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