Table of Contents SuperGeo Technologies Inc. SuperGIS 3 Product Diagram ............. 1 Chapter 1: What’s GIS? ....................................................................... 2 Chapter 2: Why GIS? ........................................................................... 4

2.1 Enhance the value of geographic information............................... 4 2.2 More precise decisions .................................................................. 4 2.3 Produce maps ............................................................................... 4

Chapter 3: What is GIS used for? ........................................................ 6 3.1 Where are the locations? ............................................................... 6 3.2 Visualized display of numbers ...................................................... 7 3.3 Density Maps ............................................................................... 8 3.4 Buffer analysis .............................................................................. 9 3.5 Time Changes ............................................................................... 11

Chapter 4: How To Perform GIS Analysis ........................................ 12 4.1 Problem design ............................................................................ 12 4.2 Data collection .............................................................................. 12 4.3 Evaluating analysis methods ....................................................... 13 4.4 Processing data ............................................................................ 14 4.5 Exporting results ........................................................................... 15

Chapter 5: GIS Software ...................................................................... 16 5.1 Desktop GIS .................................................................................. 17 5.2 Mobile GIS .................................................................................... 18 5.3 Server GIS ..................................................................................... 18 5.4 Developer GIS ............................................................................... 18 5.5 GIS Thin Client ............................................................................ 19 5.6 GIS Services .................................................................................. 19 5.7 Database Gateway ......................................................................... 19

Chapter 6: GIS Data and Map Projections ........................................ 20 6.1 Using geographic data ................................................................... 20 6.2 Projections and coordinate systems .............................................. 20 6.3 Map projection .............................................................................. 20 6.4 Coordinate system ......................................................................... 22 6.5 Classifying attribute data ............................................................. 22 6.6 Nominal data ................................................................................. 22 6.7 Ordinal data .................................................................................. 22 6.8 Count data ..................................................................................... 23 6.9 Ratio data ..................................................................................... 23

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6.10 Continuous and discontinuous data ........................................... 24 6.11 What is metadata? ....................................................................... 24 6.12 Why is metadata important? ....................................................... 25 6.13 Why is data important? ............................................................... 25

Chapter 7: Data Format and Data Model ........................................... 27 7.1 Vector data model ......................................................................... 27 7.2 Raster data model ......................................................................... 27

Chapter 8: Choosing the Right Data .................................................... 29 8.1 What are the data for? ................................................................... 29 8.2 What is the required data resolution? ........................................... 30 8.3 What fields do these data need? .................................................... 30 8.4 Data to what extent? ..................................................................... 30 8.5 What is the scale of data survey/collection area? ......................... 30 8.6 Data have to be the newest? .......................................................... 30 8.7 What is the efficiency of your hardware? ..................................... 30 8.8 What is the GIS software used? .................................................... 31 8.9 The largest possible connection? Time allocation? ...................... 31 8.10 When do you need data? ............................................................. 31 8.11 Does data have to be updated regularly? How long? .................. 31 8.12 Data production ........................................................................... 31 8.13 Do GIS projects start as demonstration projects then gradually

expand, or do they have to be finished all at once? .................... 32 8.14 Legal data usage ......................................................................... 32

Chapter 9: GIS Technical Standards – Open GIS Consortium (OGC) ................................................................................................ 33

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owners.

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Chapter 1: What’s GIS? The full name for GIS is Geographic Information System. GIS uses absolute coordinates to

integrate spatial phenomena and by using data of different sources, GIS allows viewers to

understand spatial phenomena more easily. If we want to found out certain information on GIS,

we can use conditional queries to find the required data. For instance, to find a better location

for stores and use buffers to analyze geologic hazards or the spread of contagious diseases.

From the perspective of a map, GIS also implies “drawing maps using computers”. GIS

combines the “where” and “what” of data together. The most distinctive difference between

GIS and traditional maps is that GIS has interactive display and querying functions, since it

connects the contents of different layers.

When a topology map is displayed, you can see different surficial information, such as place

names, roads, schools, rivers, railroads and districts, and maps display these phenomena or

objects on the surface by different symbols. Therefore, maps may have many types of colors

or shapes of points or lines, such as a triangle used for a mountain peak, a point for a city, and

a blue polygon for a dam. GIS displays the information in digital formats instead of the

traditional paper maps. GIS uses many coordinate points to form points, lines and polygons, to

represent city locations, road maps or cadastral maps. Digital maps also use points to

represent information such as cities, use lines to represent roads, and polygons to represent

lakes.

