Describing change using geographical objects

Gilberto CamaraINPE – National Institute for Space Research

GEOBIA 2012, Rio de Janeiro

source: IGBP

How is the Earth’s environment changing, and what are the consequences for human civilization?

The fundamental question of our time

Global Change

Where are changes taking place? How much change is happening? Who is being impacted by the change?

Geoinformatics enables crucial links between nature and society

Nature: Physical equations Describe processes

Society: Decisions on how to Use Earth´s resources

Earth observation satellites and geosensor webs provide key information about global

change…

…but that information needs to be modelled and extracted

When did the Aral Sea reach the tipping point?

Communicating change is hard

Describing events and processes is very hard

When did the flood occur?

What types of change can be described using geo-objects? What is the role of GEOBIA in describing change?

Landsat Image 13/Ago/2003

Geo-objects in an image

Deforestation 13/Ago/2003 until

07/Mai/2004

Deforestation in 13/Aug/2003 (yellow) +

deforestation from 13/Aug/2003 until 07/mai/2004 (red)

Geo-objects in an image

Deforestation on 21/May/2004

Deforestation in 13/Aug/2003

(yellow) + deforestation from 13/Aug/2003 until 07/May/2004 (red) + deforestation on

21/May/2004 (orange)

Geo-objects in an image

Land change objects

LAND CHANGE OBJECTSBoundaries determined by agreement about land

categories (geometry, topology and properties change)

Images as a source for geo-objects

“Images have an observer-independent ontological status”

G Câmara, M Egenhofer, F Fonseca, A Monteiro. "What´s in An Image?“ COSIT 2001.

What’s in an image?Images = acts of measurement

Segments = mathematical constructs

Ontology-Based Image Analysis

Structur.Ontology

PhysicalOntology

MethodOntology

SemanticMediator

TaskOntology

Applicat.Ontology

Segments (mathematical

constructs)

Objects (conceptualconstructs)

Extracting patterns from sequences of images

M. Silva, G.Câmara, M.I. Escada, R.C.M. Souza, “Remote Sensing Image Mining: Detecting Agents of Land Use Change in Tropical Forest Areas”. International Journal of Remote Sensing, vol 29 (16): 4803 – 4822, 2008.

Linking human actions to land change

Remote sensing image mining

M. Silva, G.Câmara, M.I. Escada, R.C.M. Souza, “Remote Sensing Image Mining: Detecting Agents of Land Use Change in Tropical Forest Areas”. International Journal of Remote Sensing, vol 29 (16): 4803 – 4822, 2008.

Patterns of tropical deforestation

Spatial patterns in the Vale do Anari

irregular, linear, regular

Decision tree for Vale do Anari

Vale do Anari – 1982 -1985

Pereira et al, 2005

Escada, 2003

Patterns/Typology

IRR: Irregular – Colonist parcels

LIN: Linear – roadside parcels

REG: Regular agregation parcels

REG

Vale do Anari – 1985 - 1988

Pereira et al, 2005

Escada, 2003

REG

Vale do Anari – 1988 - 1991

Pereira et al, 2005

Escada, 2003

REG

Vale do Anari – 1991 - 1994

Pereira et al, 2005

Escada, 2003

REG

Vale do Anari – 1994 - 1997

Pereira et al, 2005

Escada, 2003

REG

Vale do Anari – 1997 - 2000

Pereira et al, 2005

Escada, 2003

REG

Vale do Anari – 1985 - 2000

Confirmed by

field work

Pereira et al, 2005

Escada, 2003

REG

Marked land concentrationGovernment plan for settling many colonists in the area has failed. Large farmers have bought the parcels in an illicit way

Land change patterns: Anari (1985-2000)

Discovering the history of land change objects

Reconstructing the history of a landscape using topological information of geo-objects

"Case-Based Reasoning for Eliciting the Evolution of Geospatial Objects". Joice Mota, Gilberto Câmara et al, COSIT 2009.

When was this area converted from food to biofuel production?

Coverage set (remote sensing

images)

Time Series (vegetation

index)

Geographic Data Mining Analyst (GeoDMA)

Visualizing time series in polar coordinates

Objects and events

The coast of Japan is an object

The 2011 Tohoku tsunami was an event

Processes and events

Flying is a process - Virgin flight VX 112 (LAX-IAD) on 26 Apr 2012 is an event

When did the Aral Sea shrank to 10% of its original size?

Aral Sea (an object) – disaster (an event)

objects exist, events occur

Mount Etna is an objectEtna’s 2002 eruption was an event

A view on processes and events

Objects EventsMatter Processes

Space Time

Count

Mass

water or lake? football or game?

(Worboys & Galton)

A pragmatic view on objects and events

Objects EventsMatter Processes

Space TimeObservable

Abstract

water or lake? football or game?

Object (GPS buoy) + event (tsunami)

source: USGS

Events are categories (Frank, Galton)

identity : id · a = a

composition : a, b, c, c = a.b ∀ ∀ ∃

associativity : a · (b · c) = (a · b) · c

Building blocks: Basic Types

type BASE = {Int, Real, String, Boolean}

operations: // lots of them…

Building blocks: Geometry (OGC)

type GEOM = {Point, LineString, Polygon, MultiPoint, MultiLineString, MultiPolygon}

operations: equals, touches, disjoint, crosses, within, overlaps, contains, intersects: GEOM x GEOM → Bool

Building blocks: Time (ISO 19108)

type TIME = {Instant, Period}

operations: equals, before, after, begins, ends, during, contains, overlaps, meets, overlappedBy, metBy, begunBy, endedBy: TIME x TIME → Boolean

type STobj [T: TIME, G: GEOM, B: BASE] operations:

getObs: ST → {Obs}begins, ends: ST → Twhere: ST x T → Gafter, before: ST x T → STduring: ST x Period → ST

value: ST x T → B

What do ST objects have in common?

Moving objects

MOVING OBJECTS Objects whose position and extent change continuously

Land change objects

LAND CHANGE OBJECTSBoundaries determined by agreement about land

categories (geometry, topology and properties change)

How many walruses reached Baffin island?

When did the Aral Sea shrank to 10% of its original size?

areaAral: STObject → TimeareaAral obj:{ area0 = area (obj1.begin());

for t = obj.begin(); t <= obj.end(); t.next()if area (obj1.begin()) < 0.10*area0) return

t;}

The event data type

An event is an individual episode with a beginning and end, which define its character as a whole.

An event does not exist by itself. Its occurrence is defined as a particular condition of one spatiotemporal type.

The event data type

Type Event [T1: TIME, T2: TIME] uses ST

operations: new: {ST x (T1, T2) → Event compose: Event x Event → Eventintersect: Event x Event → Event

Exploração intensiva

Floresta

Perda >90% do dossel

Corte raso

Perda >50% do dossel

time

Event 1

Event composition Forest loss > 20%

Floresta

Loss > 90%

Clear cut

Loss > 50%

Event 2

Event 3

Event 4

Discovering the history of land change objects

Reconstructing the history of a landscape

TerraLib: spatio-temporal database as a basis for innovation

Visualization (TerraView)

Spatio-temporalDatabase (TerraLib)

Modelling (TerraME)

Data Mining(GeoDMA)Statistics (aRT)

Algebras for spatio-temporal data are a powerful way of representing change