8 Architecture of Geographic Information Systems · •Environmental information system Spatial...

8.1 GIS Hardware and Software

8.2 Hybrid vs. Integrated Systems

8.3 Clients and Servers

8.4 Web-based Spatial

Databases

8.5 Summary

Spatial Databases and GIS – Karl Neumann, Sarah Tauscher– Ifis – TU Braunschweig 624

8 Architecture of Geographic Information Systems

[SX08]

• A geographic information system is a system designed to collect, manage, analyze, display spatial data

• Specialized information system that consists of

– Spatial database,

– Spatial database system,

– Application Software

• Often end users only seespecially programmeduser interface


8 Architecture of GIS

http://www.physicalgeography.net/

• Environmental information system



[SX08]

• Tourist information system



[SX08]

• Urban planning information system



[SX08]

• Network information system



http://www.uni-potsdam.de/Geographie/

• GIS hardware mainly differs from "normal"

information systems in the input devices




• Input device: digitizer

– Collection of coordinates

– Magnifying glass with crosshairs

– Electronic pen

– Electromagnetic

surface

– Digitization of maps




• Input device: drum scanner

– Oldest type of scanner

– Provides accurate results

– Usually with very high

resolution

– Original on a rotating drum

– Scanning device always in the

same position to the original



http://www.at-mix.de/

http://www.litho-erfurt.de

• GIS-Software

– Components (user-oriented view)




• Classification of GIS software

– Expert GIS standard GIS, spatial data server, geodatabase

– Desktop-GIS data management for collection and information

– Mobile GIS information, collection, updating

– Web-GIS information, usually no collecting and updating

– Component GIS embedding GIS functionality into third party systems

– GIS-Viewer software for displaying and querying GIS data formats



http://www.esri.com/

• Architecture of GIS can be roughly classified

– File based

– Hybrid

– Layer-oriented

– Integrated



• File based architecture

– First generation of GIS (since approx. 1960)

– All information stored in files

– No logical data independence

– No physical data independence

– No standardization



• Hybrid architecture

– Relational databases are used for thematic attributes

– Spatial data is storedin specific data structureson files

– Consistency of the data is difficult toensure

– Queries whichcombine thematic and spatial attributes arenot possible



• For example, a query which is not possible with

hybrid architecture (see section 4.5)

• Attention: sometimes the term "hybrid GIS"

also is used for such systems, able to integrate

vector and raster data



SELECT b1.idFROM Building bWHERE b

SELECT b1.idFROM Building b1, Building b2WHERE b1.typeOfUse = ’church’

ANDb2.typeOfUse = ’car park’ANDDistance(Centroid(b1.groundPlan),

Centroid(b2.groundPlan)) < 2000;

• Layer-oriented architecture

– Thematic attributes and spatial data

are stored in one single (relational)

database

– Spatial data are modeled as relations

– Introduction of a layer with

geometric functions

– Inefficient access to individual spatial

objects (have to be collected by

means of joins)



• Example of relational modeling of polygons as a

list of points (see section 4.3)

– Id attribute, list position and integer attributes x, y

– For each polygon the values of

position have to start with value 1

and have to be dense

(implementation of a list)



CREATE TABLE Polygons (CREATE TABLE Polygons (id CHAR(20),position INTEGER,x INTEGER,y INTEGER,PRIMARY KEY (id,position));

• Integrated architecture

– Thematic attributes and spatial data are stored in one

single (geographic) database

– Database functions and GIS

functionality in one system

– Database functions support the

processing of spatial data

– Spatial index structures

– Logical data independence

– Standardization possible



• Example of a query which is possible with

integrated architecture;

typically, this query is

evaluated by using an

R-tree index (see section

4.6 and section 5)



SELECT p.idFROM Parcel p,

WHERE intersects (

SELECT p.idFROM Parcel p,

Brook bWHERE intersects (p.groundPlan,

b.geometry);

• Relational join algorithms aren’t applicable for spatial joins (except Nested Loop)

