Spatial Information

8/2/2019 Spatial Information

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Spatial Information

Spatial information is information in 2, 3 or 4 dimensions. It is information wherelocation has some importance or benefit and is not necessarily about locations on

the surface of the Earth (e.g., can be a body organ or system).

"Spatial" has to do with any multi-dimensional frame, e.g.,:

Medical images are referenced to the human body;

Engineering drawings are referenced to a mechanical object;

Architectural drawings are referenced to a building.

A location can be a body organ or system. Screenshot of BodyViewer, an

ArcView extension developed by GeoHealth, Inc. BodyViewer allows users

to map any database that contains a geographic reference (e.g., postalcodes, street addresses, census tract numbers) and an ICD-9 or ICD-10

code (diagnoses).

Geographic information is a subset of spatial information, though the terms are

often used interchangeably. "Geographic" is concerned with planet Earth: its two-dimensional surface, its three-dimensional atmosphere, oceans, and sub-surface.

(Bryan, 2000)


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Estimates are that 80% of all data has a spatial component. This data can bequeried and analysed to answer questions such as "How many (e.g., healthcare

facilities, patients with a specific profile, etc.)?" "What kind/type (e.g., type ofhealthcare facility: GP surgery, district hospital, teaching hospital, specialised

centre, etc.)?" "Where are they located (e.g., relationships between populations,

their locations and available/planned healthcare facilities)?" (See also: 'SpatialAnalysis'.)

Geographically referenced data refers to data referenced by location on Earth

(e.g., latitude/longitude, northing/easting) in some standard format.

Geographic References and Geocoding

Geographic information contains either an explicit geographic reference, such asa latitude and longitude or national grid co-ordinate, or an implicit reference such

as an address, postal code, census tract name, forest stand identifier, or road

name. An automated process called geocoding is used to create explicitgeographic references (multiple locations) from implicit references (descriptions

such as addresses). These geographic references allow us to locate features,such as a business or forest stand, and events, such as an earthquake or disease

outbreak, on the earth's surface for analysis.

Geographic information systems rely on two interrelated types of databases:

The Spatial Database

Describes the location and shape of geographic features, and their spatial

relationship to other features. The information contained in the spatial databaseis held in the form of digital co-ordinates, which describe the spatial features.

These can be points (for example, hospitals), lines (for example, roads), orpolygons (for example, administrative districts). Normally, the different sets of

data will be held as separate layers, which can be combined in a number ofdifferent ways for analysis or map production.
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The Attribute Database

The attribute database is of a more conventional type; it contains data describingcharacteristics or qualities of the spatial features (i.e., descriptive information):

land use, type of soil, distance from the regional centre, or, using the same

examples as in the preceding paragraph, number of beds in the hospital, type ofroad, population of the administrative districts. Thus, we could have health

districts (polygons) and health care centres (points) in the spatial database, andcharacteristics of these features in the attribute database, for instance persons

having access to clean water, number of births, number of 1 year old children

fully immunised, number of health personnel, and so on. (Loslier, 1995 in GISfor Health and the Environment)

GIS links spatial data with geographic information about a particular feature on a

map. The information is stored as attributes of the graphically represented

feature.

Example: A line that denotes a road tells you nothing but its location. An attribute table storesall relevant (descriptive) information about this feature, which can be queried and displayed in

many formats based on the users needs.

Points, Lines and Polygons

As mentioned above, GIS attempts to describe all features in geometric terms.


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Point: discrete location represented as a co-ordinate pair (e.g., sampling

locations, disease cases, hospitals, and town centroids).

Line (Arc): set of ordered co-ordinates represented by a string of co-

ordinates (e.g., streams, power and pipelines, and transportation routes).

Polygon (Area): closed feature whose boundary encloses a homogeneous

area represented by a closed string of co-ordinates which encompass an

area (e.g., land use, lakes, census tracts, hospital catchment area, andtown boundaries).

Many features can be described by either a point or a polygon. Similarly, linescan be of a specific width. Map scale and resolution define the conditions for

appropriate application of these feature types. The uses of co-ordinate based

analysis are only limited by the imagination of the user.

