GISdevelopment.net --> Proceedings --> GISDECO --> 2004
An Interactive Digital Guide Map of Dhaka City
Meher Nigar Neema
Department of Urban and Regional Planning
BUET,Dhaka
Farhana Ahmed
Department of Urban and Regional Planning
BUET,Dhaka
Farzana Akhter
Department of Urban and Regional Planning
BUET,Dhaka
K. M. Maniruzzaman
Department of Urban and Regional Planning
BUET,Dhaka
Abstract
This paper describes the development of a GIS-based interactive map. Preparation of a GIS-based IMDC (Interactive Map of Dhaka City) incorporated with two new functions - one to search a specific named feature with automated map extent updates to maximize the display of target feature and the other to activate hotlinks to graphics and text descriptions of features - is presented. At first a digital map was prepared from a paper base map. Then the map was integrated with a graphical user-friendly interface consisting of different buttons, tools and documents. The developed functions were associated with new button and tool. PC ARC/INFO and ArcView were used as the basic GIS software because of their wide availability and use. By applying the first function the user can easily locate any feature on the interactive map. The second function will help the user view images and information associated with a specific feature. The interactive map promises wide range of use in diverse applications and provides numerous options to produce productive results.
Introduction
A map is a graphic representation of all or part of the earth surface on which cultural and natural features are depicted by symbols, drawn on a two-dimensional plane. Maps are an effective way of presenting a great deal of information about objects and the spatial relationship of objects (Star and Estes, 1990, p. 175). Maps are used for a wide variety of applications. Sometimes it acts as a decision making tool, sometimes a communication tool, sometimes an analytical tool and so on. By thinking and working geographically, professionals in every field have discovered the advantage of using maps for decision support (Pictographics, no date). They have always sought tools to enhance their analytical, problem solving and decision making capability. One of the most common and basic items in the spatial workers’ toolbox has been maps. Many professionals including geographers, architects, and planners, have been using maps from for many purposes. Whether siting a business, finding a location of a community service or figuring out the best route through traffic, maps are pioneers in applying techniques to cultural resource management.
Maps are also used by non-professionals in everyday life. Traditionally, maps have been drawn on paper or similar media. In paper maps, the data storage and data display functions are combined. Paper maps store and display information in the same map sheet (Anonymous, no date). Paper maps, however, have certain limitations that do not apply to digital maps, the use of which is flourishing due to the proliferation of computers.
Geographic Information System (GIS) technology has given us the capability to use digital maps in a variety of ways. We can get more than just maps – all kinds of information about the local area, from points of interest to the availability of goods and services, can be part of the mapped information. In a sense, a map can be a live extension into the immediate environment, feeding us information that’s organized spatially and searchable by whatever we want to know (Pfister et al., 2001, p. 43).
Computing technologies are becoming more portable, easier to use, better connected and less expensive, all of which contribute to the growing expansion of GIS into consumer markets (Pfister et al., 2001, p. 43). Digital maps, created by GIS software can now be served through websites, giving users complex, interactive maps. Internet mapping is a powerful communication tool. With easy-to-use Web browsers, digital maps on the internet provide a much more dynamic tool than a static map display. Web-enabled GIS-based map lets one deliver interactive query capabilities such as (Pictographics, no date):
To accomplish the goal of providing user-friendly public access to the geodetic control network databases, descriptions and photos, an interactive map using GIS data and ESRI’s ArcInfo and ArcView software has been developed. In this study, an IMDC (Interactive Map of Dhaka City) was prepared showing a variety of features. With an interactive map, the user can specify the kind of display of the map he prefers or the kind of analysis or query he would like to perform with the stored data through the use of a Graphic User Interface (GUI). The display of the map would change and the results of analysis would be shown on the fly. The exercise provided insights and skills that would be required if the study is carried out further to include more powerful planning routines.
The project developed is a preliminary instance of such work in the field of GIS. It is hoped that this study will provide a base for more detailed and comprehensive research in future and act as a useful guide to create other such applications.