– Sort-Merge-Join

– No order on spatial (multi-dimensional) data


8.2 Spatial Join

matNr result

1005 4.0

1005 1.3

2832 5.0

5119 1.7

8676 1.3

9876 3.7

matNr firstName

1005 Clark

2832 Lois

4512 Lex

5119 Charles

6676 Erik

8024 Jean

– Hashjoin

– A hash function, which assigns the same value to

extended, overlapping objects is not known


8.2 Spatial Join

00

11

22

33

44

55

66

77

00

11

22

33

44

55

66

77

matNr firstName

1005 Clark

2832 Lois

4512 Lex

5119 Charles

6676 Erik

8024 Jean

matNr result

9876 3.7

2832 5.0

1005 4.0

1005 1.3

6676 1.3

5119 1.7

• Spatial join using r-trees

– Suppose the height of both r-trees is the same

– Only MURs on the same level have to be checked for

intersections and only if their parent’s MURs intersect

– A priority queue is used to store the node pairs which

have to be checked

– Filter step of the spatial query evaluation

→ results have to be validated using the original

geometry of the objects


8.2 Spatial Join


8.2 Spatial Join

procedure INDEX_TRAVERSAL_SPATIAL_JOIN(rootA, rootB)begin

priorityQueue ← CREATE_PRIORITY_QUEUE();priorityQueue.ADD_PAIR(rootA, rootB);while NOT priorityQueue.EMPTY() do

nodePair ← priorityQueue.POP();rectanglePairs ← FIND_INTERSECTING_PAIRS(nodePair);foreach p Є rectanglePairs do

if p is a pair of leaves thenREPORT_INTERSECTIONS(p);

elsepriorityQueue.ADD_PAIR(p);

endif;enddo;

enddo;end; http://doi.acm.org/10.1145/1206049.1206056

• ADD-PAIR

– Defines the order in which the priority queue is

processed

• Breadth first search

• Breadth first search with additional ordering of the nodes

on one level i.e. x-coordinate or z-address of the MUR’s

center

• Depth first search


8.2 Spatial Join

1

2

7

3 4

65 9 108

1

2

6

5 8

43 9 107

• Example


8.2 Spatial Join

1

23

4

5

7

6

8

9

a

b

c

fg h

d

e

i

k

j

l

• R-tree of the rivers


8.2 Spatial Join

a

bc

fg h

d

e

i

k

j

l

• R-tree of the rivers


8.2 Spatial Join

II IIII

AA BB CC DD EE

aa cc

bb dd ee

hh ii

jj kk ll

ff gg

a

bc

fg h

d

e

i

k

j

l

AB

C

D E

I

II

• R-tree of the woods


8.2 Spatial Join

1

23

4

5

7

6

8

9

• R-tree of the woods


8.2 Spatial Join

1

23

4

5

7

6

8

9

F

G

H

I

III

IV

IIIIII IVIV

FF GG HH II

11 22

33 44

55 66 77

88 99

• 1. iteration

– nodePair: (rootA, rootB)

– priorityQueue: ((II,III) (I,IV) (I,III))


8.2 Spatial Join

III

IV

I

II

((E,H) (D,H) (I,IV) (I,II))

• 2. iteration

– nodePair: (II, III)

– priorityQueue:


8.2 Spatial Join

D

E

F

G

H

((i,7) (h,7) (D,H) (I,IV) (I,II))

• 3. iteration

– nodePair: (E,H)

– priorityQueue:


8.2 Spatial Join

h

i

5

7

6


8.2 Spatial Join

II IIII

CC AA BB DD EE

aa cc bb dd ee hh iijj kk ll ff gg

IIIIII IVIV

HH GG FF II

11 2233 4455 66 77 88 99

• FIND_INTERSECTING_PAIRS


8.2 Spatial Join

procedure PLANE_SWEEP(listA, listB)begin

statusA ← CREATE_STATUS()statusB ← CREATE_STATUS()while NOT listA.END() OR NOT listB.END() do

if listA.FIRST() < listB.FIRST() thenstatusA.INSERT(listA.FIRST())statusB.REMOVE_INACTIVE(listA.FIRST())statusB.SEARCH(listA.FIRST())listA.NEXT()

elsestatusB.INSERT(listB.FIRST())statusA.REMOVE_INACTIVE(listB.FIRST())statusA.SEARCH(listB.FIRST())listB.NEXT()

endifenddo

end

f g

5

7

6

statusA:

statusB:

Result:

• Cooperating components– Client initiates the communication

– Client sends requests to the server

– Server provides a fixed set of services

– Roles and functions are asymmetric

– Sequence of interaction steps is determined

– Client may accessmultiple servers

– Server may servemultiple clients

– Server may also beclient when processing a request



[Da96]