The digitized database can be displayed and queried differently according to the person

using it. If we have the coordinate information, computers can quickly calculate the location of

stores, the length of rivers, or the area of schools. On paper maps, this information often have

to be interpreted by the naked eye or calculated repeatedly by equipments, such as a

planimeter. This is also one of the differences in usage between GIS and traditional maps.

The data stored by GIS is recorded in individual layers. For instance, a point feature is used

to represent a gas station or a restaurant, a line feature is used to represent a road, and a

polygon feature is used to represent the area of a park. You can use GIS hide/show layer

function, in accordance with visible scales and symbol configurations, to choose the

information to be displayed on a map.

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Figure 1. The map shows the roads in Taipei City. The area shaded in blue is Keelung River, whereas

highways are shown in lines. A few camera icons are displayed on top of the roads, which represent the

surveillance cameras that are along the roadsides.

Source:Taipei City ATIS Web http://its.taipei.gov.tw/atis/

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Chapter 2: Why GIS? 2.1 Enhance the value of geographic information The advantage of applying GIS technologies is that the digital data that GIS uses, such as

climate, address or digital maps, can be used repeatedly for various domains, including water

pipe management, disease control, mining site survey, agricultural land usage, precipitation

distribution, and vehicle monitoring applications. GIS uses a common background map as a

description and display of spatial location. With minor adjustments and the addition of thematic

layers for each project, such as a vehicle monitoring project, managers can find out directly on

the map the current location of each vehicle and their routes. Through modern communication

technologies and the integration of GPRS or 3G, system services can be developed with much

more additional values. The geographic database that is used by GIS has evolved from the

usual desktop to the Internet, allowing data to be spread among the web, thus increasing the

communication skills of geographic information.

2.2 More precise decisions GIS, being a decision support system, can communicate more direct spatial information.

Even though we are used to making marks, planning and adding notes on the traditional paper

maps, paper maps cannot precisely and reasonably overlap maps of different themes. For

decision makers, the precise spatial query, analysis and display capabilities of GIS provide a

supportive tool for different thinking.

Using wind power plants site selection as an example, GIS can be used to find out where

are the best locations for wind power plants. Away from urban area, constant strong winds,

large land mass, and away from geologic faults may all be criteria for such a location. By

inputting these conditions into the relevant layers, the best location for the power plant then

can be outputted as numeric maps after calculations. During the evaluation of site selection,

these results can also be exported as maps for discussion. Decision makers can perform

reasonable conditional decisions based on the explicit analysis results. GIS allows the results

to be exported, therefore the analysis of different schemes can be exported during the process

of decision-making, shortening the time for redrawing and labeling.

2.3 Producing maps Maps can be produced by hand-drawing, printing or GIS and plotter. Layer symbols and

map design can be done on GIS first. Configuring the numeric data of layers on GIS can save

the redrawing time for hand-drawn maps and the plate-making time for printed maps. Existing

printed maps, such as 1:5000 topology maps or 1:50,000 maps can also be scanned, rectified

and digitized to become part of the GIS database.

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Figure 2. GIS uses maps to display and query results, which is relatively similar to other designing

software. We often use GIS and designing software together. Basic maps are exported from GIS and

then detailed visualization designs are then added using designing software.

During GIS manipulation, the map scale is changed automatically when the user zooms in or

out. This saves the time for calculating the scale and the number of editors needed when maps

are made. GIS can produce maps of different scales on the screen and can also have these

maps exported as plane maps. When editing, the editor can change the symbol according to

the map theme. Under the environment of computer information, the same map data can be

produced as infinitely many map products by changing its scale, visibility or symbol.

The cartographic capabilities of GIS also are reminders for us of the difference between GIS

geographic information and other pure text data tables – shape information. When we see

different points or lines on maps, we are using our right brain to visually process and

comprehend information; however, with the text or numeric data provided by the databases,

we are using our left brain to logically cognize information. The right brain is mainly used for

processing direct and graphic information. In collaboration with the GIS database, querying

results displayed directly as maps, the visual effect will mean much more than words.

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Figure 3. GIS uses maps to display thematic information. Topology will usually be displayed as 3D or the

so-called 2.5D for more realistic surficial representations.

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Chapter 3: What is GIS Used For? 3.1 Where are the locations?

GIS can help us locate the target we are looking for, such as the closest gas station.

Finding the location of the target is one of the basic functions of GIS. GIS can usually help us

perform the following two types of queries:

1. Spatial query (find texts by map): select targets on the map and find the data for these

targets.

2. Attribute query (find map by texts): set filter conditions and let GIS find targets that

match these conditions. Location can be shown by a change of display color.

Figure 4. GIS can precisely calculate the restricted area coverage of an airport within seconds. All you

need is the center and radius and the area can be calculated, helping managers to estimate the cost and

come up with monitoring plans.

