Remember the good old days when the geography teacher would give assignments of locating the position on important cities. She would probably never have dared to give a complex assignment like finding probable regions where both the climatic and the soil conditions are good. Times are changing and along with it technology. Now nobody flips the pages of an atlas to search “Patagonia”. The trend is to insert an interactive atlas CD into a computer and find it. But there are limitations in that, as one cannot query the intelligent maps and analyse the displayed maps. In order to solve this problem GIS was developed. From interactive CD, people moved to GIS. But not all could afford the usage of GIS. Around the same time Internet was fast catching the imagination of the scientific community and merging Internet with GIS resulted in the next technological innovation – ‘Internet GIS’.The need for convergence of the spatial technology with the Internet arose primarily because it is a cost-effective technology in which the user does not have to spend on buying software or mainting them. Morever, Internet has become a commonly utilised tool for easy access and dissemination of information. For non-GIS users, Internet GIS is proving to be a boon as Internet brought with it an user friendly environment which anyone could access and use. It has also been designed to support all possible database so that anyone can access as well as disseminate data.
Internet GIS is like a common platform for professionals and amateurs in mapping science field, providing them flexible tools for manipulating the available map data and experimenting with their graphic presentation on the computer screen resulting ultimately in the production of an ‘optimal’ map which can be used for producing an analogue output in the form of a paper map. Maps on the Internet are graphic representations of the paper maps which can be used to communicate and analyse geographic data. Integration of Internet and GIS is causing a transition from mere ‘graphical representations’ of paper maps to ‘interactive maps’. These interactive maps have a number of intuitive tools to access and interact with such that the multi-dimensional geographical information provided in the Internet help map-users to actively participate in not only evaluating the spatial data provided by Internet but also visualise the maps in accordance to the liking of the map-user.
Image courtesy Chris L. Hogan
GIS as a science started long before the Internet revolution. In the ’80s, the advent of GIS revolutionised geography. Complex analysis work which took ages to be compiled was now over within days. But a need to share the information about the technology was felt. At the same time a technology for transfer of information and data was being devised which caught up in the ’90s in the form of ‘Internet’. The coming of the Internet proved to be another technological revolution to the mapping world. GIS could not be left behind in the race. Moreover it was felt that the main bottleneck for the spread of GIS in the society was not only the lack of awareness but also the cost factor. GIS softwares were very costly. Only elite universities and research organisations could afford this type of expenditure. Universitites soon came out with their own GIS softwares which were freely available. But the need for spreading the use of these softwares came into focus. Internet proved to be the best medium for the spread of these softwares.
The benefits of putting GIS services on to the Internet was too large to be ignored. Soon private organisations too jumped into the race and this resulted in expanding the available market. GIS software giants began to modify and design their softwares for the Internet users. The trend continues till date and the Internet GIS market is expanding day-by-day. However, the main blockage in the field is the same problem which all other users of Internet face – the bandwidth problem.
Internet started off with a simple Hyper Text Markup Language (HTML), a primitive markup language for transferring information from Web Servers to Client’s browser by describing hypertext links between documents and simple text and image formatting. But Internet GIS cannot be operated with such simple low level language. To increase the functionality of the web browsers and for more complex computing application on the Internet, other ‘object technologies’ had to be incorporated. The main ‘object technologies’ presently available are the Java™, CGI/Perl and ASP. The language of Internet is Java™ which was developed by Sun Microsystems. It can be compiled into a form suitable for running in a Java™ Virtual Machine (Java VM). Java™ can be used to write or develop small applications or ‘applets’, which run on Java™ Virtual Machine by a web browser. Once the web page is opened, the applet gets downloaded automatically and runs the application inside the ‘browser’. Because of this applet, one does not have to respond to the web server each and every time for running an event. Small functions are easily handled by the applet itself.
Common Gateway Interface (CGI) is considered as a standard specifying the manner in which an external programme can be used by a webserver. The CGI programmmes can be used to process data submitted in the browsers and also support web applications like clickable image maps.
Common Object Request Broker Architecture (CORBA) is an architecture designed to develop applications as a set of cooperating components. In this the components communicate via an Object Request Broker (ORB). The interfaces that the components expose and through which they communicate with other components is defined using an Interface Definition Language, or IDL. CORBA allows components written in different languages to communicate with one another. Furthermore, the components need not reside on the same machine, nor be run under the same operating system.
