Spatial Databases and
Geographic Information Systems
Systems
Karl Neumann
Sarah Tauscher
1.1 Organizational Issues 1.2 Content and Overview 1.3 Literature
1 Introduction
• Lecture
– 23. 10.2009 - 05.02.2010 – 9:45 - 12:00
– Exercises and detours integrated into lecture
1.1 Organizational Issues
Exercises and detours integrated into lecture – URL:
www.ifis.cs.tu-bs.de/
teaching/ws-0910/gis
• Exams
– Oral exam
– 08. - 12. 02.2010
– Register at examination office
1.1 Organizational Issues
Register at examination office
– Get an appointment at the Ifis secretariat
→ Regine Dalkiran
• 2 Spatial Data Modelling
– 2.1 Geometry
– 2.2 Conversion between Vector and Raster Models – 2.3 Topology
1.2 Content and Overview
2.3 Topology – 2.4 Fields
– 2.5 AAA-Project
– 2.6 Operations
– Spatial object/Geoobject: element to model real world data in geographic information system
– Are described by spatial data (geodata)
– Spatial information: custom-designed spatial data – Chief difference to “conventional” objects
1.2 Content and Overview
– Chief difference to “conventional” objects (“What’s so special about spatial?”):
• Geometry
• Topology
– Vector: minimum distance between a point and a line
1.2 Content and Overview
http://worboys.duckham.org/
– Raster: Distance matrices for distance determination
• 3 Mapping of Spatial Data
– 3.1 Properties of Maps
– 3.2 Signatures, Text, Color
– 3.3 Geometric Generalization
1.2 Content and Overview
3.3 Geometric Generalization – 3.4 Label and Symbol
Placement
– 3.5 Summary
– Challenges
• Projection of the 3D surface on two dimensions (paper, film, screen)
• Selection of the spatial objects and their attributes to be displayed
1.2 Content and Overview
their attributes to be displayed
• Generalization of geometric and
thematic properties (simplify, omit depending on scale)
• Exaggeration and displacement
– Douglas/Peucker algorithm
1. given: polyline L, threshold g
2. determine line between the start and end point of L,
3. determine the point of L that is furthest
1.2 Content and Overview
3. determine the point of L that is furthest from the line segment
4. if distance > g then the point is
significant, repeat procedure for both sub-lines,
otherwise remove all the points between
the start and end point of L
http://en.wiki.mcneel.com/• 4 Spatial Queries
– 4.1 Development of SQL – 4.2 Core SQL Queries
– 4.3 Spatial Queries and Core SQL
1.2 Content and Overview
4.3 Spatial Queries and Core SQL – 4.4 Spatial Extension of the
Relational Algebra
– 4.5 Spatial Extensions of SQL
– Query 6:
Ids of churches which are located no more than 2 km from a car park
Building(id: string, typeOfUse: String, groundPlan: Polygon)
1.2 Content and Overview
F
id1( σ
Distance(Centroid(groundPlan1),
Centroid(groundPlan2))<2000
( σ
typeOfUse1=′church′∧typeOfUse2=′car park′
(Building × Building)))
– Therefore evaluation of spatial queries in 2 steps
• Filter step
– Determination of possible hits by evaluation on spatial approximation (lower costs)
• Refinement step
1.2 Content and Overview
• Refinement step
– Evaluation on accurate geometry only for objects of the filter step
• 5 Spatial Access Methods
– 5.1 Quadtree – 5.2 R-tree
– 5.3 K-d tree
1.2 Content and Overview
13
26 11 3
27
29 17
5
4 7
A
B
E G
J
5.3 K-d tree
K– 5.4 BSP tree – 5.5 Grid file – 5.6 Summary
15 23
13 28
24 8 28
17 9
31
29 18
21 22
A
C D
H G
I
– Problems
• Only suitable for points
• False positives, the solutions supplied by the index have to be verified
• Adequacy depends on the position of the query window
1.2 Content and Overview
• Adequacy depends on the position of the query window
– Split at a data points or at an arbitrary points
– Choice of split dimension
• Alternating or dimension with the largest extent
– Choice of split position
• Median or average
1.2 Content and Overview
• Median or average
1 2
2
3
3 21
2 3
3
12 3 4 6 5
1 2
4 3 2
3
• 6 Spatial Data and XML
– 6.1 Standards – 6.2 XML
– 6.3 GML
1.2 Content and Overview
6.3 GML – 6.4 XSLT – 6.5 SVG
– 6.6 Summary
– Example: a DTD of a city
1.2 Content and Overview
<!ELEMENT city(name, inhabitants?, area)>
<!ELEMENT city(name, inhabitants?, area)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT inhabitants(#PCDATA)>
<!ELEMENT area(polygon+)>
<!ELEMENT polygon (point, point, point, point, point*)>
<!ELEMENT point(x, y)>
<!ELEMENT x (#PCDATA)>
<!ELEMENT y (#PCDATA)>
– Path instruction for complex shapes, lines and areas
• Element’s attributes include the attribute “d” for specifying the points of the path
• Attribute “d” contains further commands for the interpretation of the points
1.2 Content and Overview
interpretation of the points
• E.g. a point may be the begin or the end of a curve or of a line
<path id="SN4100_einzelsignaturNadelholz"
• 7 Application Programming
– 7.1 Connecting SQL with Programming Languages – 7.2 Postgres and JDBC
– 7.3 Oracle Spatial and JDBC
1.2 Content and Overview
7.3 Oracle Spatial and JDBC – 7.4 Processing of GML-