3.2 Visualized display of numbers Numeric data with spatial information can use maps to emphasize spatial relationships by

using bar or pie charts to label the location of the maximum or minimum value. Through the

background display of maps, the geographic location of numbers can be displayed subjectively

and the information displayed can be changed at anytime.

For instance, a toy company not only need to use GIS to help them know what other

competitions are near their stores, they also need to know the distribution of younger kids,

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household income, and so forth. Hygiene units use GIS to keep control of hospitals and clinics

and analyze the statistics of medical qualities, such as the acceptable medical quality provided

for each unit population. On maps, these data requires the support of social-economical

database and also statistic data from different hospitals and clinics to understand what areas

are medically insufficient or overabundant.

Figure 5. Use GIS to illustrate the spatial distribution of contagious diseases. 2005 Taipei City Syphilis

and HIV statistical graph, Center for Disease Control of Taipei City.

3.3 Density maps Displaying statistical data on normal maps is complicated, especially when data relevant to

district size is present, such as population density or the green land allotted per person in

urban area. When using GIS spatial query and thematic map functions, the places with highest

population density or limited green land resources all requires area as a standardization

reference. Census requires area of different administrative levels, such as villages or counties,

whereas green lands require the area of each park. After mathematical calculations, the theme

displayed on a map can become something that is comparative.

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Figure 6. Population density of Taipei City

Standardization is a very important part of data pre-processing when comparing data. The

area of a land mass can directly influence the display of density data. Census statistics cannot

directly show the density differences between different areas. Since GIS data uses

coordinates as foundations, no matter politic boundaries or green land layer, the area

population and green land allotted per unit can be obtained after area calculation. Computer

displays various colors to inform the users of the numeric highs and lows; therefore, without

much thought, most people will direct their eye focus to areas shaded in darker or

eye-catching colors, then to other lighter colors. A problem is recognized or solved during this

visual capture.

3.4 Buffer analysis GIS can be used to define exact spatial extent and assist in the spatial extent planning of

management. For instance, bird-breeding prohibited zone around an airport, internet café

prohibited zone around schools, emergency zone of a nuclear plant, and so forth. GIS not only

illustrates the controlled zone but also is used to find out the management unit within the zone.

Under the cross-analysis of GIS layer structure, the speed and accuracy of relevant

management works can be increased.

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Figure 7. Map shows the schools and roads within different distances of the nuclear power plant. When

the wind affects the flow of radioactive dusts, management and control actions will be taken according to

the schools in different wind directions.

Figure 8. Route planning is an application of GIS that solves distance problems. Different stops can be

appointed, and according to the sequence of each stop, the best route can be found to reduce traveling

cost.

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3.5 Time changes GIS represents the phenomena of a point in time. If we place the phenomena of different

time periods within the same location, we can show the phenomena in a time span. Using the

changes in the past to perform estimation and determine the path of an action, such as the

spread of contagious diseases or the path of a typhoon.

1. Through a map of the typhoon path, we can understand the seasonal typhoons more

clearly. For instance, if the Central Weather Bureau records the path of a typhoon, its

direction and possible influential zone can be estimated and forecasted.

2. Crime location change with time allows the cops to know where to monitor and patrol.

This scenario uses cases that have already happened to prevent future possibilities.

3. The historical tracks of vehicle GPS data allows the manager to know which section of

the road is always jammed. By controlling the vehicle speed, fuel and time can be

reduced. Historical tracks of vehicles also can be used as a reference for the evaluation

of drivers’ driving behaviours and performances.

Figure 9. The map shows the path of the typhoon across the western Pacific Ocean. The counties with

yellow boundaries represent the area affected by this particular typhoon.

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Chapter 4: Performing GIS Analysis 4.1 Problem design A GIS analysis usually starts from clarifying the content of a question:

Where did cases of Dengue Fever appear last week?

How many hydrographic stations are within each watershed?

Which factories are within 300 m of schools?

These questions have to be as detailed as possible, especially the portion that describes

space. This can help you to decide an analysis method to obtain the final result.

Figure 10. The figure shows areas along a flight path that are affected by aircraft noise. Deep blue are

the areas of greatest effect. Through a figure like this, we can easily tell which villages are affected the

most.

4.2 Data collection The data and feature type you use will decide what kind of analysis method you should use

to approach your question. In other words, if you need to use an alternative method to obtain a

result, then you have to search for data sources that can help you get your answer.

Data can have many sources, such as the internal database of management units,

databases from other units, existing vector CAD files, the Internet, private commercial

companies, government agencies, and so forth.

