Chap1 introduction to geographic information system (gis)
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Transcript of Chap1 introduction to geographic information system (gis)
Introduction to Geographic Information System (GIS)
By: Dr. Mohamed Yagoub Mohamed
E-mail: [email protected]
URL: http://www.angelfire.com/mo/yagoub
Introduction to Automated Geography
Chapter 1DeMers, M. N. ,1997. Fundamental of Geographic Information Systems, John Wiley & Sons. Inc, New York
Objectives
Define what a GIS is Development of GIS GIS, CAC, and CAD Analytical capabilities of GIS Analog mapping vs. automated GIS
What is GIS? Tools that allow for the processing of
spatial data into information Not a precise or comprehensive definition Lack of definition results in misconceptions
about GIS i.e., CAC, CAD and GIS are all the same
– CAC -Computer Assited Cartography: create maps from graphical objects combined with descriptive attributes (size, color), lacks analytical capability
– CAD -Computer Aided Design: create maps from graphical objects (no attributes)-Architecture
– GIS - Adds the analytical capabilities the other 2 lack
What is GIS?
GIS is any computerized information system that is designed to store, manipulate, retrieve, analyze, and display spatially referenced data.
Land Information System (LIS) is typical to GIS, but related primarily to large scale and parcel-based system such as Automated Mapping and Facilities Management (AM/FM)
What is GIS?
The major difference between Computer Mapping System (CMS), Computer Aided Design (CAD), and GIS is that the latter performs functions related to cartography (graphic) while the former has additional component of data analysis (graphic+ attribute)
Taxonomic classification of GIS (Fig. 1.1)
1. Spatial vs. nonspatial informationGIS is spatial
2. Nongeographic vs. geographic (GIS)nongeographic - deals with geographic space but not
geocoded
3. Other GIS vs. LISOther GIS - nonland - economic, housing, market analysisLIS - most often used type of GIS - management and
analysis of land surfaces
4. Non-parcel vs. parcelnon-parcel - natural resource management, habitat
evaluation, scientific investigationparcel - land ownership (cadastral)
GIS Development
1960s Computing comes of age 1970s GIS software evolves rapidly 1980s GIS software advances significantly Personal computers introduced Public domain data becomes available 1990s Application development 2000 Web-based GIS
Information system
Information System (IS)
Spatial IS (x,y,z,t)
Non-spatial IS e.g. accounting
Parcel-based(LIS)
Other e.g.Forest (GIS)
Disadvantages of the manual methods
Long time for processing
Subject to human errors
Data can not be managed efficiently
Low cost/benefit ratio
Why GIS: Advantages of GIS
Time minimization
Accuracy improvement
Data can be managed efficiently
High cost/benefit ratio
Watersheds Communities Neighborhoods Ecosystems
Context and Content
Patterns Linkages Trends
Seeing the WholeSeeing the Whole Managing PlacesManaging Places
GIS web sites www.gislinx.com -100s GIS sites www.esri.com -ESRI site www.tandf.co.uk -IJGIS journal www.amazon.com -GIS references http://www.iupui.edu/~jeswilso/g438/ DeMers http://www.csupomona.edu/~sagarver/GEO442/
classsched.htm DeMers http://www.people.virginia.edu/~dc9a/classes/
classes.html Exercise-DeMers http://www.utexas.edu/depts/grg/gcraft/about/tgis/
table1.html Geographer's Craft project
GIS
Hardware
SoftwareInformation
People
Components of GIS
People
People are essential part of GIS Issues related to people are training,
education, management, law, security, data sharing and coordination
GIS budget (cost of data, hardware, software, and maintenance)
04/15/23
Hardware
Input (Keyboard, mouse, digitizer, scanner, sound)
Processing (Central processing unit -CPU) Pentium II (400 MHz)
Storage (Magnetic and optical media -Hard disk 4GB, CD-ROM-650MB, Floppy 1.4 MB, Zip 100 MB)
Output (Screen, sound system, printer, plotter) www.hp.com, www.calcomp.com
Hardware
Networking
Wide Area Network (WAN)
Remote
Software
Operating System (OS) - WindowsY2K/NT
Graphic software (CAD, Microstation)
Database software (dBASE, Oracle)
Statistical packages (SPSS, SAS, Minitab)
Word processing (Ms Word, Word Perfect)
Image processing (IDRISI, ER Mapper)
GIS systems (Arc/Info, ArcView, MapInfo)
Presentation (Ms PowerPoint, Coral Draw)
Software integration
DXFIAC
DDERELATE
MSVisualFox Pro
AutoCad ARC/INFO ArcView
Visual BasicVisualMODFLOW
ODE
Selection of a GIS system
Selection of a GIS systems depends on many factors e.g. the budget, purpose, and functions of the system
For small companies and educational institutions, low cost systems are suitable e.g. ArcView and IDRISI
For big companies a GIS system that provides multi-functions is necessary this may be at a high cost e.g. Arc/Info NT 8.0
Information
There are two basic types of map information in a GIS: Spatial and Aspatial (DESCRIPITIVE-attribute)
Spatial refers to geographic features that are represented as POINTS, LINES, and POLYGONS
Aspatial or Descriptive refers to TABULAR DATA which records characteristics of the geographic features
GIS Information
SPATIAL OBJECT
ATTRIBUTE SPATIAL
DBMS
GIS Database
(1)
SPATIAL OBJECT
ATTRIBUTE SPATIAL
DBMS
GIS Database
(2)