Base digital map of Dhaka City
A copy of the Dhaka Guide Map was collected from the Survey of Bangladesh. The scale of the map is 1/20,000 or 5 cm to a kilometer. The following features were digitized:
Table 1: List of Different features of Dhaka City digitized as separate themes
The digitizing process has been carried out on-screen using scanned images of the paper base map as guides. Different features were digitized as separate themes shown in Fig. 1. After the digitization process, topology was created, errors were identified and corrected, and attribute data was added to each coverage. A number of Simple Macro Language routines were used to simplify the repetitive tasks.
Implementation of interactive functions
Avenue is the customization and development environment for ArcView. It is an object oriented scripting language that is fully integrated with ArcView. With it one can perform the following tasks (ESRI, 1996, p. 1):
The search option is used to find a particular feature in a view. It gives a list of features and makes a theme, that the user specified from a list, active in the view and finds a feature. When a feature is found, ArcView selects it and pans the view so that the feature is in the center of the view. Features highlight on the view when they are selected and remain highlighted until a different selection is made, or until they are deselected. By default, selected features highlight in yellow and zooms to the spatial extent. Search is a quick way to select a particular feature of interest.
The Hotlink tool enables the features of a view to link with different objects. Hotlink helps accessing of virtually any data or application directly from a view. For example, one might click on a building to display its floor plan, click on a land parcel to review its legal documents, or click on a country to play a video about it. A hot link is followed when a feature in a theme is clicked with the Hot Link tool. To see a feature’s images and descriptions the user has to locate that feature with the help of search function.
Incorporation of the digital map with the interactive functions
In a graphical user interface (GUI), the digital map was incorporated with the interactive functions by creating new controls and adding them to the interface. Changes were made in the ArcView's interface for view document shown in Fig. 2. Two new controls were added to the interface - a Search button and a Display tool. The scripts for searching a feature and displaying graphics and text descriptions of features were assigned to the button’s 'Click' property and the tool’s 'Apply' property respectively. These two scripts were named as View.Highlight and View.Display respectively mentioned in Appendix. These controls were defined by giving icons and help messages. The 'S' icon for search function and the 'Frame Picture Icon' for display function were selected. When the cursor is placed over a button and a tool its function is indicated by a message displayed on the status bar.
Searching a feature in a view
To search a particular feature on a view the user has to get a list of names from which he will choose an option. Then the chosen option will be highlighted in the view. The user can find a feature in the following way:
Displaying images and information
The action and the field are specified in the Hot Links panel of the Theme Properties dialog. Each theme in a view can have its own hot link definition. There is no default hot link definition. Hot links have to be defined before they can be used. Pathname of graphics and text has to be given in a specific field of the attribute table to access picture and information. If after clicking on a feature a beep sound occur it means that ArcView cannot find the application or file defined for that feature. The user can gain access to pictures and information of a particular feature in the following procedure:
Fig. 2: Customization of ArcView Interface
Fig. 3.1: Message box containing list of themes
Fig. 3.2: Message box containing list of features in the selected theme
Fig. 3.3: The associated feature is highlighted and displayed in the view
Fig. 4: Hotlink action displays the beautiful image and information of ‘National Museum’
Conclusion
The paper describes the preparation of a GIS-based interactive map of Dhaka City integrated with few extended capabilities which can be used as a guide map. ArcInfo and ArcView GIS software are used to prepare the interactive map, which includes preparation of digital map and customization of user interface. For this purpose software and hardware were used to capture, store and organize, manipulate, analyze and display spatially referenced information. The system, including its graphical user interface, was implemented with PC ARC/INFO's Simple Macro Language and ArcView's Avenue Programming Language. In this study, an attempt was made to prepare an interactive map of Dhaka City showing a variety of features. But due to constraints, only some rudimentary interactive features were included, but the exercise provided insights and skills that would be required if the study is carried out further to include more powerful planning routines. Also, this study has tremendous scope in different activities of planning and other field and can serve as a basis for future relevant research and studies.
