Chapter3 application requirements

GEOGRAPHIC INFORMATION SYSTEM II
(SUG554)
Assoc. Prof. Sr. Zamani Bin Ismail
Room B501
Contact: 03-55444528 or 019-3605218

Recap - Choosing a GISRecap - Choosing a GIS
►Involves 4 stagesInvolves 4 stages
 Analysis of requirement,Analysis of requirement,
 Specification of requirements,Specification of requirements,
 Evaluation of alternativesEvaluation of alternatives
 Implementation of systemImplementation of system

Recap - Steps in GIS acquisitionRecap - Steps in GIS acquisition

How can
I use a
GIS?
Need to make a map
Need to answer a query
Need to save
important data
Need to describe
an activity
Prepare Application
Description
Add to Master Data List
Prepare Data
Flow Diagram
Name of Government
Geographic Information System
Requirements Analysis
Data Flow Diagram
Application Identification #:
Application Name:
Department:
Defined by:
Prepared by: Approved by: Date:
Process Description: Data Flow Diagram or Flow Chart
Name of Government
GIS Application Description
Application Name:
Department:
Defined by:
Type of Application:
Display Display/Map Scale:
Query Query Key:
Query & Display Response Time:
Map Analysis Frequency:
Spatial Model
Data Required:
Features (entities): Attributes:
Purpose and Description:
Master Data List
Entity Attributes Spatial
Object
Street_segment name, address_range Line
Street_intersection street,_names Line
Parcel section_block_lot#, Polygon
owner_name, owner_address,
site_address, area, depth,
front_footage, assessed_value,
last_sale_date, last_sale_price,
size (owner_name,
owner_address,
assessed_value as of previous
January 1st)
Building building_ID, date_built, Footprint
building_material,
building_assessed_value
Occupancy occupant_name, None
occupant_address,
occupancy_type_code
Street_segment name, type, width, length, Polygon
pavement_type
Street_intersection length, width, traffic_flow_conditions Polygon
intersecting_streets
Water_main type, size, material, installation_date Line
Valve type, installation_date Node
Hydrant type, installation_date, pressure Node
last_pressure_test_date
Service name, address, type, invalid_indicator None
Soil Soil_code, area Polygon
Wetland wetland_code, area Polygon
Floodplain flood_code, area Polygon
Traffic_zone zone_ID#, area Polygon
Census_tract tract#, population
Polygon
Water_district name, ID_number Polygon
Zoning zoning_code, area Polygon
Documenting Needs of aDocumenting Needs of a
Potential GIS UserPotential GIS User

Results of Needs AssessmentResults of Needs Assessment
ExampleExample
Application
Description
List of
Important
Data
Data Flow
Diagram
Name of Government
Data Flow Diagram
Application Name:
Department:
Defined by:
Name of Government
Application Name:
Department:
Defined by:
Query Query Key:
Spatial Model
Data Required:
Master
Data List
List of GIS
Functions
Master Data List
Entity Attributes Spatial
Object
Street_segment name, address_range Line
Street_intersection street,_names Line
Parcel section_block_lot#, Polygon
owner_name, owner_address,
site_address, area, depth,
front_footage, assessed_value,
last_sale_date, last_sale_price,
size (owner_name,
owner_address,
assessed_value as of previous
January 1st)
Building building_ID, date_built, Footprint
building_material,
building_assessed_value
Occupancy occupant_name, None
occupant_address,
occupancy_type_code
Street_segment name, type, width, length, Polygon
pavement_type
Street_intersection length, width, traffic_flow_conditions Polygon
intersecting_streets
Water_main type, size, material, installation_date Line
Valve type, installation_date Node
Hydrant type, installation_date, pressure Node
last_pressure_test_date
Service name, address, type, invalid_indicator None
Soil Soil_code, area Polygon
Wetland wetland_code, area Polygon
Floodplain flood_code, area Polygon
Traffic_zone zone_ID#, area Polygon
Census_tract tract#, population
Polygon
Water_district name, ID_number Polygon
Zoning zoning_code, area Polygon

2. User requirements analysis/needs2. User requirements analysis/needs
assessmentassessment
► Clear articulation of user needs is essential to assist the developmentClear articulation of user needs is essential to assist the development
of an appropriate list of requirements for a GIS.of an appropriate list of requirements for a GIS.
► Analysis focuses onAnalysis focuses on
 Who is using the systemWho is using the system
 What information is presently being usedWhat information is presently being used
 How the source is being collected, stored & maintainedHow the source is being collected, stored & maintained
► the necessary info can be obtained throughthe necessary info can be obtained through
 InterviewsInterviews
 DocumentationDocumentation
 ReviewsReviews
 WorkshopsWorkshops
► The report for this phase should be in the forms of workflows, lists ofThe report for this phase should be in the forms of workflows, lists of
information sources and current operation cost.information sources and current operation cost.