based Data
– 7.5 Functional Programming with Polygons
– 7.6 Summary
– For processing geometric attributes the special Java class "JGeometry" is offered
– JGeometry maps the SDO_GEOMETRY data type to a structure (STRUCT)
– Numerous basic methods for accessing spatial
1.2 Content and Overview
– Numerous basic methods for accessing spatial information are offered, including
• createCircle, createPoint, createLinearPolygon, equals, getDimensions, getElemInfo, getFirstPoint, getJavaPoint,
– Perimeter of polygons
1.2 Content and Overview
(define perimeter (lambda (poly) (if (not (null? (trunc-poly poly)))
(+ (point-distance (point1 poly)
(point2 poly)) (perimeter (trunc-poly poly)))(point2 poly)) (perimeter (trunc-poly poly))) 0)))
• 8 Architecture of Geographic Information Systems
– 8.1 GIS Hardware and Software
– 8.2 Hybrid vs. Integrated
1.2 Content and Overview
– 8.2 Hybrid vs. Integrated Systems
– 8.3 Client/Server Systems
– Architecture of GIS can be roughly classified
• File based
• Hybrid
• Layer-oriented
• Integrated
1.2 Content and Overview
• Integrated
– GetCapabilities
• Describes which WFS services are available
• Gives the names of the available feature types
– DescribeFeatureType
• Describes the schema of a feature type
1.2 Content and Overview
• Describes the schema of a feature type
– GetFeature
• Delivers an instance of a feature
<wfs:Query
typeName="AX_Gebaeude">
<ogc:Filter>
<ogc:PropertyIsEqualTo>
<ogc:PropertyName>
• 9 GIS Servers and Clients
– 9.1 Classification Characteristics – 9.2 Servers
– 9.3 Clients
1.2 Content and Overview
9.3 Clients
– 9.4 Summary
– Selection of some common GIS Servers
• ESRI
– ArcGIS – ArcIMS – ArcSDE
1.2 Content and Overview
ArcSDE
• GRASS
• Smallworld
• Oracle Spatial Postgres, PostGIS
– GIS clients are primarily visualisation tools (map viewer, gis viewer)
– Usually they display spatial data or maps via a web browser
– E.g. the OGC Web Map
1.2 Content and Overview
– E.g. the OGC Web Map Services are realised
• OGC WMS Viewer company:
Intergraph
• mapClient company:
con terra
• ArcExplorer Web ESRI
• 10 Remote Sensing
– 10.1 Physical Basics
– 10.2 Recording Techniques – 10.3 Image Processing
1.2 Content and Overview
10.3 Image Processing
– 10.4 Thematic Classification
– 10.5 Summary
– System characteristics
• Recording techniques
– Radiometric resolution – Geometric resolution
• Platform
1.2 Content and Overview
• Platform
– Kind of platform – Altitude
– Orbit – Period
• Mission
– Temporal coverage Spatial coverage
www.atmos.albany.edu/deas/
atmclasses/atm335/history.pdf
www.irs.uni-stuttgart.de
– Example: aerial photo of Braunschweig
• Altitude approximately 1600 m
• Ground resolution 10 cm
• Color reversal film
• Central projection
1.2 Content and Overview
• Central projection
• 21. April 2005
• 11 Location Based Services
– 11.1 Positioning
– 11.2 Car Navigation – 11.3 Map Matching
1.2 Content and Overview
11.3 Map Matching – 11.4 Gazetteer
– 11.5 Privacy
– 11.6 Summary
– Application examples
1.2 Content and Overview
Push Services Pull Services Person-
oriented
Communication A message is pushed to you asking whether you allow a friend to locate you
You request from a friend finder application who is near you
Information You get an alert that a terror You look for the nearest cinema Information You get an alert that a terror
alarm has been issued by the city you are in
You look for the nearest cinema in your area and navigation instructions to get there M-Commerce
and Advertising
A discount voucher is being sent to you from a restaurant in the area you are in
You look for events happening in the area you are in
– Global Positioning System (GPS)
• Enables three dimensional positioning near the earth
• Measuring the runtime of signals between the satellite and the GPS-receiver, from which the distance and the position can be deduced (trilateration)
1.2 Content and Overview
can be deduced (trilateration)
• The transmitted signal describes a circular sphere centered at the satellite on whose surface the signal is received at the same time → circular baseline of equal receiving times
on earth
• 12 Environmental Information Systems
– 12.1 Environmental Data
– 12.2 Collection of Environmental Data – 12.3 Monitoring Networks
1.2 Content and Overview
12.3 Monitoring Networks – 12.4 Laboratory Data
– 12.5 Example: EIS
Baden-Württemberg
– Applications
• Environmental documentation
• Recording, monitoring
• Biotope cadastre
• Radiation detection
1.2 Content and Overview
• Radiation detection
• Simulation of environmental processes
• Environmental compatibility assessment
• Informing the public
http://www.e-c-o.at
– Example: sensor network on Great Duck Island
• For monitoring of the petrels' breeding in the U.S. state of Maine
• Network of 32 sensor nodes
• 9 nodes in different breeding
1.2 Content and Overview
• 9 nodes in different breeding caves
• Temperature measurement in the nest (presence of the old birds)