The design of your question and your budget will decide what kind of data you can get and

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what kind of data you can use. Some analysis requires high precision data, such as aerial

photographs with precision of centimeters or 5 m digital elevation models.

Figure 11.The above figure illustrates the analytic result of cash truck routes. The utilized data includes

location of banks, metro system, highways and express-ways, main roads, and rivers.

4.3 Evaluating analysis methods The details of the problem to be solve and how to go-about this problem decides the

analysis method that should be used.

For instance, if you only want to know a brief idea of the break-in robberies of a particular

city, then you only need to display all the individual cases on the map. However, if this

information is going to be used as evidences for trials, then you would want to provide the

location and number of crimes within a predetermined period of time by performing a more

thorough analysis.

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Figure 12. The figure uses GIS to display the individual robberies within a city, which can be used to

estimate the entire city. Red represents areas of high criminal density whereas blue represents the

opposite.

4.4 Processing data After deciding the analysis methods, the next step would be to process and handle your data

according to the original question.

For example, if the question is to see the location of all branch offices on the map, then you

will need coordinate information such as X and Y. At times you may only have address

information; if this is so, this information will have to be converted and confirmed of its correct

coordinates. Names, managers and other attributes will also have to be keyed-into the

computer.

To display quantity data, such as the number of parking lots within an area, you will need to

use classification methods to divide the numbers into classes and set each class in a different

color. It is then will the computer know what color to represent what classes in.

If you want to inquire how many gas stations are within an area, then you might need to

relate the information of different layers or display them together in a layer.

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Figure 13. The figure is a travel map of Kenting National Park in Taiwan. The figure shows scenic spots,

roads and gas stations. The decision of displayed contents will depend on the final map user and

purpose.

4.5 Exporting results The last step of GIS is to export your analysis results. According to the processed analysis

results, you can make decisions or further explain the exported results.

The results can be displayed directly on the computer screen or be printed out as paper

maps. Tables and statistical graphs can also be made. Most GIS have add-on standard

graphic functions,

providing

interfaces and

tools for users to

flexibly design

simple thematic

analysis result

layouts.

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Chapter 5: GIS Software GIS software provides functions for users to key-in, save, analyze and export geographic

spatial information. The main functions of GIS include:

Input and manipulation of spatial information of different types, such as store

addresses, village and town boundaries and other geographic information.

Database management (relational database architecture).

Analyze and inquire spatial information.

Draw, edit and print out maps.

Easy-to-operate graphic user interface (GUI)

Figure 14. GUI of SuperGIS by SuperGeo Technologies Inc

GIS is the software that can process basic data and display them, and is also the

professional software that can perform more complicated environmental protection

management and research analysis.

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Since the beginning of the development of GIS industry, each year has been a steady

growth. In the recent years, GIS applications have not only broadened but also in the same

time, the spatial information industry, biochemical technology and nano technology has

become the three most important newly-evolved industries, as listed by the U.S. Bureau of

Labor Statistics. The following will list the global GIS software development trend and will take

SuperGIS as an example.

5.1 Desktop GIS Input of geographic data, including image rectification, digitization, processing and other

tasks, have to be performed on the computer. Processed and analyzed results will be

produced as images or exported and printed out on a printer. Required analysis will depend on

the question raised, and different tools will be used to process the particular problem, such as

network analyst or raster spatial data analyst.

The name “Desktop GIS” emphasizes the operational platform and suitable GIS

environment. For instance, SuperGIS is a Desktop GIS that processes most of the input,

image rectification, data digitization and editing, question analysis, attribute data editing and

export of results for geographic information. If the analysis question requires special methods,

then extension modules are required for such process. Network analyst is used to resolve

route planning and service area problems, whereas spatial analyst is used to perform

interpolation and other related algorithm for raster data. The main functions of GIS and other

extensions are all aimed to resolve and analyze problems.

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5.2 Mobile GIS Using Global Positioning System (GPS) with GIS to perform field surveys, the spatial

accuracy of the surveyed data can be greatly increased. During survey procedures in the past,

GPS can only output the coordinates of the current position. The positioned coordinate values

must be transferred to GIS database before it can become GIS data.

Mobile GIS is mainly used to input the positioned GPS coordinate points directly into GIS

system. Users can prepare data layers of the surveying area before heading out into the fields,

such as the cadastral data or forest boundaries. These data can be inputted into the computer

prior to field surveys. The computer used for field surveys are usually PDA or tablet PC, which

are lighter to carry around in the fields.

For example, SuperPad can be integrated with any GPS devices. Drawing the GPS

coordinate position on the map, we can use such information to add the spatial information of a

new point, line or polygon. In combination with survey forms designed for different themes,

such as forest survey or water resource survey, attributes can be inputted directly on the spot.