• Various kinds of realising client/server systems

• The differences arise as a result of the partitioning of total functionality

• Possible sub-functions

– Presentationfunction

– Applicationfunction

– Datamanagementfunction



http://www.it-infothek.de/

• Typical functions of a GIS server

– Selection of thematic and spatial

information from geographic

data base

– Preview of selected spatial data

– Conversion of selected spatial

data into the appropriate target

format

– Cartographic representation of

selected spatial data


8.3 Servers

http://www.dottedeyes.com/

• Selection of some common GIS Server

– ESRI

• ArcGIS

• ArcIMS

• ArcSDE

– GRASS

– Smallworld

– Oracle Spatial

– Postgres, PostGIS


8.3 Servers

• ESRI

– Market leader, founded in 1969 as "Environmental Systems Research Institute"

– Chargeable, not open source, Windows and Linux

– Covers the whole range of GIS functionalities

– Products

• ArcGIS - desktop GIS, includes ArcView, ArcEditor, ArcInfo

• ArcView - basic GIS functionality

• ArcEditor - interactive changes

• ArcInfo - full analytical capabilities

• ArcIMS - internet mapserver

• ArcSDE - spatial database engine


8.3 Servers

• ArcGIS– Complete desktop GIS

• Managing spatial data and metadata

• Editing spatial objects

• Visualizing spatial data

• Selecting spatial objects

• Analyzing of geometric and topological properties

• Import and export of spatial data

• Transformation between coordinate systems

– Interactive interface or callable functions via script language (Python, Perl)

– Based on an object relational database system (meanwhile)


8.3 Servers

• ArcIMS

– Internet mapserver

– Server application for producing and publishing (interactive) maps on the internet (web mapping)

– Created maps can be visualized by a web browser

– Internal use of XML for communication


8.3 Servers

http://www.esri.com/

• ArcSDE

– Server application for the management of spatial data

– Middleware as a layer between

the ArcGIS system and a

database system

(e.g. Oracle, DB2)

– All functions of a database

system (e.g. ACID transactions)

– Spatial access structures

(Grid File)


8.3 Servers

http://www.gisfusion.com/

• GRASS– “Geographic Resources Analysis Support System”

– Free of charge, open source, Linux, Mac OS, Windows

– Offers a variety of GIS functions

• Spatial analysis

• Integrated simulation models

• Geostatistics

• Several projections with transformations

• Map production

• Database connection (Postgres, MySql, Oracle)


8.3 Servers

– Functions are encapsulated in individual modules

• Approx. 10 modules just

for handling vector

geometry, e.g. for adding

or deleting individual

points in polylines

– Grass consists of more than 400 programs and tools

– Grown system

– Somewhat uncomfortable to use


8.3 Servers

http://linuxgazette.net/

• Smallworld

– Product of General Electric (now)

– Market leader in the area of network information systems

– Chargeable, not open source, Windows and Linux

– Professional system for companies and authorities

– Focus on user interface, easy in training, scalability

– Various specialized application modules available from third party developers

• Pipeline

• ALKIS, zoning map, land development plan

• Environmental atlas

• District heating, supply line network

• Electricity, gas, water


8.3 Servers

• Oracle Spatial

– Spatial extension of the Oracle database system(see sections 4.5, 7.3)

– Chargeable, not open source, Windows, MacOS, Linux

– Set of functions for handling spatial data

• Insert, update, delete, select

• Spatial accessstructures

– Specific geometricdata typeSDO_GEOMETRY


8.3 Servers

• MapViewer

– Additional

component

for rendering

spatial data


8.3 Servers

http://www.oracle.com/

• Postgres

– Relational database system with spatial data types and corresponding SQL extensions (see sections 4.5, 7.2)

– Free, open source, Linux, MacOS, Windows

– Following data types are offered

• point (float, float)

• box (point, point)

• lseg (point, point)

• line (point1, point2, ..., pointn)

• polygon (point1, point2, ..., pointn)

• circle (point, float)

– Numerous geometric predicates and functions


8.3 Servers

• PostGIS is an extension of Postgres (Postgres is designed to be extensible)

– Additional data types: MultiPoint, MultiLinestring, MultiPolygon, GeometryCollection

– Syntactic embedding of the new data types is different because they are realized as user-defined types

– First a table is defined

CREATE TABLE ...

then a column with a new data typeis added

SELECT AddGeometryColumn (...)


