Home Articles Low-cost internet/intranet enabled graphics viewer for GIS applications

Low-cost internet/intranet enabled graphics viewer for GIS applications

D. M. Bedekar, S. M. Kharad, and Y. T. Pokharkar
L&T Information Technology Ltd., Plot 200,
Shil – Mahape Road Navi Mumbai, 400 701
[email protected]

 

Preamble
The costs associated with the implementation of a GIS are often perceived as prohibitive. This is particularly true of small and medium enterprises, which operate under tight budgetary constraints. The paper proposes a technical solution, which can help to mitigate the problem and enable the organization to derive the benefits of implementing a GIS. The paper describes the development of a low-cost Internet enabled graphics viewer, which has been successfully implemented in an intranet-enabled GIS Application.

Network capability of current Internet GIS applications
The Internet has emerged to new heights within the last few years especially in developing countries. Also it is inexpensive and ubiquitous and renders "information like water". This makes it a perfect vehicle for carrying the GIS to the users across the globe. Current version of HTTP protocol does not support direct transfer of vector data type, which most of the GIS applications require. Hence the Internet users are not able to analyze and display vector data. As a result, GIS applications require:

  • More time for transfer of data between client and the server
  • Extra burden for repeated processing, like map Navigation, visualization and analysis.

This mainly happens because of the system architecture used. Typically the process involved is that the user sends a query to the GIS server, which initiates a function to convert the vector data into raster format. The raster file is then returned to the browser for display.

What LTGIS Tool can do for GIS applications on the Internet/Intranet?
The heavy network traffic caused by frequent data transmission in existing Internet-enabled GIS systems, served as a catalyst to developed a new solution, which will enable users to download objects from the network GIS server to their local machines and make use of them locally. This will solve the problem of data transfer.

System Architecture:

The LTGIS Tool – A Internet enabled GIS

Development Environment
Languages: Microsoft Visual Basic 6.0, Win32 API, and XML
Databases: Microsoft Access.
Server: Win NT 4.0, Microsoft Internet Information Server 4.0

Hardware/Software Requirement for the client

  • The user system should have minimum 32 MB RAM computer (64MB recommended)
  • Pentium Processor
  • The application could be best viewed in Internet Explorer 5.0 with 800 * 600 resolution.

Component of LTGIS Tool
The LTGIS tool has two major components, I. The Data Converter
II. The Viewer

I. The Data Converter
The data converter component resides on the server and is responsible for converting the data from a standard DXF file to the LTGIS data format, which is readable by the Viewer, deployed onto the client machine.

II. The Viewer
The Viewer is an ActiveX control, which displays the drawing files (vector maps) with basic entity like line, arcs, point and text. The viewer is capable of rendering the vector data directly, which is downloaded from the server when the user accesses the map for the first time. Thereafter, there is no transaction between the server and the client for any of the vector map data unless user requests for a different map or retrieves attribute data.

The Viewer accepts the data from the Server in the form of XML strings. Hence the Viewer can display any data format. Once the Viewer receives the data there is no interaction with the server as far as the basic GIS functionality is concerned. The map navigation and other GIS functionalities are performed at the client end. Hence the process reduces the network traffic and increases the overall performance of the application.

Figure 2: The Viewer

The functionalities supported by the Viewer (Fig. 2) are listed in next page.

 

 

 

The Map Display Area
This is the area where the map data gets rendered. The Map Display area has eight triangle-shaped buttons these buttons provide direct panning of the map in the eight cardinal directions.

Aerial View
This functionality shows an overview of the entire map. The extents of the "Map Display Area" are indicated by a rectangular outline in the Aerial View. At each instance of map Zoom In, Zoom Out or Pan in the Map Display Area, the rectangle is changed to show the current state in "Aerial view". The Aerial View also supports Pan functionality by holding and moving the rectangle in the Aerial view window.

Map Navigation:
The viewer provides basic Map Navigation functionalities like –

  • Zoom In – This allows the user to zoom to a specific area. The "Zoom In" can be performed by any of the following methods-
  • Zoom in By Window – allows zooming in by creating a window in the Map Display area.
  • Zoom in by Point – zooms in on click of the mouse.
  • Dynamic Zooming – This corresponds to the direction of the mouse movement. "Zoom In" when the mouse is moved upwards, and "Zoom Out" when the mouse is moved downwards.
  • Zoom Out – This supports the "Zoom Out" function.
  • Pan – This allows panning of the map.
  • Full Extent – The complete map is displayed in the Map Display Area.