Vector and Raster GIS

There are two major methods to input, store and visualise mapped data in GIS.

Geographic Information Systems which store map features in vector format storepoints, lines and polygons with high accuracy. They are preferred in urban


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applications where legal boundaries and the analysis of networks are important.Applications of urban GIS include location and allocation of critical resources such

as hospitals, study of disease outbreak patterns and crime analysis.

Raster Geographic Information Systems, which store map features in raster or

grid format, generalise the location of features to a regular matrix of cells. RasterGIS data structures are preferred for digital elevation modelling (DEM recordsterrain elevations for ground positions at regularly spaced horizontal intervals -

see USA photo below), statistical analysis, remotely sensed data, simulationmodelling, and natural resource applications like sedimentation and water quality

studies.

In raster-based analysis, the areas of analysis are divided into squares of uniform

size (cells). Each cell characterises the feature of interest within this area with asingle value. Digital image data, including aerial photos and satellite imagery, are

stored in raster format (as pixels). GRID cell-based modelling uses the rasterformat to determine routing patterns and terrain.


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An aerial photo

A digital elevation model (DEM) of the USA

Vector data on the other hand, are coordinate-based data structures commonlyused to represent linear features (polygons can be formed by closed strings ofco-ordinates). Each feature in this format is represented as a list of ordered x,y

co-ordinates.

Computer algorithms exist that can convert data of one type to the other.


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Thematic Mapping

Maps in Geographic Information Systems are represented thematically. Astandard topographic map will show roads, rivers, contour elevations, vegetation,

human settlement patterns and other features on a single map sheet. In a GIS

these features are categorised separately and stored in different map themes oroverlays. For example, roads will be stored in a separate overlay. Likewise, rivers

and streams will each be stored as a separate theme. This way of organising datain the GIS makes maps much more flexible to use since these themes can be

combined in any manner that is useful (individual themes can be 'turned on' and'off' as needed).


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Choropleth Maps

These are thematic maps portraying properties of a surface using area symbols

such as shading. Area symbols on a choropleth map usually represent

categorised classes of the mapped phenomenon, e.g., population density.


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Examples of choropleth maps


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Maps Defined

A map is a graphic representation of some part of the earths surface. A mapusually contains a series of themes or coverages that are often combined to form

the final product. A map also contains descriptive information (e.g., legend) to

help readers interpret the details on the map.

Map Scale

The map scale tells the user how the map relates to the real world features it

represents.

Scale: describes the relation between a single map unit to the number of

same units in the real world, e.g., 1:1000 (1 inch on the map = 1000

inches in the real world - see also 'Resolution' below).

Scale Bar: compares the map units to an established real-world unit of

measure, e.g., 1 inch = 2.5 miles. It helps users measure real-worlddistances on the map.

The term map is also used to describe a GIS Project or View. A map can provide

an interpretation of features on the earths surface. Scale, map units and datalayers (themes or coverages) are an inherent part of a GIS and allow users to

conduct spatial queries and measure distances in their projects when needed.

Co-ordinate Systems

In a GIS, locations on the earths surface described by points, lines, and polygons

are defined by a series of x,y co-ordinates. Co-ordinate systems can be self-described or in units that relate to the real world. Decimal degrees; degrees,


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minutes, seconds; metres; and feet are all examples of units of measure in a co-ordinate system.

A degree or is a unit of measurement equal to 1/360 of a circle. A degree oflatitude on the earth's surface is about 69 miles. A degree of longitude is about

69 miles at the equator and undefined at the poles, but any point on the surfacerotates through a degree of longitude in about 4 minutes of time. Minute or ' isthe sixtieth part of a degree of angular measurement, often represented by the

sign ' as in 12 30', read 12 degrees, 30 minutes. Arcsecond or " is the sixtiethpart of a minute of angular measure often represented by the sign ", as in 30",

which is read 30 seconds.