After a survey, the data is already in GIS format, and can be transferred to desktop for further

analysis.

5.3 Server GIS Under the information environment of the World Wide Web, many GIS functions can be put

up on to the Internet. Servers are the hardware or the service body that provides information

services. In a GIS project, we need a simple way for everyone to search online and publish

data, and in this case we will need a GIS server. For example, the geographic information

query provided by the Ministry of Interior and the GIS services provided by the Taipei City

Transportation Information System, have been set up using this kind of software platform.

For instance, a map service established by SuperWebGIS will automatically send the query

action of the user to the server, whether it is a zoom-in or record query. The server will then

find the matching data and draw the result on the map. General users will not directly obtain

the original GIS data, but rather the predefined layer display results. Users usually cannot

obtain the source data either, because these data require special software, such as SuperGIS

or SuperViewer to view. The function of Server GIS is to collaborate with the system function

of specific query-display services. Querying the number of field survey samples within a study

area and transportation information service, which displays the traffic condition of road sections on the map, are a couple examples of such service. 5.4 Developer GIS In specific GIS projects, many GIS systems lack integration system functions. For the

requirement of these specific projects, they may need direct and existing databases, such as

customer information, cadastral database and so forth, to perform information integration.

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When the existing database system is going to be integrated with GIS system or giving GIS

display and query functions to the existing system, developing components will be needed for

development.

For instance, SuperObjects can combine the GIS vector and raster database displaying

functions and allow the GIS database to achieve the purpose of displaying and querying data.

Under the developing environment, the original exterior database system can also be

integrated to develop a system with specific functions.

5.5 GIS thin client GIS as a web service or information has already become a current trend. Ever since Google

Earth was released, using services and owning data does not need to be saved or designed

on a single machine. A simple GIS system, such as SuperGIS Explorer, can directly obtain

data or use GIS functions through the Internet. Users do not have to prepare data or develop

their own applications anymore. The functions provided by GIS will be defined and prepared

by the GIS services.

5.6 GIS services The purpose of GIS services is to publish GIS functions and data through the Internet. Users

need a simple program or a data transfer protocol format commonly used on the Internet, such

as XML, to obtain the functions of GIS services.

For example, SuperGIS Web Services provides GIS online analysis and data services,

which can be used as references for the application data and functions of development

projects in site selection, transportation monitoring or environmental survey. Advanced GIS

services can not only lessen the cost of buying data and system function development but also

keep the data at its newest.

5.7 Database gateway Database Gateway is used to resolve the problem of GIS when managing large databases,

allow queries and write-in actions to be done under an environment with many users, and also

provide a single exterior connection for the actual database. It is used as a software interface

between the relational database and the GIS system. When multiple users are using the same

database, this kind of software is required to process the issues that occur during

simultaneous write-in of data.

The recorded contents of GIS data files are composed of shapes, attributes and the

connection between the two. File types include vector, raster and numeric data. Therefore, it

needs a portal for it to communicate with other GIS application interfaces, such as the

SuperGIS GDE, which can inherit the commonly-used relational database and data

management functions, such as creating, updating, and deleting database.

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Chapter 6: GIS Data and Map Projections

6.1 Using geographic data In GIS system, environmental information and social-economical data can be separated into

different themes and co-related layers. A layer is a collection of the same type of objects, such

as buildings, schools, lakes or geological areas.

These data may contain definite spatial information, such as latitude and longitude

coordinates or recordings of some reference points (e.g. address, district area, nearby

reference landmark, cross-section roads, gas station code or river name).

During the task of processing geographic data, GIS systems require definite spatial

information. GIS can convert uncertain spatial descriptions into specific X and Y coordinates

through geocoding (positioning addresses) and displaying the coordinates on the map.

6.2 Projections and coordinate systems All geographic data must have the same coordinate system for them to overlay correctly and

be enabled of calculation between layers. In other words, layers of different coordinate

systems must be adjusted to the same map projection and coordinate systems.

6.3 Map projection Map projection is a mathematical process of converting location information on the Earth to

planar maps. All map projections have distortion to a different degree, which affects the actual

shape, area, distance or direction of the original object on the Earth.

This is why some countries will have extremely exaggerated shapes, such as the size of

Greenland on the world map looking as big as the entire North America.

Many issues have to be considered when selecting the appropriate map projection and

coordinate system, including the location of the geographic data being recorded (high-latitude

or low-latitude?), how large is the area being projected, and whether the actual length or area

should be preserved.

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Figure 15. Map of Asia produced using Albers projection.

