why geoinformatics

7/28/2019 Why Geoinformatics

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GIS--What is it?No easy answer anymore!

Geographic Information information about places on the earths surface

knowledge about what is where when(Dont forget time!)

Geographic Information Technologies technologies for dealing with this information

Global Positioning Systems (GPS)

Remote Sensing (RM)

Geographic Information Systems (GIS)

GIS--whats in the S? Systems: the technology

Science: the concepts and theory

Studies: the societal context


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Geographic Information Technologies

(Tools)

Global Positioning Systems (GPS)

a system of earth-orbiting satellites which can

provide precise (100 meter to sub-cm.) location on

the earths surface (in lat/long coordinates or

equiv.)

Remote Sensing (RS)

use of satellites (and aircraft) to capture

information about the earths surface

Geographic Information Systems (GISy)

at a minimum, comprises a capability for input,

storage, manipulation and output of geographic

information

GPS and RS are sources of input data for aGISy.

A GISy provides for storing and manipulating GPS

and RS data.


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GI Systems, Science and Studies

Which will we do?

Systems technology for the acquisition and management of

spatial information

Science comprehending the underlying conceptual issues

of representing data and processes in space-time

the science (or theory and concepts) behind thetechnology

Studies understanding the social, legal and ethical issues

associated with the application of GISy and GISc


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Defining Geographic Information

Systems (GIS)

The common groundbetween information processing andthe many fields using spatial analysis techniques.

(Tomlinson, 1972)

A powerfulset of tools for collecting, storing, retrieving,

transforming, and displaying spatial data from the realworld. (Burroughs, 1986)

A computerised database management system for the

capture, storage, retrieval, analysis and display of spatial

(locationally defined) data. (NCGIA, 1987) A decision support system involving the integration of

spatially referenced data in a problem solving

environment. (Cowen, 1988)


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An Inelegant Definition for GISy

A system of integrated computer-basedtoolsfor end-to-endprocess ing(capture, storage,retrieval, analysis, display) of data usinglocation on the earths surfacefor

interrelation in support ofoperat ionsmanagement, decision making, and

science.

set of integrated tools for spatial analysis

encompasses end-to-end processing of data

capture, storage, retrieval, analysis/modification, display

uses explicit location on earths surface to relate data

aimed at decision support, as well as on-going operations

and scientific inquiry


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How GIS differs from Related Systems

DBMS--typical MIS data base contains implicit but not explicit locationalinformation

city, LGA,village, zip code, etc. but no geographical coordinates

is 100 N. High around the corner or across town from 200 E Main?

Automated Mapping (AM) --primarily two-dimensional display devices

thematic mapping (choropleth,etc such as GRAPH, business mappingsoftware) unable to relate different geographical layers (e.g location ofboreholes and villages)

automated cartography--graphical design oriented; limited database ability

Facility Management (FM) systems--

lack spatial analysis tools

CAD/CAM (computer aided design/drafting)--primarily 3-D graphic creation(engineering design) & display systems

dont reference via geographic location

CAD sees the world as a 3-D cube, GIS as a 3-D sphere

limited (if any) database ability (especially for non-spatial data)

scientific visualization systems--sophisticated multi-dimensional graphics, but:

lack database support lack two-dimensional spatial analysis tools


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what exists at a certain location?

where are certain conditions

satisfied?

what has changed in a place over

time? what spatial patterns exist?

what if this condition occurred at

Major Questions for a GIS?


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Why Study GIS? 80% of local government activities estimated to be

geographically based

plats, zoning, public works (streets, water supply), garbage collection,land ownership and valuation

a significant portion ofstate government has a geographicalcomponent

natural resource management

highways and transportation

businesses use GIS for a very wide array of applications

retail site selection & customer analysis

logistics: vehicle tracking & routing

natural resource exploration (petroleum, etc.)

precision agriculture

civil engineeringand construction scientific research employs GIS

geography, geology, botany

anthropology, sociology, economics, political science

Epidemiology, criminology


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Examples of Applied GIS Urban Planning, Management &

Policy

Zoning, subdivision planning

Land acquisition

Economic development

Code enforcement

Housing renovation programs

Emergency response

Crime analysis

Tax assessment Environmental Sciences

Monitoring environmental risk

Modeling stormwater runoff

Management of watersheds, floodplains,wetlands, forests, aquifers

Environmental Impact Analysis

Hazardous or toxic facility siting Groundwater modeling and

contamination tracking

Political Science

Redistricting

Analysis of election results

Predictive modeling

Civil Engineering/Utility

Locating underground facilities Designing alignment for freeways, transit

Coordination of infrastructure maintenance

Business

Demographic Analysis

Market Penetration/ Share Analysis

Site Selection Education Administration

Attendance Area Maintenance

Enrollment Projections

School Bus Routing

Real Estate

Neighborhood land prices Traffic Impact Analysis

Determination of Highest and Best Use

Health Care

Epidemiology

Needs Analysis

Service Inventory


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What GIS Applications Do:

manage, analyze, communicate

make possible the automation of activities involving geographicdata

map production

calculation of areas, distances, route lengths

measurement of slope, aspect, viewshed

logistics: route planning, vehicle tracking, traffic management allow for the integration of data hitherto confined to independent

domains (e.g property maps and air photos).

by tying data to maps, permits the succinct communication ofcomplex spatial patterns (e.g environmental sensitivity).

provides answers to spatial queries (how many AIDS infections

cases have been identified in villages around Kaduna town?) perform complex spatial modelling (what ifscenarios for

transportation planning, disaster planning, resource management,utility design)


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GIS System Architecture and

Components

Data Input Geographic Database

Query Input

Output:

Display andReporting

Transformationand Analysis


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The GIS Data Model:Purpose

allows geographic featuresin real

world locationsto be digitally

represented and stored in a databaseso that they can be abstractly

presented in map(analog) form, and

can also be worked with and

manipulated to address someproblem


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Representing Data with Rasterand

VectorModels

Raster Model

area is covered by grid (usually) equal-sized cells

cells often calledpixels (pictureelements); raster data often calledimage data

attributes are recorded by assigningeach cell a single value based on themajority feature (attribute) in the cell,such as land use type.