Decimal degrees are the decimal representation of fractions of degrees. Manypaper maps express co-ordinates in degrees, minutes, seconds (e.g., 40 30'),

where minutes and seconds are fractions of degrees. 30 minutes equal half a

degree, and 30 seconds equal half a minute. GIS software, however, expressescoordinates in decimal degrees (e.g., 40.50 degrees), where fractions of degrees

are expressed as decimals. Thus, the longitude: 40 degrees, 30 minutes, wouldbe expressed in ArcView as 40.5 degrees.

Try this:Online Conversions of Degrees, Minutes, Seconds and Decimal Degrees

for Co-ordinates by the Audio Services Division of the Federal CommunicationsCommission, US

x,y co-ordinates define the location of map features. Co-ordinate systems must

be consistent between map layers. For any database to be useful for spatial

analysis, the database must be registered to a recognised global co-ordinatesystem.

A co-ordinate system consists of:

A Spheroid: a mathematical description of the earths shape.

A Map Projection: a mathematical conversion from spherical to planar co-

ordinates.

Map Projections
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The accuracy of measurements, e.g., of distance, done on a map is affected by

the type of map projection used to draw this map.


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Resolution

The accuracy with which a given map scale can depict the location and shape ofmap features is known as resolution. The larger the map scale, the higher the

possible resolution. As map scale decreases, resolution diminishes and feature

boundaries must be smoothed, simplified, or not shown at all. Resolution plays alarge role in GIS, especially in raster-based modelling.

Resolution plays a large part in the ability of a map to accurately describe theearths features. It is essential that the user be mindful of the scale of the data

layers. Serious errors can result if the theme lacks sufficient resolution to

effectively describe an area of interest. A GIS does not tell its user that she hasmade an error in choosing the right data layer for her project.

Topology

Topology is a mathematical procedure for explicitly defining spatial relationships.

Arcs connect to each other at nodes (connectivity),

Arcs that connect to surround an area define a polygon (area definition),and

Arcs have direction and right and left sides (contiguity).


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Connectivity: Arc-Node Topology

Points along the arc that define its shape are called vertices.

Endpoints of arcs are called nodes.

Arcs join only at nodes.

Area Definition: Polygon-Arc Topology


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Polygons are represented as a series of x,y co-ordinates that connect to definean area. The GIS also stores the list of arcs that make up the polygon.

Contiguity


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Every arc has a direction. The GIS maintains a list of polygons on the left andright side of each arc. The computer uses this information to determine which

features are next to one another.

Getting Data into a GIS - Sources of Electronic Data Files

This can be done by:

Digitising hard copy maps (see 'Digitisers' below); Keyboard entry of co-ordinate data (co-ordinates are added as a series of

numbers defining the location of a point, the shape of a line, or the co-ordinates that

define a closed area (polygon); very accurate; requires minimal conversion, but can be

time intensive);

Electronic entry using a data file;

Scanning a map manuscript; and

Converting or reformatting existing data.

The Global Positioning System (GPS) can be also used in creating maps.
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Electronic data files are the easiest way to get data into a GIS.

Ready-to-use data sources include:

DXF: Auto-CAD files/Scanning products;

DLG: Digital Line Graphs available from the USGS (US

Geological Survey URI:

http://www.usgs.gov/pubprod/index.html);

TIGER: 1990+ Census files (US, URI:

http://tiger.census.gov/);

Ordnance Survey Maps: Britain's National Mapping

Agency (URI: http://www.ordsvy.gov.uk);

Bartholomew Mapping Solutions - Free Samples for ArcView and MapInfo(London, Great Britain and Europe)

SHP: ArcView Shape files (many available for download from HealthGeomatics'Resources' page);

Can also add point data using dBase file with x,y co-ordinates in decimaldegrees.

Digitisers
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A digitiser converts spatial features on a hard copy map into digital format. Point,

line and area features are converted into x,y co-ordinates. The process involvesmanually tracing all features of interest using an electronic stylus. Good base

maps must be used. After digitising, a procedure known as transformation

converts digitiser units to a real-world co-ordinate system. Tics are used toprovide the relationship between the two co-ordinate systems.

