Geographical Ontologies: An Overview

Gilberto CamaraNational Institute for Space Research, Brazil

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What’s out there?

Hic sunt leones et dragonesWhat’s out there?

fonte: Carlos Nobre

What’s out there?

Reality

What’s out there?

What’s out there?

Data Data

GIS A GIS B

Format A Format B

Lake Habitat

The realist perspective (John Searle)

1. There is a real world that exists independently of us, our experiences, our thoughts and our language.

2. We have direct perceptual access to that world through our senses and our measurement devices.

3. Words in our language can be used to refer to real objects in the world.

4. Our statements are typically true of false depending on whether they correspond to the facts in the real world.

5. Some features of the world exist independently of us, such as mountains and lakes. Some features of the world are dependent on a socially-constructed agreements, such as boroughs and land parcels.

Humans before language: cave paintings

17,000 BCE, Lascaux, France

It all begins with observations…

What’s out there?

We use words in our language to describe the world

What’s out there?

From analogue spaces to digital spaces

social network

sensors everywhere

mobile devices

ubiquitous imagery

Mobile devices, crowdsourcing, massive Earth observation sets: new technologies, new challenges

Geoinformatics enables crucial links between nature and society

Nature: Physical equations Describe processes

Society: Decisions on how to Use Earth´s resources

EVENTS / POINT SAMPLES

SURFACES / REGULAR GRIDS

AREA DATA / POLYGONS

FLUX DATA / NETWORKS

X,Y,ZX,Y,Z X,Y,Z

X,Y,Z

X,Y,Z

From data to computer representations

1991

iex

Digital spaces: Social exclusion in São Paulo

2000

Digital space: Flows in networks

Digital spaces: Crime mapping in Calgary (CA)

Representation

The Medieval King has in him two Bodies: a Body natural, and a Body politic.

Representations of the King fulfill a key political function

Representation

The King had two bodies:

Otho III, holding a royal orb, inside a mandorla.

Vivet et non vivit

Representation

"Mosaic in the Martorana at Palermo, representing the coronation of King Roger II at the hands of Christ, where the desired effect of making the God manifest in the king was achieved by a striking facial resemblance between Roger and Christ." Ernst H. Kantorowicz, The King's Two Bodies: A Study in Mediaeval Political Theology (Princeton: 1957) 65

Conceptual models: built from abstractions

Spatial Data

Natural Domain

HumanDomain

IMAGES

-planes-satellites

ENVIRONMENTALDATA

-topography-soils-temperature-hidrography-geology

CADASTRALDATA

-parcels-streets-land use

CENSUS DATA

-Demographics-Economics

INFRASTRUCTURE

-roads-utilities-dams

System designer view of spatial data

A geographical ontology

Geographical reality

Natural objects Social objects

boundaries propertiesidentity

Geographical reality

Natural objects Social objects

boundaries

identity

Geo-objectsobservations

attributes Fields

properties

Boundaries: a key concept of social objects

The enclaves of Baale-Hartog

India-Bangladesh enclaves

Dahala Khagrabari: a 3rd order enclave

Büsingen in Germany

What makes a sovereign state?

Republic of Crimea?

It all begins with observations…

What’s out there?

The continuously changing landscape of the Earth (topography)

Mountains with names (Alps, Mont Blanc)

It all begins with observations…

What’s out there?

The continuously changing landscape of the Earth (topography)

Mountains with names (Alps, Mont Blanc)

Fields (coverages) objects

What about objects?

Mont Blanc

Objects are language constructs, built upon observations They require both an external reality and a conscious act to identify their existence

Objects as mental constructions derived from physical reality

Mont Blanc

“Mont Blanc” is a socially-accepted name for a specific topographic featureWhere does “Mont Blanc” start and “Dôme du Goûter” end?

Objects as mental constructions derived from physical reality

Walrus W1

To understand animal behaviour, we tag them and assign them an identity

Objects as mental constructions derived from physical reality

Walrus W1

To understand animal behaviour, we tag them, assign them an identity and track their movements

Objects as mental constructs derived from social reality

“Germany (1914)” is a geographical object whose existence is defined by laws and treaties

Die Proklamation des Deutschen Kaiserreiches 1871

Objects as mental constructs derived from social reality

“Germany (2013)” is a geographical object whose existence is defined by laws and treaties

Einigunsvertrag 1990Two-plus-Four Agreement 1990

Was Germany a nation before it were a state?

Germania, in a 1834 fresco. When did Germany start to exist?

