An introduction to GIS

1. Introduction to Geographic
Information System (GIS)
By: Dr. Mohamed Yagoub Mohamed
E-mail: myagoub@hotmail.com
URL: http://www.angelfire.com/mo/yagoub

2. Introduction to Automated
Geography
Chapter 1
DeMers, M. N. ,1997. Fundamental of
Geographic Information Systems, John
Wiley & Sons. Inc, New York

3. Objectives
Define what a GIS is
Development of GIS
GIS, CAC, and CAD
Analytical capabilities of GIS
Analog mapping vs. automated GIS

4. 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

5. 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)

6. 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)

7. Taxonomic classification of GIS
(Fig. 1.1)
1. Spatial vs. nonspatial information
GIS is spatial
2. Nongeographic vs. geographic (GIS)
nongeographic - deals with geographic space but not
geocoded
3. Other GIS vs. LIS
Other GIS - nonland - economic, housing, market analysis
LIS - most often used type of GIS - management and
analysis of land surfaces
4. Non-parcel vs. parcel
non-parcel - natural resource management, habitat
evaluation, scientific investigation
parcel - land ownership (cadastral)

8. 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

9. 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)

10. Disadvantages of the manual methods
Long time for processing
Subject to human errors
Data can not be managed efficiently
Low cost/benefit ratio

11. Why GIS: Advantages of GIS
Time minimization
Accuracy improvement
Data can be managed efficiently
High cost/benefit ratio

12. Watersheds
Communities
Neighborhoods
Ecosystems
Context and Content
Patterns
Linkages
Trends
Seeing the WholeSeeing the Whole Managing PlacesManaging Places

13. 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/clas
ssched.htm DeMers
http://www.people.virginia.edu/~dc9a/classes/class
es.html Exercise-DeMers
http://www.utexas.edu/depts/grg/gcraft/about/tgis/t
able1.html Geographer's Craft project

14. GIS
Hardware
Software
Information
People
Components of GIS

15. 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)

16. 07/02/15
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

17. Hardware

19. Networking
Wide Area Network (WAN)
Remote

20. 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)

21. Software integration
DXF
IAC
DDERELATE
MS
Visual
Fox Pro
AutoCad ARC/INFO ArcView
Visual BasicVisual
MODFLOW
ODE

22. 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

23. 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

24. GIS Information
SPATIAL OBJECT
ATTRIBUTE SPATIAL
DBMS
GIS Database
(1)
SPATIAL OBJECT
ATTRIBUTE SPATIAL
DBMS
GIS Database
(2)

25. d GIS is a tool to see the whole
Social FactorsSocial Factors
BiodiversityBiodiversity
EngineeringEngineering
Land UseLand Use
EnvironmentalEnvironmental
ConsiderationsConsiderations

26. 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.

27. 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)

28. 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

29. 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

30. 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.

31. Coordinate system
Sphere -Globe
Three-Dimension
Spherical coordinate
Latitude (Ø) and longitude
(λ)
(Ø, λ)
Plane-Map
Two-Dimension
Cartesian
coordinate
(X,Y)
Distortion
distance,
area,
shape,
direction
Map projections express
3D in 2D

32. 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

33. 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

34. 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 both
Data analysis : Data layers can be joined to create new layers
containing the characteristic of both

35. 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)

36. 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.

37. 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

38. 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

39. Databases models
HIERARCHICAL
NETWORK
RELATIONAL (TABULAR)
OBJECT-ORIENTED

40. 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

41. 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

42. 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)

43. 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

44. Exercise 1
Principles of GIS

45. 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