Product: Coverage

This term is used in a GIS to describe a spatial dataset that has a particular

theme. A coverage consists of topologically linked geographic features. Formaximal analytical power, each theme should exist as a separate coverage;

different feature types can coexist in a coverage if they describe the same data.

Four Main Types of Maps/Data Exist:


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Base Maps: include streets and highways; boundaries for census, postal,and political areas; rivers and lakes; parks and landmarks; place names;

and USGS raster maps.

Business Maps and Data: include data related to census/demography,

consumer products, financial services, healthcare, real estate,

telecommunications, emergency preparedness, crime, advertising, businessestablishments, and transportation.

Environmental Maps and Data: include data related to the environment,weather, environmental risk, satellite imagery, topography, and natural

resources.

General Reference Maps: world and country maps and data that can be

a foundation for a GIS database.

Data Availability and Quality Issues

One potential problem with GIS is the availability and qualityof data needed bysuch systems to use and analyse in order to produce meaningful results. Thedata provided may be inaccurate or incomplete or inappropriate for some

particular use, e.g., not of the appropriate geographic scale needed in somesituation (Albert et al, 2000). Sometimes, due to patient privacy and

confidentiality issues, researchers do not have access topointpatient data and

census tract data (polygon; aggregated data) is all that is available.

Data is usually accompanied by descriptions (metadata). Spatial data quality

standards are now in place to help users understand what is out there and the

intended purpose of the dataset.

==========================================

Spatial Analysis and GIS FunctionsPlease be patient! This page takes about 5 minutes to download over a 56.6K modem (13 seconds over T1), but is worthwaiting for it.

Spatial Analysis in ArcView (executable video adapted from ESRI educationalmaterial)

Spatial analysis involves data queries performed on geo-referenced information

to answer complex questions, like "How many people live within one mile of ahazardous waste site in the United Kingdom?"

From Simple Questions to Analytic Questions

Once we have a functioning GIS containing our geographic information, we can

begin to ask simple questions such as:
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How far is it between two places? (measuring distances)

Where is land zoned for industrial use?

And analytical questions such as:

Where are all the sites suitable for building new houses (or new healthcarefacilities)?

If we build a new highway here, how will traffic be affected?


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Spatial Analysis not just a map. With GIS, users can turn data into information, askquestions and interact with the system

GIS provides both simple point-and-click query capabilities and sophisticatedanalysis tools to provide timely information to managers and analysts alike. GIS

technology really comes into its own when used to analyse geographic data to

look forpatterns and trends and to undertake "what if" scenarios. By applyingthe latest GIS to public health research, it is possible to confirm an existing

hypothesis about the cause of a certain disease, to identify previously unstudied,preventable causes of a disease and to determine people at risk (risk

assessment). Modern GIS have many powerful analytical tools, but two areespecially important:proximity analysis and overlay analysis.

Proximity Analysis

How many houses lie within 100 m of this water main?

What is the total number of patients within 10 km of this healthcare

facility?

What proportion of identified cases lies within 500 m of a suspected well

(as source of infection)?


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To answer such questions, GIS technology uses a process called buffering todetermine the proximity relationship between features.

Overlay Analysis

The integration of different data layers involves a process called overlay. At itssimplest, this could be a visual operation, but analytical operations require one ormore data layers to be joined physically. This overlay, or spatial join, can for

example link land-use and environmental data to population and disease data.

Let's consider this example: we want to assess the risk to people living in acertain area regarding their exposure to some carcinogenic pesticide that had

been sprayed and polluted the soil. We can use GIS to calculate the distance

from the residential parcels to the likely sources of pollution.

But since forests reduce drift from aerial spraying of pesticides by capturing

some of the spray in their foliage, we should also overlay data about land use(e.g., forests, homes, etc.) with data about sources of pollution (e.g., sprayed

areas, cranberry bogs, etc.) to see where forests come between pollution andhomes (protecting homes from pollution). GIS could be then used to identify the


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areas with the greatest risk of exposure by selecting residential land-usepolygons that intersect or are adjacent to pesticide sources.