References
Appendix
List of Avenue Scripts
1. View.Highlight
An Interactive Digital Guide Map of Dhaka City
Meher Nigar Neema
Department of Urban and Regional Planning
BUET,Dhaka
Farhana Ahmed
Department of Urban and Regional Planning
BUET,Dhaka
Farzana Akhter
Department of Urban and Regional Planning
BUET,Dhaka
K. M. Maniruzzaman
Department of Urban and Regional Planning
BUET,Dhaka
Abstract
This paper describes the development of a GIS-based interactive map. Preparation of a GIS-based IMDC (Interactive Map of Dhaka City) incorporated with two new functions - one to search a specific named feature with automated map extent updates to maximize the display of target feature and the other to activate hotlinks to graphics and text descriptions of features - is presented. At first a digital map was prepared from a paper base map. Then the map was integrated with a graphical user-friendly interface consisting of different buttons, tools and documents. The developed functions were associated with new button and tool. PC ARC/INFO and ArcView were used as the basic GIS software because of their wide availability and use. By applying the first function the user can easily locate any feature on the interactive map. The second function will help the user view images and information associated with a specific feature. The interactive map promises wide range of use in diverse applications and provides numerous options to produce productive results.
Introduction
A map is a graphic representation of all or part of the earth surface on which cultural and natural features are depicted by symbols, drawn on a two-dimensional plane. Maps are an effective way of presenting a great deal of information about objects and the spatial relationship of objects (Star and Estes, 1990, p. 175). Maps are used for a wide variety of applications. Sometimes it acts as a decision making tool, sometimes a communication tool, sometimes an analytical tool and so on. By thinking and working geographically, professionals in every field have discovered the advantage of using maps for decision support (Pictographics, no date). They have always sought tools to enhance their analytical, problem solving and decision making capability. One of the most common and basic items in the spatial workers’ toolbox has been maps. Many professionals including geographers, architects, and planners, have been using maps from for many purposes. Whether siting a business, finding a location of a community service or figuring out the best route through traffic, maps are pioneers in applying techniques to cultural resource management.
Maps are also used by non-professionals in everyday life. Traditionally, maps have been drawn on paper or similar media. In paper maps, the data storage and data display functions are combined. Paper maps store and display information in the same map sheet (Anonymous, no date). Paper maps, however, have certain limitations that do not apply to digital maps, the use of which is flourishing due to the proliferation of computers.
Geographic Information System (GIS) technology has given us the capability to use digital maps in a variety of ways. We can get more than just maps – all kinds of information about the local area, from points of interest to the availability of goods and services, can be part of the mapped information. In a sense, a map can be a live extension into the immediate environment, feeding us information that’s organized spatially and searchable by whatever we want to know (Pfister et al., 2001, p. 43).
Computing technologies are becoming more portable, easier to use, better connected and less expensive, all of which contribute to the growing expansion of GIS into consumer markets (Pfister et al., 2001, p. 43). Digital maps, created by GIS software can now be served through websites, giving users complex, interactive maps. Internet mapping is a powerful communication tool. With easy-to-use Web browsers, digital maps on the internet provide a much more dynamic tool than a static map display. Web-enabled GIS-based map lets one deliver interactive query capabilities such as (Pictographics, no date):
- Searching for specific site locations
- Displaying and viewing multiple data sets
- Conducting queries for specialized analysis
- Performing data commerce
- Retrieving specialized data services
To accomplish the goal of providing user-friendly public access to the geodetic control network databases, descriptions and photos, an interactive map using GIS data and ESRI’s ArcInfo and ArcView software has been developed. In this study, an IMDC (Interactive Map of Dhaka City) was prepared showing a variety of features. With an interactive map, the user can specify the kind of display of the map he prefers or the kind of analysis or query he would like to perform with the stored data through the use of a Graphic User Interface (GUI). The display of the map would change and the results of analysis would be shown on the fly. The exercise provided insights and skills that would be required if the study is carried out further to include more powerful planning routines.
The project developed is a preliminary instance of such work in the field of GIS. It is hoped that this study will provide a base for more detailed and comprehensive research in future and act as a useful guide to create other such applications.
Base digital map of Dhaka City
A copy of the Dhaka Guide Map was collected from the Survey of Bangladesh. The scale of the map is 1/20,000 or 5 cm to a kilometer. The following features were digitized:
The digitizing process has been carried out on-screen using scanned images of the paper base map as guides. Different features were digitized as separate themes shown in Fig. 1. After the digitization process, topology was created, errors were identified and corrected, and attribute data was added to each coverage. A number of Simple Macro Language routines were used to simplify the repetitive tasks.