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Raster Data Model

DN = 2 = riverDN = 20 = settlement

DN = 44 = farmland

DN = 89 = forest


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Raster and Vector


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The fundamental concept of vector GIS is that all

geographic features in the real world can berepresented either as:

points or dots (nodes): Taps, trees, poles, wells,

airports, cities

lines (arcs): streams, streets, sewers, roads, tracks

areas (po lygons): land parcels, cities, counties, forest,

rock type


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Vector Data Model


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0 1 2 3 4 5 6 7 8 9

0 R T

1 R T

2 H R

3 R

4 R R

5 R

6 R T T H

7 R T T

8 R

9 R

Real World

Vector RepresentationRaster Representation

Concept of

Vector and Raster

line

polygon

point


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Projection, Scale, Accuracy and Resolutionthe key properties of spatial data

Projection: the method by which the curved 3-D surface of the earth isrepresented by X,Y coordinates on a 2-D flat map/screen

distortion is inevitable

Scale: the ratio of distance on a map to the equivalent distance on theground

in theory GIS is scale independent but in practice there is an implicitrange of scales for data output in any project

Accuracy: how well does the database info match the real world

Positional: how close are features to their real world location?

Consistency: do feature characteristics in database match those inreal world

is a road in the database a road in the real world?

Completeness: are all real world instances of features present in the

database? Are all roads included.

Resolution: the size of the smallest feature able to be recognized for raster data, it is thepixelsize

The tighter the specif ication, the higher the cost.


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The GIS Data Model: Implementation

Geographic Integration of Information

Digital Orthophoto

Streets

Hydrography

Parcels

Buildings

Zoning

Utilities

Administrative Boundaries

Data is organized by layers, coverages orthemes

(synonymous concepts), with each theme representing a

common feature.

Layers are integrated using explicit location on the earths

surface, thus geographic location is the organizing principle.


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The GIS Model: example

roads

hydrology

topography

Here we have three layers orthemes:

--roads,

--hydrology (water),

--topography (land elevation)They can be related because precise geographic

coordinates are recorded for each theme.

longitude

longitude

longitude

Layers are comprised of two data typesSpatial data which describes location (where)

Attribute data specifing what, how much,when

Layers may be represented in two ways:

in vectorformat as points and lines

in raster(image) format as pixels

All geographic data have 4 properties:

projection, scale, accuracy and resolution


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Spatial and Attribute Data Spatial data (where)

specifies location Attribute (descriptive) data (what, how much, when)

specifies characteristics at that location, natural orhuman-created

stored in a data base table

GIS systems traditionally maintain spatial and attribute dataseparately, then join them for display or analysis

for example, in ArcView, theAttributes of table isused to link a shape file (spatial structure) with a database table containing attribute information in order todisplay the attribute data


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Attribute Data

S ft f GIS


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Software for GIS: The Main Players

ESRI, Inc., Redlands, CA

clear market leader with about a third of the market

originated commercial GIS with their ArcInfo product in 1981 privately owned by Jack Dangermond, a legend in the field

Strong in gov., education, utilities and business logistics

MapInfo, Troy N.Y.

Aggressive newcomer in early 1990s, but now well-established.

Strong presence in business, especially site selection & marketing, andtelecom

Intergraph (Huntsville, AL) origins in proprietary CAD hardware/software

Older UNIX-based MGE (Modular GIS Environment) evolved from CAD

new generation GeoMedia product based on NT is now their main focus

strong in design, public works, and FM (facilities management)

Bentley Systems (Exton, PA)

MicroStation GeoGraphics, originally developed with Intergraph, is nowtheir exclusive and main product..

Strong in engineering; advertises itself as geoengineering

Autodesk (San Rafael, CA)

Began as PC-based CAD, but now the dominant CAD supplier

First GIS product AutoCAD Mapintroduced in 1996

Primarily small business/small city customer base

The main two

pure GIS

companies.

S ft f GIS th l


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Software for GIS: other playersVector GIS

SmallworldSystems

(Englewood, CO) first to use OO (early

90s), but failed tocompete asestablished vendorsdid same

Purchased by GE in

2000 emphasis on FM &

utilities

Manifold(CDA InternationalCorp):

low cost, but lowmarket share

Maptitude(Caliper Corp,Newton, MA):

another low cost one

Raster GIS

ERDAS/Imagine

long established leader acquired by Leica Geosystems in 2001

ER MAPPER

aggressive newcomer originating in Australia

Envi,

relative newcomer, radar specialization

acquired by Kodak in 2000

PCI--Geomatica

long-term Canadian player

CARIS

newer Canadian entry

GRASS (Rutgers Univ.) Classic old-timer originally developed by US

Army Construction Engineering ResearchLab(CERL) in Champaign, IL;

army ended dev. & support in 1996 butassumed by Baylor University.

IDRSI (Clark Univ)

pioneering, university-developed package


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why geoinformatics

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