Data Linkage for Analysis


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Multiple databases can be linked and related

Analysis requires data linkage, within the same dataset and/or in a seconddataset. GIS uses geography, or space, as the common key element between

datasets. Information is linked only if it relates to the same geographic area. GIScan communicate with conventional DBMS.

Spatio-Temporal Analysis

By adding a temporal (time) dimension to spatial data and analysis, we can track

changes that might occur regarding some variable/condition within the same

location with time. Also the variable/condition we are studying might change

locations with time, or extend beyond the original location to involve additionalones.

Spatial Analytic Techniques for Medical Geographers

(Albert and Gesler, 2000)
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See also:

Diggle P. Spatial Statistics for Environmental Epidemiology. Medical

Statistics Unit, Lancaster University, UK. 2000

The GeoMed Advisor: A Disease Clustering Advisor: The advisor will ask you aseries of questions about your data and the kind of clustering you wish to detect, thensuggest an appropriate test (Source: UMICH.EDU, US)

Visualisation

For many types of geographic operation the end result is best visualised as amap or graph. Maps are very efficient at storing and communicating geographic
http://vega.soi.city.ac.uk/~dk708/res/spatial_statistics.pdfhttp://vega.soi.city.ac.uk/~dk708/res/spatial_statistics.pdfhttp://vega.soi.city.ac.uk/~dk708/res/spatial_statistics.pdfhttp://vega.soi.city.ac.uk/~dk708/res/spatial_analysis.exehttp://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://sun2539.sph.umich.edu:2000/geomed/stathelp/advisor.html%27http://vega.soi.city.ac.uk/~dk708/res/spatial_statistics.pdfhttp://vega.soi.city.ac.uk/~dk708/res/spatial_statistics.pdfhttp://vega.soi.city.ac.uk/~dk708/res/spatial_analysis.exehttp://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://sun2539.sph.umich.edu:2000/geomed/stathelp/advisor.html%27


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information. While cartographers have created maps for millennia, GIS providesnew and exciting tools to extend the art and science of cartography. Map displays

can be integrated with reports, three-dimensional views, photographic images,and other output such as multimedia.

GIS combines various display methods, all of them very useful in supporting the decision maker

In the Health Sector, GIS Can Answer the Following Questions andServe the Following Functions:
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Some Real-Life Examples:


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Site location and client distance


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Modelling future trends


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Clusters and comparison of data


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Environmental monitoring and modelling - toxic plume


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Types of GIS

N.B.: The following GIS types are not necessarily mutually exclusive and a

GIS application can be always classified under more than one type.

Four-dimensional GIS

While spatio-temporal geo-representations can handle two dimensions of space

and one of time, four-dimensional GIS are designed for three dimensions ofspace and one of time.

Multimedia/hypermedia GIS

Multimedia/hypermedia GIS allow the user to access a wide range of

georeferenced multimedia data (e.g., simulations, sounds and videos) by

selecting resources from a georeferenced image map base. A map serving as theprimary index to multimedia data in a multimedia geo-representation is termed a

hypermap. Multimedia and virtual geo-representations can be stored either inextended relational databases, object databases or in application-specific data

stores. Raper (2000) mentions several examples including a multimedia atlas

that has been developed for the tourist information system in China.


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Imagine having a real-time (using telecommunication links) multimedia GIS that

can audio-visually monitor different locations at the same time; one applicationof such system could be as a decision support tool to improve the analysis of

traffic problems and the assessment of noise in urban planning andmanagement.

Since video is a spatio-temporal projection of the world in imagery, it can be

considered capable of fully multi-dimensional geo-representation. It can be usedfor mapping from moving platforms, for target positioning, for the measurement

of geo-phenomena such as air pollution, and as a process monitoring system.Video imaging has also become a recognised and valuable new technique of

remote sensing since the 1990s.

Web GIS

Widespread access to the Internet, the ubiquity of browsers and the explosion of

commodified geographic information has made it possible to develop new formsof multimedia geo-representations on the Web. ESRI, for example, provides a

good range ofInternet mapping solutions based on their RouteMAP IMS andArcIMS (Internet Mapping Server) architectures.