2. User requirements analysis/needs2. User requirements analysis/needs
assessmentassessment
► Clear articulation of user needs is essential to assist the development of anClear articulation of user needs is essential to assist the development of an
appropriate list of requirements for a GIS.appropriate list of requirements for a GIS.
► Analysis focuses onAnalysis focuses on
 Who is using the systemWho is using the system
 What information is presently being usedWhat information is presently being used (Applications requirements)(Applications requirements)
 How the source is being collected, stored & maintainedHow the source is being collected, stored & maintained
► the necessary info can be obtained throughthe necessary info can be obtained through
 InterviewsInterviews
 DocumentationDocumentation
 ReviewsReviews
 WorkshopsWorkshops
► The report for this phase should be in the forms of workflows, lists ofThe report for this phase should be in the forms of workflows, lists of
information sources and current operation cost.information sources and current operation cost.

GIS applicationsGIS applications
►GIS applicationsGIS applications - these will be- these will be taskstasks thatthat
can be performed by the GIS when a usercan be performed by the GIS when a user
requires them, such as preparing a map,requires them, such as preparing a map,
processing a query, or conducting someprocessing a query, or conducting some
particular GIS analysis.particular GIS analysis.

LOCAL GOVERNMENT USESLOCAL GOVERNMENT USES
OF GISOF GIS
The use of geographic information systemsThe use of geographic information systems
by local government falls into five majorby local government falls into five major
categories:categories:
 BrowseBrowse
 Simple display (automated mapping);Simple display (automated mapping);
 Query and display;Query and display;
 Map analysis; andMap analysis; and
 Spatial modeling.Spatial modeling.

BrowseBrowse
This function is equivalent to the human act ofThis function is equivalent to the human act of
reading a map to find particular features orreading a map to find particular features or
patterns. Browsing usually leads to identificationpatterns. Browsing usually leads to identification
of items of interest and subsequent retrieval andof items of interest and subsequent retrieval and
manipulation by manual means. For single maps,manipulation by manual means. For single maps,
or relatively small areas, the human brain is veryor relatively small areas, the human brain is very
efficient at browsing. However, as data volumesefficient at browsing. However, as data volumes
increase, automated methods are required toincrease, automated methods are required to
effectively extract and use information from theeffectively extract and use information from the
map.map.

OF GISOF GIS
 BrowseBrowse
 Simple display (automated mapping)Simple display (automated mapping);;

Simple DisplaySimple Display
This GIS function is the generation of a mapThis GIS function is the generation of a map
or diagram by computer. Such maps andor diagram by computer. Such maps and
diagrams are often simple reproduction ofdiagrams are often simple reproduction of
the same maps used in a previous manualthe same maps used in a previous manual
oriented GIS environment. Examples of thisoriented GIS environment. Examples of this
type of use are preparation of a 1:1000-type of use are preparation of a 1:1000-
scale town map, a sketch of an approvedscale town map, a sketch of an approved
site plan, maps of census data, etc.site plan, maps of census data, etc.

OF GISOF GIS
 BrowseBrowse
 Query and displayQuery and display;;

Query And DisplayQuery And Display
This function supports the posing of specific questions to aThis function supports the posing of specific questions to a
geographic database, with the selection criteria usuallygeographic database, with the selection criteria usually
being geographic in nature. A typical simple query wouldbeing geographic in nature. A typical simple query would
be: "draw a map of the location of all new residential unitsbe: "draw a map of the location of all new residential units
built during 1989" A more complex query might be: "drawbuilt during 1989" A more complex query might be: "draw
a map of all areas within the town where actual newa map of all areas within the town where actual new
residential units built in 1989 exceeds growth predictions."residential units built in 1989 exceeds growth predictions."
Such a query could be part of a growth managementSuch a query could be part of a growth management
activity within the town. Queries may be in the form ofactivity within the town. Queries may be in the form of
regular, often asked questions or may be ad hoc, specificregular, often asked questions or may be ad hoc, specific
purpose questions. The ability to respond to a variety ofpurpose questions. The ability to respond to a variety of
questions is one of the most useful features of a GIS in itsquestions is one of the most useful features of a GIS in its
early stages of operation. In the long run, other moreearly stages of operation. In the long run, other more
sophisticated applications of the GIS may have a highersophisticated applications of the GIS may have a higher
value or benefit, but to achieve these types of benefits,value or benefit, but to achieve these types of benefits,
users must be familiar with the GIS and its capabilities.users must be familiar with the GIS and its capabilities.
Such familiarization is achieved through the use of a GISSuch familiarization is achieved through the use of a GIS
for the simpler tasks of query and display.for the simpler tasks of query and display.