Identify
This functionality provides for selecting individual entities on the map and displaying the relevant attributes attached to it.

Map Name Display area
This functionality displays the name/title of the map being selected. This is an added functionality, which would be useful if the user is working on various categories and numbers of map

Search
This functionalities searches for the graphic entities, which the user wants to locate, for which the tool exposes some APIs through which the user can pass on the information about the entity to search. (This functionality is not seen in Fig. No: 2)

Further Enhancements
During user testing one major finding was that additional functionalities are required to enhance the quality of the Viewer. Some key functionalities as mentioned below, could be included in system to make it robust, user friendly and satisfy the basic needs of the GIS users.

  • Symbol library – This would hold all the possible symbols that could be used for point objects.
  • Allow Layering – This would facilitate handling layers Visibility and layer Selection.
  • Query functionality – Query builder would be added to perform SQL queries.
  • File Support – This would allow the user to select ESRI Shape file format. On completion of this functionality, the Data converter component would be able to convert the shape file data to the LTGIS data format. This would help increase the customer base, for the tool.
  • Browser Support – Currently the Viewer supports Internet Explorer. This would be expanded to support Netscape browser.

Usage
The tool is very useful for corporate world as well as for industries that are wide spread in term of geographical areas and business, where tracking of human resources & business-related assets is very critical, time consuming and laborious. The "LTGIS" tool is a cost-effective solution, where such industries can overcome their problem in locating resources, facilities, and their whereabouts and associated attribute data, maintaining consistent database of their resources through out the organization, at the fingertip by just a single click. The following case study illustrates an effective implementation.

Case Study – Employee and Facility Information System (EmFIS)
Knowing "what is where" is a question of fundamental interest, and corporate set-ups are no exception. The answers provide for optimum utilization and efficient management of all resources. The Employee and Facility Information System (EmFIS) is a tool that addresses and facilitates the management of human resources. It handles queries and provides solutions involving spatial relationships, through a decision-making process. The software offers a pleasing and user-friendly interface and depicts solutions in a graphical form.

The Application
EmFIS is for the management of human resources and facilities, which in many organizations are geographically distributed over several buildings and at different locations. Therefore the need for a GIS application was identified to process spatial queries and provides solutions involving spatial relationships. This would in turn aid optimum utilization and efficient management of all resources in term of occupancy and space. Further it ensures consistency by maintaining a single database throughout the organization. It helps in allocation & deallocation of human resources, identifying latest employee location, finding vacant areas for suitable usage and facility available.

Traditionally, maintaining employee records is a laborious procedure and is usually centered around the HR department. Acquiring information related to employees can be facilitated by developing a Web based GIS solution. This application will help in locating employees, along with HR details, telephone extension, facilities allocated etc.

Development Environment
ActiveX Control: MS Visual Basic 6.0
Tool: LTGIS Tool
Internet: MS Visual Studio 6.0, ASP 2.0, IIS 4.0, XML, MS Access 97, JavaScript, and VBScript

The Functionalities provided by the EmFIS

  • Proper login & Security facility.
  • Listing of employees building wise, department wise and floor wise.
  • Search/Find employee facility.
  • Display the HR attributes along with photo of each employee and tel. ext. in accordance with the permissible fields that can be viewed.
  • Online updating of personal data.
  • Invoking the e-mail Facility through the application
  • Map Navigation Functionalities like Zoom In, Zoom Out, Zoom Extent, Pan,
  • Identify and Search.
  • Allocation / Re-allocation of employee

Conclusion
In cases where the requirements of a GIS application are limited to basic functionalities, it may not be possible to bear the burden of expensive GIS software. The LTGIS tool provides a cost-effective alternative. Also the design of the tool makes it a viable solution for the Intranet/Internet deployment, as there are very few interactions between the server and the client hence tackling the problem of heavy network traffic.

Acknowledgements
The authors wish to acknowledge the contribution of the Mr. S.V. Bhosale, GIS Team at LTITL and Mr. P. Ramakrishna (formerly of LTITL) in the development of this Viewer.