If the extent of the geographic data you are processing is as small as a town or village, the

distortion of the geographic surface can often be disregarded. However, as the extent of your

geographic data grows (e.g. Asia or South America), the distortions caused by the projection

method you choose will be very obvious.

Figure 16. World map shown in Mercator projection. Notice how large Antarctica looks in this projection.

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6.4 Coordinate system Coordinate system defines the origin and units used by all elements in the 2D dimension.

Latitude and longitude is also a coordinate system, called Geographic Coordinate System. If

the original GIS data is a collection of data from different sources and/or processes, then the

coordinate system and projection of the data needs to be confirmed.

6.5 Classifying attribute data Any geographic data will have one or more attributes to record the details of this record of

data, including text descriptions or numeric data of the measurement or survey results. GIS

display and classification will be controlled by the type of these attribute data. Attribute data

types include:

Nominal

Ordinal

Count

Ratio

6.6 Nominal data Nominal data distinguishes the contents of different records of data. It can aid in organizing

and processing the difference between data. GIS have specific display methods for the

classification of this kind of data, and unique symbol is the most commonly seen method.

For instance, road data records the road class of each road. In GIS, classification of roads

can be done using the road classes of highway, expressway, alley and so forth. For points,

classification can be done using the classes of school, government, restaurants, and so on.

The attribute properties can be represented as a numeric code or described in texts. To limit

the space in the attribute table required for saving this information, longer text strings are often

represented as codes.

6.7 Ordinal data Ordinal data can distinguish data value by arranging them from high to low, for instance,

river class (class 1, class 2, etc.) or land-use potential (low, medium and high potential). This

can be done by using 1, 2, 3 …, N to record the class property.

Ordinal data can only tell you the ranking and order; you cannot know which value is larger

or smaller than another by how much. For example, if a database records the rank of cities, in

which Taipei is ranked as urban-city and Lodong as a town, we can know from this rank that

Taipei is bigger than Lodong (in terms of population), but we do not know the exact difference.

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Figure 17. This map shows the condition of water pollution in Northern Taiwan. Blue, yellow and red

represents areas of low, medium and heavy pollution, respectively.

GIS can use the rank or class to classify data. For instance, the land-use potential of an area

can be classified accordingly for users to see the map and understand which areas are of high

land-use potential.

6.8 Count data Data that can be counted are considered count data. This type of attribute data records

actual numbers, such as the population, number of motorbikes, number of households,

number of married couples, and so on.

6.9 Ratio data Ratio data is obtained by dividing the count data of a field by another. For example, dividing

the population by the area will be the population density. By using this ratio, we can

standardize the count. At times, absolute count data cannot explain the geographic

phenomena fully. If district A has recorded 50 people with flu while district B only has 5,

“quantitatively” it would seem like there are more people with flu in district A; however, if the

total population of district A is 10,000 while district B is 100, the ratio of getting a flu in district A

is 0.005 and in district B is 0.05. By looking at the ratio of flu infection, it seems that the flu in

district B is much more serious.

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Figure 18. The above figure illustrates the population density of Taipei City and Taipei County. The

darker the red means the denser the population. In areas of dense population, there are usually more

villages and such villages usually have smaller sizes compared to the villages in areas of lower

population density.

6.10 Continuous and discontinuous data Nominal and ordinal data are discontinuous data, for it records a fixed number or code and

many records have the repeating attribute.

Count and ratio are continuous values, where each value can be integers (e.g. 134) or

decimals (e.g. 3.1434). To be sure of how to classify data, you can first find out the maximum

and minimum values to help you understand the distribution of data.

6.11 What is metadata? Metadata is often defined as “the data of the data”. Metadata provides additional information

for the data, which includes some of the information necessary for using the dataset. Metadata

describes the background and source of the data, but this usually does not include the data

itself. Metadata would include:

Time the data was created

Field names and types

Keywords

Data quality description

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Data production unit and method of production

Data structure and security level

6.12 Why is metadata important? Metadata is very important, because it can not only describe what the data is but also

decrease error in data reading and usage.

Geographic data is required to keep up to GIS software and business standards. Data that

conforms to GIS software data standard can be used with much more ease and can be

exchanged in different application systems and platforms. Through building of metadata, you

can standardize the naming, definition, coding and manipulation of a project between different

departments. This task produces an operational mechanism for communication, data

standardization and data sharing.

Metadata provides a reference for data users, such as “how do I plan my data layers”.

Metadata tells you what data can be used, where the data is, what the production date is, what

the data format is, and what kind of security level is set. For professional GIS managers,

metadata provides the reference for the creation, management and updating of spatial and

attribute data. This way, data update can be done more effectively and other data of the same

type can be integrated into the database. Metadata is not the production result but rather a

reference source for increasing the application of spatial data. It helps you to gain more

efficiency during your GIS analysis and reading.