8.3 Servers

• OpenJUMP is a “unified mapping platform” fitting

to PostGIS

– Editor

– SVG export

– Layer

concept


8.3 Servers

http://jump-project.org/

• Typical functions of a GIS client

– Data acquisition, digitization

– Transformations

– Functions for image processing

– Basic CAD functions

– Constructing of spatial objects

– Data reduction, smoothing, generalization

– User interface

– Presentation of data

– Data output


8.3 Clients

http://www.ikg.uni-hannover.de/

http://www.dgfk.net/

• 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 MapServices are realised– OGC WMS Viewer company:

Intergraph

– mapClient company: con terra

– ArcExplorer WebESRI


8.3 Clients

http://www.cardogis.com/

• Intergraph OGC WMS Viewer

– “Thin Client”, web application

– Can connect to web servers which provide the OGC Web Map Services

– Loads maps and displays them

– Can combine different maps

– Contains configurableGUI

– Requires local database server to store and loaded maps


8.3 Clients

http://www.demis.nl/

• con terra mapClient– Configurable web

application

– Display, navigation,selection, managementof• OGC WMS and WFS

services

• ArcIMS and ArcGISservices

– Measurement of distances and areas

– Drawing of points, lines, and surfaces

– Can be upgraded with further components to a GIS server


8.3 Clients

http://www.conterra.de/de/

• ESRI ArcExplorer Web

– Browser-based mapping application

– Can access ArcIMS services and OGC WMS Web Map Service

– Combination of

different maps

or layers

– Search for locations

worldwide

– Address search (U.S.)

– Works without any

plug-in or applet


8.3 Clients

http://www.esri-germany.de/

• Collection of spatial data is particularly expensive

• Spatial data is durable

• Geoservices are increasingly offered by the internet

• Typical keyword: "Internet GIS"

– Internet GIS applications reachmany users

– Requirement for internet clientsare low

– Standards enable simpleexchanges


8.4 Web-based Spatial Databases

• Application areas of internet-GIS

– Simple information systems

• Standard internet environment with usual plug-ins

• Presentation of interactive maps

• E.g. in the local area for publication of information to

citizens and

visitors



http://www.braunschweig.de/

– Specialized georeferenced information systems

• Additional services to the public or for a restricted group of

people

• Dynamical systems needed, since data is processed during

request

• E.g. address search,

route planner



http://maps.google.de/

– Web-based GIS clients with access to key resources

• Offer advanced functionalities

• Analysis and intersection of spatial data

• Export and update of attributes

• Used mostly in spatial data infrastructures, because user

training is required

– Portals for spatial data

• For providing and selling of large

quantities of data

• Usually data is supplied by different

spatial data servers



http://cdl.niedersachsen.de/

• Internet GIS components



[KZe07]

• Technical options for internet GIS



setting server client remark

statical

websites

HTML documents, graphic

objects

web browser proven feasible and easy

solution

interactive

websites

HTML documents, graphics

objects, extensive embedded

functionalities

web browser with

script support

needed for larger amounts of

and changing selections of data

client

application

HTML documents with

embedded software components,

data files

web browser with

plug-ins such as SVG,

Java, special viewer

with high demands on

presentation, scalability, and

interaction

dynamic

websites

dynamic server application, direct

access to spatial data

web browser independence from the client,

large amounts of data, and a

variety of functions

spatial data

infrastructure

data services which provide

spatial data via pre-defined

interfaces

spatial client, for

example, viewer, web

portal, desktop GIS

access to distributed spatial

databases

terminal

server

high performance server with

terminal suite, GIS software, and

spatial data

special client full access to a desktop GIS via

internet

• OpenStreetMap (OSM) is a free editable

map of the whole world

• Founder: Steve Coast

• Established: August 9, 2004

• Funding: Entirely by donations

• Licensing model: Creative Commons Attribution-

ShareAlike 2.0

• Mission: To map the world and give the data away

for free


8.4 Open Street Map


8.4 Open Street Map

www.openstreetmap.org

• Provide an Open Platform

– OSM Users may freely input and extract data

• Raw sources for OSM Basemap

– GPS track logs

– Existing Free Data Sources (e.g. TIGER/LINE)

– Historical Maps – Out of Copyright mapping

• Users Create Basemap from Raw Sources

– Via Online and Offline Editing Software


8.4 Open Street Map

• OSM's data is made up from the following elements:

– Nodes: The dots that are used to mark specific locations

(such as a post box) or for drawing segments between.