What were the boundaries of Germany when Goethe lived?

The trajectory of German borders

Boundaries of natural and social objects may coincide (but are not the same)

The boundaries of the Republic of Cuba are not the boundaries of the island of Cuba (think of Guantánamo)

Natural objects: we measure properties in reality…

Map showing main topographical features in Europe.

…but always inside a bounding space…

Map showing main topographical features in Europe.

Where is Europe in this map?

Temperature, Water ph, soil acidity...

The natural world has continuous spatial variation

Properties of natural objects can be continuous

Map showing main topographical features in Europe.

For every point inside Europe, there is a height measurement

Soils map of Europe

Soils map of Europe

How real are those boundaries?

Gilberto Camara, Max J. Egenhofer, Karine Ferreira, Pedro Andrade, Gilberto Queiroz, Alber Sanchez, Jim Jones, and Lubia Vinhas

image: INPE

Fields as a Generic Data Typefor Big Spatial Data

How can we best use the information provided by big data sources?

Big data requires new conceptual views

Image source: Geoscience Australia

Everything starts with measurements (Kuhn)

“All information ultimately rests on observations, whose semantics is physically grounded in processes and mathematically well understood. Exploiting this foundation to understand the semantics of information derived from observations would produce more powerful semantic models”.

An example of big geospatial dataimage source: NOAA

ARGO buoys - 3,500 floats 120,000 temp, salinity, depth profiles/year

ARGO buoys: innovative technologySensors measure down to 2,000 m, 10-Day Cycle

Floating buoys measuring properties of the oceans

images source: NOAA

Another example: Free and big Earth Observation data

Image source: NASA

Open access data (US, EC, BR, CH): 5Tb/day

Earth observation satellites provide key information about global change …

… but that information needs to be modeled and extracted

To deal with big geospatial data, we need to reassess the core concepts of Geoinformatics

Premise 1: Reality exists independently of human representations and changes continuously

Premise 2: We have access to the world through our observations

Premise 3: Computer representations of space and time should approximate the continuity of external reality

Temperature, Water ph, soil acidity...

Natural world has continuous spatial variation

Conjecture 1: Data models for space-time data should be as generic as possible

We need to represent volume, variety, velocity

Conjecture 2: Space-time data models need observations as their building blocks

An observation is a measure of a property in space-time

Conjecture 3. Sensors only provide samples of the external reality

To represent the continuity of world, we need more!

Willis Eschenbach

temp = (2 + sin(2 π* (julianday + lag)/365.25)) ˆ1.4

Willis Eschenbach

Conjecture 4: Approximating external reality needs space-time data samples and estimators

Conjecture 5: Fields = Sensor data + Estimators

A field estimates values of a property for all positions inside its extent

(fields simulate the continuity of external reality)

Fields as a Generic Data Type

estimate: Position Value

Positions at which estimations are madeValues that are estimated for each position

Fields as a Generic Data Type

estimate: Position Value

Positions are generic locations is space-timeValues are generic estimates for each position

Fields as a Generic Data Type

estimate: Position Value

Instances of Position: space, time, and space-time Instances of Value: numbers, strings, space-time

An Australian Geoscience Data Cube

A time series field (tsunami buoy)

positions: time values: wave heightimage: Buoy near the coast of Japan

An Australian Geoscience Data Cube

A coverage field (remote sensing image)

image: USGS

positions: 2Dspace values: soil reflectance

An Australian Geoscience Data Cube

coverage setimages: USGS

A field of fields

positions: time values: coverages (2DSpace number)

A trajectory field

positions: time values: space

8/8/99

11/7/03

Japan/East Sea

Russia

Japan

Argo float UW 230deployed 02.08.199910-day interval data until 07.11.2003

source: Stephen RiserUniversity of Washington

A field of fields (Argo floats in Southern Ocean)

Positions: space Values: trajectories (time space)

External Reality

External Reality

Observ.Observ. FieldsFields

ObjectsObjects

EventsEvents

Conjecture 6: To identify objects and events in our descriptions of reality, we need first to define fields

Geographical reality

Natural objects Social objects

boundaries

identity

Geo-objectsobservations

attributes Fields

properties

Conclusion 1: The Fields data type is a generic model for

different kinds of big space-time data

image: INPE

Conclusion 2: The Fields data type enables a better description of

of big space-time data than the layer view

image: INPE

Conclusion 3:The Fields data type may foster a new generation

of GISs that deal with big space-time data

image: INPE