6.13 Why is data important? In order to use GIS to draw maps, you need good quality data. For instance, if you want to

know the current position of your car, you need detailed road data as the background map. For

the car to be shown at the exact position on the map, you need to make sure that your road

data is the most detailed and up-to-date.

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Figure 19. GIS showing city and topology data on actual surface

Figure 20. Combined query in GIS, integrating graphs, tables and pictures

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Chapter 7: Data Formats and Data Models

GIS has three fundamental data formats.

Spatial data – used to constructs the basic map

Spatial data is made up of points, lines and polygons, which are considered as

fundamental GIS objects. Spatial data are used to describe the location and shapes

of physical objects, such as the shape of lakes, roads and cities.

Tabular data – provides data description

Attribute data are used to describe spatial information, such as the location of a

house. The map can connect to the house’s pictures or information on nearby

environment and facilities.

Image data – used for image display and analysis

Image data has many different sources, for instance, satellite images, aerial

photographs or scanned maps (scan paper maps to obtain digitized image files).

Other than the data formats, there are two main data models in GIS.

7.1 Vector data model Discontinuous objects, such as the location of convenient stores or watershed area. Data

are often described in vector formats (points, lines and polygons).

7.2 Raster data model Each raster grid will contain a value. Digital Elevation Model (DEM), for example, will have

the height value contained and saved in each grid. Other data such as temperature or satellite

images will often be created using raster formats.

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Figure 21. This map shows the 3D simulation of a vector layer (road) overlaid on top of raster data

(satellite image).

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Chapter 8: Choosing the Right Data When you are in the process of planning a GIS application system, you will have to decide

on what kind of data you will use. List your requirements and evaluate the dataset you will use

accordingly. The following are some questions that you may need to consider when figuring

out what kind of data you require.

8.1 What are the data for? Is the data from a GIS database used to export a thematic map? Or is it used to complete a

problem analysis with a specific goal? Should the restaurant information be positioned on top

of a road map? Or do you only want to export a map to locate source of pollution and the

factory? Or do you want to use GIS software to develop a vehicle monitoring system?

You need to answer these questions thoroughly prior to building your GIS applications,

because some of the following GIS applications will have to consider the answer to this

question. You not only have to fulfill a recent goal but you also have to fulfill the functions that

you need.

Figure 22. Topology map and GIS vector data integrated in one coordinate system.

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8.2 What is the required data resolution? To utilize the GIS system more effectively, you need to confirm the resolution of your data.

For instance, do you need detailed 1:5000 road data? Or do you need 1:25000 highway data?

Some road data comes in double-line or single-line, so does the system need network analysis

functions? Or is it simply for map display? Network analysis requires complete road-center line

data, whereas a map only displaying the road outline may use double-line road data that is

without topology information.

8.3 What fields do these data need? Using important landmarks as an example, should the fields in the landmark be classified

and displayed by name? This will be decided regarding to the requirement of your application

system. The classes of the landmark data may include transportation, restaurant, survey,

education and culture, and so on. Landmark names may include C.K.S. Memorial Hall, Taipei

Main Station and other commonly used names. The data in these fields may have already

been surveyed by surveyors, which means that some data only exist after a round of surveying

tasks (e.g. the number of waitresses in a restaurant).

8.4 Data to what extent? If the system needs to process census data, the extent may be as small as town/village

boundaries or as large as Asian country district boundaries. For the data extent in GIS projects,

you need to be sure of the data boundaries you need. If your data is a combination of different

scales, you also need to pay attention to the relationship between each scale and the data

resolution.

8.5 What is the scale of data survey/collection area? In the process of building a GIS project, what should the scale of the system study area be?

If the system is intended to display the income of social families within a city, then you will

need districts smaller than that for the system to be meaningful. Data of smaller districts can

be integrated into larger districts. Take the income data of families in the 12 districts of Taipei

City as an example, if we calculate the entire Taipei City, then we will not be able to see any

spatial differentiations.

8.6 Data has to be the newest? In some GIS applications, timeliness is one of the most important factors that need to be

considered for data, for example, using satellite images or aerial photographs to perform the

analysis and evaluation of post-disaster recovery. This kind of task requires the immediate

images after a natural disaster, not images of five years prior to the disaster when the land

surface has not yet been harmed. Relatively, if this project is using images only as a

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background reference, then it will only need recent images without cloud-cover.

8.7 What is the efficiency of your hardware? Confirm the hardware of your workstation. Is the operating system Windows XP, Windows

Vista, Macintosh or UNIX? Can you work offline or do you need the Internet? Or maybe you

need to be able to work in both environments?

