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Pertemuan 11Desain Sistem

Matakuliah : T0234 / Sistem Informasi Geografis

Tahun : 2005

Versi : 01/revisi 1

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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)

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Outline Materi

• Materi 1 : Conceptual Data Model

• Materi 2 : Physical Data Model

• Materi 3 : Cartographic Modelling

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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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• Bell & Wood-Harper (1992) provide a useful checklist for the development of a Conceptual Model :

1. 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.

2. 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.

3. 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.

4. 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 could be effectively represented in this way.

Conceptual Data Model (2)

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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 methodo-logy 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. Identify the map layers or spatial data sets required.

2. Use natural language to explain the process of moving from the data available to a solution.

3. 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.

4. 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 = Communication map

Example Keyword :-Spread-Overlay-Extract

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Cartographic Modelling (4)Others algebra equation :

1. From land use extract countryside

a - b = c

where :a : land use mapb : urban land use mapc : country side

2. From road map spread road by distance : (d – e) + f = g

where :d : road mape : portion of map which is not

roadf : zone of spread for specified

distance either side of roadg : proximity to road map

3. From house status extract houses for sale : h - i = j

where :h : house status mapi : houses not for salej : houses for sale

4. Overlay houses for sale in country side away from roads

j + k = lwhere :j : houses for salek: countryside away from roadsl : houses for sale & countryside

away from roads

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Cartographic Modelling (5)

Land use Countryside

Road map Proximity to road

Houses Houses for sale

Countryside away from roads

Countryside/ Proximity to road

Houses for sale in countryside away from roads

Only houses for sale in countryside away from roads

Eq1 Extract

Eq2 Spread

Eq3 Extract

Overlay

Overlay

Extract

Overlay

Overlay

Extract

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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 men-desain SIG sesuai dengan hasil analisis yang telah dilakukan .

• Model desain dapat divisualisasikan dengan Cartographic Model.