20 is roughly 1m resolution

Discrete global grid based on the Icosahedron (20 triangles, 1:4 recursive subdivision)

Ross Heikes and David Randall, Colorado State University

International Conference on Discrete Global GridsInternational Conference on Discrete Global Grids

Santa Barbara, California March 26-28, 2000 Abstracts due January 10, 2000 www.ncgia.ucsb.edu

Perspectives on Digital EarthPerspectives on Digital Earth

2. A metaphor for organizing information The geolibrary

– a library that is searchable by geographic location

– "what have you got about there?"– physically impossible but feasible in a

digital world

NRC reportNRC report

"Distributed Geolibraries: Spatial Information Resources"

www.nap.edu

Organizing information by locationOrganizing information by location

Information with a geographic footprint Organizational metaphors

– the desktop, office, workbench– the surface of the Earth

Research challengesResearch challenges

Defining footprints– fuzzy, vernacular

Mapping between georeferencing methods– the gazetteer

Search over a distributed archive– search engines– object-level metadata (OLM)– collection-level metadata (CLM)

CLM of the Alexandria Digital Library

Research challenges (2)Research challenges (2)

Approaches to CLM– by data type

ortho.mit.edu

– by area of the globe SRI's Digital Earth, IBM's WorldBoard

– the one stop shop www.fgdc.gov

– a new generation of search engines identifying footprints

Perspectives on Digital EarthPerspectives on Digital Earth

3. The Mother of All Databases (MOADB)

A distributed collection of knowledge about the Earth– transparent to the user– accessible through geolibrary mechanisms– supported by consistent protocols

Perspectives on Digital EarthPerspectives on Digital Earth

4. A collection of knowledge about the Earth's dynamics– the processes that create and modify the

landscape Dynamics or statics?

– most GIS data are cross-sectional time-slices providing facts

– understanding of the Earth must focus on processes

Bernhardus VareniusBernhardus Varenius

1622-1650 General geography

– the principles, processes Special geography

– the unique properties of places– the boundary conditions

A dynamic Digital EarthA dynamic Digital Earth

Simulations of past and future conditions

A library of simulation models– applied to local conditions represented by

data A tool with enormous educational value PCRaster demonstrations

– University of Utrecht, Peter Burrough

Three probabilities for Three probabilities for dispersiondispersionThree probabilities for Three probabilities for dispersiondispersion

1 Probability of individual reaching a given distance from the parent

2 Probability that habitat permits individual to establish

3 Probability that individual produces new offspring

UCELUCEL

Simple dispersion functionsSimple dispersion functionsSimple dispersion functionsSimple dispersion functions

Probability of establishment

UCELUCEL

Example of diffusion Example of diffusion modellingmodellingExample of diffusion Example of diffusion modellingmodelling

Dispersion of individuals over a space in which the resistance to movement is variable, individuals need to work together to colonize new areas

diffusion

Modelling uplift in Sabah, Malaysia.Modelling uplift in Sabah, Malaysia.

UCELUCEL

Over a period of several million years Over a period of several million years movement along the faults has movement along the faults has created long sediment-filled valleyscreated long sediment-filled valleys

Over a period of several million years Over a period of several million years movement along the faults has movement along the faults has created long sediment-filled valleyscreated long sediment-filled valleys

UCELUCEL

Faults

RelativeRelative vertical vertical displacementdisplacement

SedimentSediment

The demo illustrates:The demo illustrates:The demo illustrates:The demo illustrates: A simplified model of normal faults and

landform before uplift Reaction of landform to gradual vertical

displacement along the parallel normal faults Erosion and deposition as a result of vertical

movements (red is erosion - blue is deposition)

Emergent behaviour of rivers leading to development of braided streams

tectonics

Research challengesResearch challenges

Data structures and modeling– no finite difference models on the curved

surface of the planet– finite element models based on triangles?– object-based models

Describing models– metadata– libraries of models

Research challenges (2)Research challenges (2)

Software environments– PCRaster

Calibration, verification, accuracy Integration across domains

– coupling models– distinct ontologies

Summary: four perspectivesSummary: four perspectives

An immersive environment A metaphor for information organization A distributed database transparent to

the user A representation of the planet's

dynamics

Augmented realityAugmented reality

Information tied to location– accessible by a person at that location– locationally enabled devices

palmtop with GPS cellphone

Delivering DE services in the field– wireless devices– g-commerce

Digital Earth: a mirror worldDigital Earth: a mirror world

Models of the Earth– maps– descriptive text– process models

Collectively, a storehouse of knowledge about the planet– distributed– digital– captures our understanding of the world