8.8 What is the GIS software used? The file formats used by the GIS software will influence the type of formats you can select

and buy as your data. For instance, SuperGIS uses Geo files and can also support Tiff images.

8.9 The largest possible connection? Time allocation? The maximum allowed connections within a unit will decide the system’s performance. As

for a public system, it is usually rare to achieve the maximum allowable connection at a time.

Part of the system, within a particular period of time, may have high usage demand, for

instance, the public may want to know the traffic condition of highways before going to work

and this may cause a usage peak for the query function on the system. Or, if it is a GIS

educational application system, the usage rate may be relatively low during winter and

summer holidays.

8.10 When do you need data? Most of the basic data can be used once bought, for example, landmarks, roads or river

maps. Contrarily, if it is data that cannot be obtained through application or other projects, the

data will have to be collected before hand. The time required to complete a first-hand database

as this will depend on the funding, workers and processing method available and used. This

will of course be more time costing. The required time may be weeks, years or even up to

decades. After data collection, there is also the time required for checking and data

post-processing; therefore, at times, processing first-hand data is also included in the content

of a GIS project.

8.11 Data has to be updated regularly? How long? You have to be sure of which dataset needs to be updated. Most data providers will have

many different ways of updating their data, and different data will require different renewal

requirements. For instance, in a monitoring system, the location of the vehicles may have to be

updated once per 15 seconds, whereas the road map or aerial photographs that are used as

backgrounds can be updated on a half year basis. The method for update includes complete

and partial updates. It is better to clearly state the data update requirements within a project

contract.

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8.12 Data production GIS can use data produced by one company or by different companies. Therefore, under

the circumstances of having to use data of different production backgrounds, it is very

important to unify a set of coordinate system for the system to overlay data correctly. Data

coordinate systems may include latitude and longitude (WGS 1984), cadastral coordinates,

TWD 1967 or TWD 1997 Transverse Mercator. Some coordinate transformation may have to

be done on the dataset for them to be unified.

If your dataset is large in quantity (such as the survey data of the entire nation), you should

probably test and come up with a surveying method within a small study area before you

actually go out and perform the actual field survey. This way, you will be able to find out the

blind-spots of data quality and will be able to test the accuracy between different datasets.

8.13 Do GIS projects start as demonstration projects then gradually expand or do they have to be finished all at once? According to the experiences of past projects, many projects start with a small

demonstration plan, which establishes a database of a smaller study area, to test the

functionalities of the system and then broaden to a larger scale project. This may start from a

town or city, then to the whole country. The plans within this entire project may be cut up into

short, medium and long term goals. When coming-up with a project plan, you will also need

information and reference on the cost of data provider and content of the project service.

When and how are important when planning a GIS project. If a GIS project is only done once,

the chance for its maintenance and expansion will be slight. However, an efficient GIS project

may also turn out to be a good sample project for demonstration and be expanded upwards.

8.14 Legal data usage Paper maps or other published contents exported by GIS are all considered to be part of

data usage rights. Between data providers and data users, the allowable usage and illegal

data usage should all be discussed and listed within in the contract. The data usage rights in

an internal network and public network all have to be authorized by the data providers. Most

GIS data are files that can be easily copied and passed around. In usual usage right

declarations, you will be prohibited to pass and transfer data to unauthorized units without the

authorization of the data provider. The data provider should provide the limitations of the data

usage, authority and other conditions that should be noted within the purchase contract. Data

usage units should also be aware that the data is protected by copy rights and intellectual

property rights. When using these data, you have to be aware of the common practices of the

law.

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Chapter 9: GIS Technical Standards – Open GIS

Consortium (OGC)

OGC is the abbreviation for Open GIS Consortium. In 1994, industries, government

agencies and the academic around the world in the GIS domain founded a globally common

geographic information standard for the exchange of data, called OGC.

In the past, because GIS doesn’t have a common standard, the GIS data and technologies

of different units (whether interiorly or exteriorly) could not be integrated at ease. Also, GIS and

other existing systems could not be integrated either. At the user-end, data will have to be

converted to be read on different GIS platforms, where at times, some of the data formats were

not even supported. Therefore, the maintenance, update, key-in, and resource sharing of GIS

data will often cost relatively great effort and time.

As of now, OGC has over 388 members (up to January, 2007), whose tasks are to develop

interface specifications that can be obtained by the public domain. The standard developed by

the organization supports interoperable solutions on the Internet and wireless communications,

Location-Based Services (LBS) and mainstream information technology. These allow the

technological development of GIS to be applied in different fields, producing more delicate

spatial information and services.

Visit OGC at: http://www.opengeospatial.org