OF GISOF GIS
 BrowseBrowse
 Map analysisMap analysis; and; and

Map Analysis (Map Overlay)Map Analysis (Map Overlay)
This involves using the analytical capabilities ofThis involves using the analytical capabilities of
GIS to define relationships between layers ofGIS to define relationships between layers of
spatial data. Map analysis is the super-impositionspatial data. Map analysis is the super-imposition
of one map upon another to determine theof one map upon another to determine the
characteristics of a particular site (e.g., combiningcharacteristics of a particular site (e.g., combining
a land use map with a map of flood prone areas toa land use map with a map of flood prone areas to
show potential residential areas at risk forshow potential residential areas at risk for
flooding). Map analysis (often termed overlay orflooding). Map analysis (often termed overlay or
topological overlay) was one of the first real usestopological overlay) was one of the first real uses
of GIS. Many government organizations,of GIS. Many government organizations,
particularly those managing natural resources,particularly those managing natural resources,
have a need to combine data from different mapshave a need to combine data from different maps
(vegetation, land use, soils, geology, ground(vegetation, land use, soils, geology, ground
water, etc.).water, etc.).

Map Analysis (Map Overlay)Map Analysis (Map Overlay)
The overlay function was developed to accomplish theThe overlay function was developed to accomplish the
super-imposition of maps in a computer. The data aresuper-imposition of maps in a computer. The data are
represented as polygons, or areas, in the GIS data base,represented as polygons, or areas, in the GIS data base,
with each type of data recorded on a separate "layer." Thewith each type of data recorded on a separate "layer." The
combination of layers is done by calculating the logicalcombination of layers is done by calculating the logical
intersection of polygons on two or more map layers. Inintersection of polygons on two or more map layers. In
addition to combining multiple "layers" of polygon-typeaddition to combining multiple "layers" of polygon-type
data, the map overlay function also permits thedata, the map overlay function also permits the
combination of point data with area data (point-in-polygon).combination of point data with area data (point-in-polygon).
This capability would be very useful in a town for combiningThis capability would be very useful in a town for combining
street addresses (from the Assessor's files) with other datastreet addresses (from the Assessor's files) with other data
such as parcel outlines, census tract, environmental areas,such as parcel outlines, census tract, environmental areas,
etc. Many facility siting problems, location decisions, andetc. Many facility siting problems, location decisions, and
land evaluation studies have successfully used thisland evaluation studies have successfully used this
procedure in the past.procedure in the past.

OF GISOF GIS
 BrowseBrowse
 Spatial modelingSpatial modeling..

Spatial ModelingSpatial Modeling
This application is the use of spatial models or otherThis application is the use of spatial models or other
numerical analysis methods to calculate a value of interest.numerical analysis methods to calculate a value of interest.
The calculation of flow in a sewer system is an example ofThe calculation of flow in a sewer system is an example of
spatial modeling. Spatial modeling is the most demandingspatial modeling. Spatial modeling is the most demanding
use of a GIS and provides the greatest benefit. Most spatialuse of a GIS and provides the greatest benefit. Most spatial
modeling tasks are very difficult to perform by hand and aremodeling tasks are very difficult to perform by hand and are
not usually done unless a computerized system, such as anot usually done unless a computerized system, such as a
GIS, is available. These models allow engineers andGIS, is available. These models allow engineers and
planners to evaluate alternate solutions to problems byplanners to evaluate alternate solutions to problems by
asking "what if" type questions. A spatial model canasking "what if" type questions. A spatial model can
predict the result expected from a decision or set ofpredict the result expected from a decision or set of
decisions. The quality of the result is only as good as thedecisions. The quality of the result is only as good as the
model, but the ability to test solutions before decisionsmodel, but the ability to test solutions before decisions
have to be made usually provides very useful informationhave to be made usually provides very useful information
to decision makers. Once again, this type of use of a GISto decision makers. Once again, this type of use of a GIS
will evolve over time, as the GIS is implemented and used.will evolve over time, as the GIS is implemented and used.

Documenting applicationDocumenting application
requirementsrequirements
Name of Government
Application Name:
Department:
Defined by:
Query Query Key:
Spatial Model
Data Required:

Map DisplayMap Display
Name of Government
Map Display
Application Name:
Department:
Defined by:
Graphical Output Sample: Screen: Hard Copy:
Symbols/Legend

Table DisplayTable Display
Name of Government
Table Display
Application Name:
Department:
Defined by:
Report Layout/Format: Screen: Hard Copy:
HEADINGS
SUB-HEADINGS
SUB-TOTALS/TOTALS:

Data Flow DiagramData Flow Diagram
Name of Government
Data Flow Diagram
Application Name:
Department:
Defined by:

Entity-Relationship DiagramEntity-Relationship Diagram
Name of Government
Entity-Relationship Diagram
Application Name:
Department:
Defined by:
Data Description: Entity - Relationship Diagram
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Chapter3 application requirements

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