Implementation of interactive functions
Avenue is the customization and development environment for ArcView. It is an object oriented scripting language that is fully integrated with ArcView. With it one can perform the following tasks (ESRI, 1996, p. 1):
- Customize the way ArcView looks,
- Modify ArcView’s standard tools,
- Create new tools,
- Integrate ArcView with other application,
- Develop and distribute custom application on top of ArcView.
The search option is used to find a particular feature in a view. It gives a list of features and makes a theme, that the user specified from a list, active in the view and finds a feature. When a feature is found, ArcView selects it and pans the view so that the feature is in the center of the view. Features highlight on the view when they are selected and remain highlighted until a different selection is made, or until they are deselected. By default, selected features highlight in yellow and zooms to the spatial extent. Search is a quick way to select a particular feature of interest.
The Hotlink tool enables the features of a view to link with different objects. Hotlink helps accessing of virtually any data or application directly from a view. For example, one might click on a building to display its floor plan, click on a land parcel to review its legal documents, or click on a country to play a video about it. A hot link is followed when a feature in a theme is clicked with the Hot Link tool. To see a feature’s images and descriptions the user has to locate that feature with the help of search function.
Incorporation of the digital map with the interactive functions
In a graphical user interface (GUI), the digital map was incorporated with the interactive functions by creating new controls and adding them to the interface. Changes were made in the ArcView's interface for view document shown in Fig. 2. Two new controls were added to the interface - a Search button and a Display tool. The scripts for searching a feature and displaying graphics and text descriptions of features were assigned to the button’s 'Click' property and the tool’s 'Apply' property respectively. These two scripts were named as View.Highlight and View.Display respectively mentioned in Appendix. These controls were defined by giving icons and help messages. The 'S' icon for search function and the 'Frame Picture Icon' for display function were selected. When the cursor is placed over a button and a tool its function is indicated by a message displayed on the status bar.
Searching a feature in a view
To search a particular feature on a view the user has to get a list of names from which he will choose an option. Then the chosen option will be highlighted in the view. The user can find a feature in the following way:
- When the search button is clicked a message box containing the list of themes is presented shown in Fig. 3.1.
- After selecting a particular theme, the OK button has to be clicked. It will bring up another message box with list of names of the features in the selected theme shown in Fig. 3.2.
- The selection of a name from the list will highlight and display the associated feature in the center of the view shown in Fig. 3.3.
Displaying images and information
The action and the field are specified in the Hot Links panel of the Theme Properties dialog. Each theme in a view can have its own hot link definition. There is no default hot link definition. Hot links have to be defined before they can be used. Pathname of graphics and text has to be given in a specific field of the attribute table to access picture and information. If after clicking on a feature a beep sound occur it means that ArcView cannot find the application or file defined for that feature. The user can gain access to pictures and information of a particular feature in the following procedure:
- First of all the Search button has to be clicked. Consequently a message box containing the list themes will appear.
- The OK button has to be clicked after a particular theme is selected. As a result another message box with a list of names of the features in the selected theme will show up.
- After clicking the OK button again, the chosen feature or field will be highlighted, zoomed in and presented in the center of the view with.
- Then the Hotlink tool has to be applied on the selected feature. Such action will display the related information and images.
Fig. 2: Customization of ArcView Interface
Fig. 3.1: Message box containing list of themes
Fig. 3.2: Message box containing list of features in the selected theme
Fig. 3.3: The associated feature is highlighted and displayed in the view
Fig. 4: Hotlink action displays the beautiful image and information of ‘National Museum’
Conclusion
The paper describes the preparation of a GIS-based interactive map of Dhaka City integrated with few extended capabilities which can be used as a guide map. ArcInfo and ArcView GIS software are used to prepare the interactive map, which includes preparation of digital map and customization of user interface. For this purpose software and hardware were used to capture, store and organize, manipulate, analyze and display spatially referenced information. The system, including its graphical user interface, was implemented with PC ARC/INFO's Simple Macro Language and ArcView's Avenue Programming Language. In this study, an attempt was made to prepare an interactive map of Dhaka City showing a variety of features. But due to constraints, only some rudimentary interactive features were included, but the exercise provided insights and skills that would be required if the study is carried out further to include more powerful planning routines. Also, this study has tremendous scope in different activities of planning and other field and can serve as a basis for future relevant research and studies.