d GIS is a tool to see the whole
Social FactorsSocial Factors
BiodiversityBiodiversity
EngineeringEngineering
Land UseLand Use
EnvironmentalEnvironmentalConsiderationsConsiderations
4 Sub-system definition of GIS (Tables 1.2-1.6)
1. A data input subsystem that collects and processes spatial data from various sources.
2. A data storage and retrieval subsystem that organizes data in a manner that allows retrieval, updating, and editing.
3. A data manipulation and analysis subsystem that performs tasks on the data (classification, modeling functions).
4. A reporting subsystem that displays all or part of the database in tabular, graphic or map form.
GIS functions
Data acquisition (spatial and non-spatial)
Data processing (data management)
Data analysis (Spatial & statistical analysis)
Data storage (Store data more efficiently)
Data output (Maps, graphs, tables, reports)
Subsystem Definition of GIS
Data Input Subsystem - allows user to import, create, and edit spatial and tabular data
Data Storage and Retrieval Subsystem - provides storage, retrieval, updating and editing capabilities
Data Analysis Subsystem - provides to tools to examine characteristics of the data and model building capabilities
Reporting Subsystem - provides tools for designing maps, graphics, text, and tabular output
Data acquisition
GIS includes Spatial and descriptive data
(Attribute)
Spatial data can be obtained from maps
images or digital files
Attribute data can be obtained from reports,
statistical outcomes, and written documents
Data format The spatial data can be store in vector or raster
format Vector format represents data in a series of (X,Y)
coordinates Raster format represent data in a series of columns
and rows-Matrix (Pixel, cell) Vector data are accurate and takes less storage,
but take long time e.g. digitization Raster data are inaccurate and takes large storage,
but takes short time e.g. scanning
Coordinate system
Sphere -GlobeThree-DimensionSpherical coordinateLatitude (Ø) and longitude ()(Ø, )
Plane-MapTwo-DimensionCartesian coordinate(X,Y)
Distortion distance, area,shape, direction
Map projections express3D in 2D
Data processing
Once the data is acquired the next step is to put it in a digital format.
Data processing may include conversion of the data to a common coordinate system.
Checking the accuracy of the spatial and attribute data
Linking the spatial and attribute data
Data analysis Analysis is considered as the most important
tool in GIS (Heart of GIS) . Spatial and statistical analysis can be done. Spatial analysis includes map overlay,
buffering, and map algebra Statistical analysis includes e.g. determination
of maximum, minimum, and average values New data can be derived from existing data
Soil Types
+
Crop Productivity(bushels/acre)
Combined Layers
When data coundaries betwen layers don’t match, the layers can be joined,creating a new layer containing the characteristics of bothData analysis : Data layers can be joined to create new layers containing the characteristic of both
Data storage
GIS data can be store in different media. For example, Magnetic or optical media e.g. HD, floppy, and CD-ROM.
Backup of GIS data must be done on regular basis to a void loss of data due to hardware failure, virus, or data corruption.
Security measures must be taken e.g. at computer level (access right) and physical level (good locking and guard)
Data output: Visualization
Output from GIS can be in hardcopy or softcopy and in different formats.
Maps (2D, 3D) showing location and description.
Tables showing detailed description. Reports showing summary of information. Different forms of graphs including bar, pie,
and line.
Spatial data acquisition
There are two methods for spatial data acquisition
Primary methods Surveying, Photogrammetry, GPS, and
Remote Sensing
Secondary methods
Digitization, Automatic line following,
and scanning
Aspatial: Tabular Databases
Tabular data (attribute, descriptive data) are essential part of GIS
Attribute data can be obtained from reports or written documents
Different database systems can be used for attribute input e.g. dBASE, Oracle, Informix
Most database systems are based on arranging attribute data in a form of tables, these tables consists of fields and records
Databases models
HIERARCHICAL
NETWORK
RELATIONAL (TABULAR)
OBJECT-ORIENTED
Database operations
Databases allow users to build, sort, delete, edit, select, mathematically manipulate, and update information through the use of a Data Definition Language (DDL) and data manipulation Language (DML)
DML (query language) allows users to ask questions about the database in a standardized way (Structured Query Language-SQL) e.g. find all states with area > 5000 sq Km
Standards for GIS
Open GIS consortium (OGC) started in 1995 (OLE/COM)
Eurog (developed in Europe) Spatial Data Transfer Standards
(STDS) developed in the US
Impact of the Internet on GIS
Exchange and Sharing of ideas via- electronic
mail (e-mail) and online lists
Online forum (video conferencing)
Data transfer (File Transfer Protocol- FTP)
Browsing (web sites)
GIS Applications
Foresters - timber inventory Fire, police, ambulance - 911 and
emergency vehicle routing Military - logistics and battle plans Telecommunications - siting cellular
transmission towers Local to national scale government - city
planning, zoning, natural resources, etc. Academia - used by many other
disciplines outside of geography
Exercise 1
Principles of GIS
Section A: Principles of GIS Maximum 5 pages
1. Define GIS
2. What is the difference between automated cartography and GIS
3. What is the difference between GIS and LIS
4. Discuss briefly the main components of GIS( People, Data, Hardware, and Software)
5. Write one page about the impact of internet on GIS
6. List five web sites that you have visited