– Ways: An ordered list of nodes, displayed as connected by

line segments. They are used to describe roads, paths etc.

– Closed Ways: Closed ways are ways which go in a

complete loop. They are used to describe areas like parks,

lakes or islands

– Relations: Basically groups of objects in which each object

may take on a specific role


8.4 Open Street Map

• Tags

– Key=value pairs

– Can be assigned to OSM-elements i.e. nodes, ways and

relations

– No content restrictions, but they have to be verifiable

– Recommended set of features and corresponding tags

• in order to create, interpret and display a common basemap

• Not every recommended feature will be rendered

• Some rendered Features are not listed

– Possibility to propose new features/icons


8.4 Open Street Map


8.4 Open Street Map

Key Value Element Comment Rendering Photo

highway motorway A restricted access major divided highway, normally with 2 or more running lanes plus emergency hard shoulder. Equivalent to the Freeway, Autobahn, etc..

highway trunk_link The link roads (sliproads/ramps) leading to/from a trunk road from/to a trunk road or lower class highway.

highway pedestrian For roads used mainly/exclusively for pedestrians/shopping areas. Also for tagging squares and plazas (in which case, add area=yes.

highway steps For flights of steps (stairs) on footways. Use with step_count=* to indicate the number of steps

http://wiki.openstreetmap.org/wiki/Map_Features


8.4 Open Street Map

Key Value Element Comment Rendering Photo

amenity university A University campus or buildings

amenity grit_bin A container that hold grit or a mixture from salt and grit.

landuse vineyard A piece of land where grapes are grown.

access yes/ designated/ official/ private/ permissive/ destina-tion/ delivery/ agricultural/ forestry/ unknown/ no

General access permission. - permissive means there is no legally-enshrined right of access, but the landowner has allowed it at his/her discretion - private ….

http://wiki.openstreetmap.org/wiki/Map_Features

• GPS-Traces


8.4 Open Street Map

File name:GPSDATA_20100113.gpx (download)

Upload:Wednesday, 13. Januar 2010, 11:45 Uhr

Points: 3,162

Coordinate ofstarting point:

-37.8654; 144.695(Map /edit)

owner: Pegaxs

Description: Bike ride

Tags: none

Visibility:Identifiable (list ofordered points with time stamp)

http://www.openstreetmap.org/user/Pegaxs


8.4 Open Street Map

• Database Schema

– 16 administrative tables

– 3 GPX tables

– 2 changesets tables

– 17 geodata tables

• 8 master tables, containing all previous edit history

• 8 current tables, latest revision, used for drawing the map

• 1 table for storing mbrs of countries


8.4 Open Street Map

• OpenStreetMap stats report (13.01.2010)


8.4 Open Street Map

users GPS points nodes ways relations users editing gpx files/nodes

day week month

203726 1357120640 530020786 39265159 327997 206/1350 1096/4613 2912/9768

http://wiki.openstreetmap.org/wiki/Stats

05.200609.2006

• Isle of Wight


8.4 Open Street Map

01.2010

• Export


8.4 Open Street Map

…

…

• GIS to collect, manage, analyze, display spatial data

– Specialized information system

– Spatial database, spatial database system

– Application software

• GIS hardware and software

– Special input devices

– Digitizer

– Drum scanner

– Classification of GIS software


8.5 Summary

• Hybrid vs. integrated systems

– File based architecture

– Hybrid architecture

– Layer-oriented architecture

– Integrated architecture

– Detour [spatial join with R-tree index]

• Clients and Servers

– Various kinds of realising client/server systems

– Typical functions of a GIS server/client


8.5 Summary

• Servers

– ESRI; ArcGIS, ArcIMS, ArcSDE

– GRASS

– Smallworld

– Oracle Spatial

– Postgres, PostGIS

• Clients

– Intergraph OGC WMS Viewer

– con terra mapClient

– ESRI ArcExplorer Web


8.5 Summary

• Web-based spatial databases

– Internet GIS

– Application areas of internet GIS

– Internet GIS components

– Detour [Open Street Map]


8.5 Summary


8.5 Summary

GIS

internetGIS

software

hardware

client/server

systemarchitectures

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