ActiveX was developed by Microsoft and is a component architecture exploiting Microsoft’s Component Object Model (COM), an object technology designed for deployment over the Internet. Internet GIS as of today can successfully perform only a few basic functions like displaying the selected geographical area, displaying the geographical datasets and features of the selected area, displaying the type of features to be viewed, low level interaction with the displayed maps, etc.
The geographical area can be displayed by either searching the geographical area provided by the user or by simply clicking on the map-area which is required for display. The user is presented with a large variety of options for displaying the datasets. Usually the dataset of the selected area can be seen by clicking the right mouse button when the mouse is placed over the selected area. Other methods of displaying datasets are also available like separate web pages showing the datasets, displaying the datasets along with the map on the same page, etc. Many sites provide options wherein the user can display the type of features he wishes to view and also alter the style of presentation of the display by changing the display parameters. Almost all the websites provide simple and basic level of interaction with the maps. This includes simple zooming and panning facilities on the map. Some of the advanced sites allow the users not only to zoom and pan the surrounding area but also provide attribute information about the surrounding area without actually contacting the webserver.
The working of Internet GIS sites is fairly easy to understand. The user puts up a query which is sent to the web server. The web server directs the query to the application server which processes the query and searches for the required output from the Map Server. The reqired output is received by the Application server from the Map server which creates an HTML form of the map which the user views. At present the results of most of the queries are in the form of image files (GIF, JPEG etc.). Some websites also provide the option of upgrading the user’s computer to meet its requirement by downloading certain essential components into the users computers. This allows the users to access the maps, many of which are such that they can be viewed only by GIS software. There are certain technically advanced sites which when accessed invokes an applet which cause basic information and simple data to be stored temporarily within the user’s computer. As a result of this the user can access simple information like house data, street data etc. and perform simple functions like zoom and pan without contacting the web server. This saves precious time which is vital in the Internet world.
But what the present Internet GIS sites lack is the interaction from the users side. The user has to work with the map or data provided by the site. The user cannot import his own dataset and do analysis work on it. This is perhaps a drawback of the present Internet GIS sites. However, technology moves with time and already technologies are being thought of and devised wherein the user can access any database he wishes to work upon and log on to an Internet GIS site where he would use his own data to prepare maps and do the analysis work with the data produced. Thus the whole analysis work is done in an Internet GIS site. It will not only save the users precious time, but also save him from buying the costly GIS softwares. The future really sounds cheap and bright !
Drawbacks in Present System…..
The primary functions of the Internet GIS sites as of today is to retrieve, manipulate and display geographic information. Interactivity with the users in performing these functions is often at the cost of users precious time which is also felt by the Internet industry. Apart from the low bandwidth of the Internet, the major draw-backs of the Internet GIS sites are as follows:
Limited interface and interactivity
The present sites provide options for only limited interactivity like panning and zooming. More sophisticated actions are beyond the scope of simple HTML and CGI. As a result of this a ‘dumb’ map is created which although is a rich source of information, leaves no scope for obtaining more information from the map by interacting with it. In future web mapping can be used to query and actively interact with the maps.
Web mapping as of now is totally dependent on interaction with the web server. Any function or query first reaches the web server and then on to the map server which processes the query and sends back the result through the same route. If the network traffic is heavy then the complete transaction takes a lot of time. In future applications will be designed such that the map server itself rests on the web server such that people can access any database and use the web server for analysis.
Need for Improved functionality in Internet
A mentioned earlier simple HTML and CGI cannot be used for performing complex functions within the Internet. For such solutions new technologies have to be developed. Already Java™ and Tcl/Tk are demonstrating enough potentials for use in Internet. Further research has to be done with respect to developing better interfaces for Internet GIS. Furthermore, the absence of any standard language for storing geographic information is probably one reason for obstacles in the growth of Internet GIS. The Open GIS Consortium has proposed the Geography markup language (GML) which is an XML encoding for the transportation and storage of geographic information, including both the geometry and properties of geographic features. If such kind of a standard language is adopted by all then there would probably be no need for need for conversion of data types. This will cause uniformity in the availability of data throughout the Internet regime.
In the end it is to be realised that the basic Internet mapping architecture has been developed, but its application to a particular field has not been complete in a true sense. Much more has to be done in that respect. The future depends on the type of products the Internet GIS vendors succeed in bringing out which in turn depends on how well they can perceive the needs of the Internet GIS community.