Matakuliah
Tahun
Versi
: T0234 / Sistem Informasi Geografis
: 2005
: 01/revisi 1
Pertemuan 11
Desain Sistem
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Learning Outcomes
Pada akhir pertemuan ini, diharapkan
mahasiswa akan mampu :
• Mendesain SIG sesuai dengan hasil
analisis yang telah dilakukan (C5, TIK11)
2
Outline Materi
• Materi 1 : Conceptual Data Model
• Materi 2 : Physical Data Model
• Materi 3 : Cartographic Modelling
3
Desain Sistem
• Preliminary Design
Menghasilkan rancangan yang bersifat global.
• Detailed Design
Menghasilkan rancangan detil hingga semua
modul (kelas), tipe (struktur) data, fungsi &
prosedurnya (baik methods yang berfungsi
sebagai interface maupun yang terdapat di
dalam setiap modul) terdefinisi.
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Conceptual Data Model
• The Conceptual Data Model is a high-level
view that is independent of the computer
system.
• The Conceptual Data Model adds spatial
detail to the rich picture by including
elements of spatial form & spatial process.
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Conceptual Data Model (2)
•
1.
2.
3.
4.
Bell & Wood-Harper (1992) provide a useful checklist for the
development of a Conceptual Model :
Develop a rich picture & root definition : Everyone associated with the
problem should agree upon these. They are used to focus the aims &
direction for the project.
Create a list of actions the system must be able to perform : In the
house-hunting example, these actions may include permitting users to
select neighborhood characteristics such proximity to schools, railway
stations and shops, & allowing users to weight these characteristics in
terms of their relative importance. This actions are known as activities.
Identify a list of system inputs & outputs : In the house-hunting
example, the data sources would include street networks, public
transport routes & the location of properties for sale. Outputs might be
a list, or map, of properties meeting home buyers’ criteria.
Group activities, inputs & outputs into a logical, chronological order :
Arrows symbolizing some form of action are used to join activities
together. Example : The combination of data from different sources
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could be effectively represented in this way.
Physical Data Model
* The Physical Data Model describes the
organization of data in the computer.
* The Physical Data Model is concerned with how
to represent the conceptual model within the
computer.
* Detailed about the spatial data model (raster or
vector), the the appropriate data structure and
analysis scheme are included in the physical
data model.
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Cartographic Modelling
• A generic way of expressing and
organizing the methods by which spatial
variables,and spatial operations are
selected and used to develop a GIS data
model.
• A geographic data processing methodology that views maps (or any spatial data
layer) as variables in algebraic equation.
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Cartographic Modelling (2)
4 Stages in the development of a cartographic model
(Burrough, 1986) :
1.
2.
3.
4.
Identify the map layers or spatial data sets required.
Use natural language to explain the process of moving
from the data available to a solution.
Draw a flowchart to represent graphically the process in
step 2. In the context of map algebra this flowchart
represents a series of equations you must solve in order to
produce the answer to your spatial query.
Annotate this flowchart with the commands necessary to
perform these operations within the GIS you are using.
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Cartographic Modelling (3)
A simple map algebra equation : x + y = z
Where x= Road map
y= Rail map
z= Communication map
+= The spatial overlay operation ‘union’
Graphical Representation :
Road map
+ Rail map
Example
Keyword
:
-Spread
-Overlay
-Extract
= Communication map
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Cartographic Modelling (4)
Others algebra equation :
1. From land use extract countryside
a-b=c
2. From road map spread road by
distance : (d – e) + f = g
where :
a : land use map
b : urban land use map
c : country side
where :
d : road map
e : portion of map which is not road
f : zone of spread for specified
distance either side of road
g : proximity to road map
3. From house status extract houses
for sale : h - i = j
4. Overlay houses for sale in country
side away from roads
j+k=l
where :
j : houses for sale
k: countryside away from roads
l : houses for sale & countryside
away from roads
where :
h : house status map
i : houses not for sale
j : houses for sale
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Cartographic Modelling (5)
Eq1 Extract
Extract
Land use
Countryside
Eq2 Spread
Road map
Countryside away
from roads
Proximity to road
Eq3 Extract
Houses
Countryside/
Proximity to road
Houses for sale
Only houses
for sale in
countryside
away from
roads
Houses for sale in countryside
away from roads
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Design Issues in Practice
•
•
•
•
•
•
•
Data Availability
Data Encoding
Analysis Methods Available
Output Requirements
Software Availability
Time Available
Resources Available
Details at Page 250-251, “An Introduction to GIS”, Ian Heywood, et al
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Penutup
• Mahasiswa diharapkan telah mampu mendesain SIG sesuai dengan hasil analisis
yang telah dilakukan .
• Model desain dapat divisualisasikan dengan
Cartographic Model.
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