Many current geomatics solutions are Web-based overtaking the traditional

Desktop environment and most future one are expected to follow the samedirection.

ESRI promotional video on the use of GIS in crime- and fire-fighting and by

insurance companies and even people looking for a house to buy; the last partof this video, "trying to locate a house to buy", describes www.realtor.com, a

Web GIS (Format: RealVideo; Running Time: 2:42 min. - Source: ESRI, US)
http://vega.soi.city.ac.uk/~dk708/pg3_2.htmhttp://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.esri.com/software/internetmaps/index.html%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.esri.com/software/routemapims/index.html%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.esri.com/software/arcims/index.html%27http://vega.soi.city.ac.uk/~dk708/res/esri_promo2.rmhttp://vega.soi.city.ac.uk/~dk708/res/esri_promo2.rmhttp://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.realtor.com/%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.esri.com%27http://vega.soi.city.ac.uk/~dk708/pg3_2.htmhttp://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.esri.com/software/internetmaps/index.html%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.esri.com/software/routemapims/index.html%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.esri.com/software/arcims/index.html%27http://vega.soi.city.ac.uk/~dk708/res/esri_promo2.rmhttp://vega.soi.city.ac.uk/~dk708/res/esri_promo2.rmhttp://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.realtor.com/%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.esri.com%27


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Related Links:

HealthQuery

The National geographic MapMachine

ATM Locator

Virtual Reality GIS

Virtual Reality GIS have been developed to allow the creation, manipulation andexploration of geo-referenced virtual environments, e.g., using VRML modelling

(Virtual Reality Modelling Language). Virtual Reality GIS can be also Web-based.

Applications include 3D simulation for planning (to experiment with differentscenarios).

Related Links:

An Investigation into User Requirements for Advanced Spatial DecisionSupport Systems (University of Nottingham, UK)

This project (now completed) was funded by the UK Economic and Social Research Council

(ESRC) with the aim to assist users in environmental design tasks, using three key
http://vega.soi.city.ac.uk/~dk708/pg1_3.htm#hqhttp://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.nationalgeographic.com/maps/%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.visa.com%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.geog.nott.ac.uk/~mather/vr.html%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.geog.nott.ac.uk/~mather/vr.html%27http://vega.soi.city.ac.uk/~dk708/pg1_3.htm#hqhttp://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.nationalgeographic.com/maps/%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.visa.com%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.geog.nott.ac.uk/~mather/vr.html%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.geog.nott.ac.uk/~mather/vr.html%27


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technologies: Geographical Information Systems, Virtual Reality and Computer-Supported Co-operative Work.

Web3D Consortium

Real-time GIS

With the availability of real-time positioning systems and cost-effective mobiletelecommunications, it has become possible to develop real-time GIS that

monitor, transmit, record and analyse the movement of mobile agents such as

vehicles, people or animals (telegeomonitoring). In transportation for example,many organisations need to monitor the position of their vehicles for scheduling

or safety reasons. Each mobile agents transmits positioning information to theappropriate control centre(s), where it is entered into a database of time-

stamped positions. Some applications can monitor the proximity of the mobile

agents to specified locations or advise on alternative routes based on traffic

reports. Imagine such applications in the context of an ambulance fleet of cars.Real-time GIS can also include location-based services, where a moving agentreceives information depending on its location (GMS - Geographic Messaging

Services), e.g., in tourism, giving and updating relevant details of attractions to

tourists as they approach different areas.

Reference:

Raper J. Multidimensional Geographic Information Science. London: Taylor andFrancis. 2000 [ISBN 0-7484-0507-0]
http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.web3d.org%27http://if%28confirm%28%27you%20are%20leaving%20mim%20centre%20pages%20and%20entering%20a%20web%20site%20maintained%20by%20another%20individual/organisation.%20Do%20you%20want%20to%20continue?%27))window.location=%27http://www.web3d.org%27

Spatial Information

Documents

Transcript of Spatial Information