References
- Anonymous (no date) IFLA Section of Geography and Map Libraries, http://magic.lib.uconn.edu/ifla/.
- ESRI (1996) Avenue: Customization and Application Development for ArcView, Redlands, CA., USA, p. 1.
- Pfister, B., Burgess, K. & Berry J. (2001) What’s a Map? - Media Mapping Technology is Redefining the Term, Geoworld, Vol. 14, No. 5, p. 43.
- Pictographics (no date) Pictographics' GIS and Internet Mapping Solutions, http://www.pictographics.com/gis.lasso.
- Star, J. and Estes, J. (1990) Geographic Information System – An Introduction, University of California, Santa Barbara, Prentice Hall, Inc., p. 175.
Appendix
List of Avenue Scripts
1. View.Highlight
theView = av.GetActiveDoc
theThemeList = theView.GetThemes
YourChoice = MsgBox.ChoiceAsString(theThemeList, "Choose a Feature", "Different Features")
if (not (YourChoice = nil)) then
a = theThemeList.Find(YourChoice)
theThemeList.Shuffle(theThemeList.Get(a), (theThemeList.Count))
for each t in theView.GetActiveThemes
t.SetActive(false)
end
theThemeList.Get(theThemeList.Count - 1).SetActive(true)
theView.InvalidateTOC(nil)
theView.GetDisplay.Invalidate(true)
for each t in theView.GetActiveThemes
theFTab = t.GetFTab
theField = theFTab.FindField("Name")
NameList = {} 'initialize list of names
for each rec in theFTab
val = theFTab.ReturnValue(theField, rec)
if(val <> "") then
NameList.Add(val)
NameList.RemoveDuplicates
NameList.Sort(True)
end
end
aChoice = MsgBox.ChoiceAsString(NameList, "Choose a Name", "Names")
if (not (aChoice = nil)) then
av.UseWaitCursor
theBitmap = theFTab.GetSelection
expr = "([Name] = "++aChoice.Quote+")"
theFTab.Query(expr, theBitmap, #VTAB_SELTYPE_NEW)
theFTab.UpdateSelection
av.GetProject.SetModified(true)
r = Rect.MakeEmpty
for each t in theView.GetActiveThemes
if (t.CanSelect) then
r = r.UnionWith(t.GetSelectedExtent)
end
end
if (r.IsEmpty) then
return nil
elseif ( r.ReturnSize = (0@0) ) then
theView.GetDisplay.PanTo(r.ReturnOrigin)
else
theView.GetDisplay.SetExtent(r.Scale(1.1))
end
end
end
end
2. View.Display
theGIFFileName = Self.Get(0)
theTextFileName = Self.Get(1)
MsgBox.Info("One moment please..."
+NL+"Hit OK to continue.","Multi Hotlink")
if (File.Exists(theGIFFileName.AsFileName))
then
theImageWin = ImageWin.Make(theGIFFileName.AsFileName,theGIFFileName)
else
MsgBox.Info("There is no Image File","")
end
if (File.Exists(theTextFileName.AsFileName))
then
theTextWin = TextWin.Make(theTextFileName.AsFileName,theTextFileName)
else
MsgBox.Info("There is no Text File","")
end
if (theImageWin <> nil) then
theImageWin.Open
theImageWin.Resize(240,180)
theImageWin.MoveTo(1,100)
end
if (theTextWin <> nil) then
theTextWin.Open
theTextWin.Resize(240,180)
theTextWin.MoveTo(240,100)
end
Link Script
theView = av.GetActiveDoc
found = FALSE
listofFieldNames = {"GIFField","TextField"}
listofValues = {}
p = theView.GetDisplay.ReturnUserPoint
t = theView.GetActiveThemes.Get(0)
if (t.Is(FTheme))
then
found = TRUE
theFTab = t.GetFTab
rec = t.FindByPoint(p).Get(0)
for each f in listofFieldNames
theVal = theFTab.ReturnValueString(theFTab.FindField(f),rec)
if (theVal <> NIL)
then
listofValues.Add(theVal)
else
listofValues.Add("a")
end
end
end
av.Run(t.GetHotScriptName,listofValues)
if (not found)
then
System.Beep
end