Rajen M. Tamhane, Ajay S. Deshpande
Scientist, Maharashtra Remote Sensing Applications Centre, Dept. of Planning, Govt. of Maharashtra VRCE Campus, South Ambazari Road Nagpur – 440011, Maharashtra Tel: +91-712-238576/220086
An Approach at MRSAC for the development of structured, standardised and large GIS datasets
Accurate and reliable information regarding natural resources and socioeconomic parameters is very important for planning purpose. The increasing population pressures coupled with natural disasters are taking heavy toll of this precious wealth. Our survival depends largely on preserving these natural resources. The advent of computing technologies coupled with the development of advanced technologies like Remote Sensing and Geographical Information System (GIS) have increased the potential for creating and maintaining database using geographical space as a key-field. The geographic database prepared using these tools can then be used for arriving at important conclusions regarding the natural resources. The structured database availability provides the vast potentialities for geographical analysis to be carried out for specific applications.
The hardware and software technology has developed in leaps and bounds in the recent past. The availability of various GIS software packages configured on high-end workstations to desktop computers has made data processing much faster. However, database generation is still the most challenging job. Large amount of efforts in terms of man and machine hours are required to be put in for the database generation in standard formats.
The database generation in a standardised form is an uphill task and cannot be a perfect result when done independently through the basic tools of GIS software. The stipulated time frame for database generation is also a factor to be kept in mind. The database development can be visualised to be quite cumbersome task when done through the basic GIS operations and commands.
The challenges mentioned above lead us at MRSAC to the development of database structuring tools (DBS-TOOLS). The database structuring tools is a menu driven, user friendly customised software package built over ARC-INFO using the Arc Macro Language. The software aims at development of standardised database with all the necessary key fields/items. The software is a group of modules which takes care of various steps of database generation and standardisation.
The Felt Needs
While working on the various projects which involved the use of geographic database in a digital environment, some important aspects have emerged which need to be addressed in a systematic manner to reduce redundancy in the database creation process. These formed the guiding factor for development of the “DataBase Structuring Tools” and are summarised below:
- The database generation is the single most important activity in any project on which results of analysis are dependent;
- The database generated should be standard and compatible to universal databases;
- The activity should be completed in a stipulated time frame through data automation techniques;
- The same database when ported to desktop platforms should be compatible for customisation there.
The Need for a Toolset
The advent of GIS technology has brought with it the various application projects. To quote a few mega projects are the National (Natural) Resources Information System (NRIS), Disaster Management Information System(DMIS), Wasteland Management, Roads Information System etc. The above mentioned projects require data on all the basic thematic layers like landuse/cover, geomorphology, geology, structures, soils, watersheds, drainages, roads, rails, district and tahsil boundaries etc. for the entire state/region.
The Database Structuring Tools (DBS-Tools): At A Glance
|The tool||A coustomised Software package|
|The system used||Silicon graphic workstation 02/indy, HPworkstation|
|The operating system||Unix platform|
|The customization tool||ARC MACRO LANGUAGE|
The geographically referenced database of large volumes is today viewed as an integral part and parcel of all the major decision making processes. The need of the hour is the adoption of standardised procedures for development of large databases. This was sufficient reason for putting in an effort for the development of “DBS-TOOLS”.
Organisation of the “DBS-Tools”
The automation level starts at the ARC level. The arc prompt when invoked gives an option window for selection of the normal arc prompt or the DBS-TOOLS window. If the DBS-TOOLS option is selected, the area of interest (district) is accepted from the user along with a password (compulsory).
DBS-TOOLS starts with the main menu. The main menu displays the various modules which can be invoked as per the operational steps of database generation. The various modules are arranged in the order of left to right on the main menu, assuming the normal established steps of database generation starting from import of data through verification, correction (geometric and geographic) to advance features like composite map preparation.
The various modules are independent entities and can be invoked one at a time or in association with the other modules as and when required in the intermediate steps of database generation. The user is guided from time to time on various automated processes which database is subjected to depending on the status of database generation.
A most vital feature of the DBS-TOOLS is the generation/extraction of base information for the user in a digital format. The user gets a complete set of required base information including the Survey of India toposheets grid reference, the toposheets numbers in the selected district (AOI), and administrative boundaries from the SOI toposheets like the district and tahsil boundaries. This helps the user in saving a lot of initial time and the user is required to refer to the maps and the toposheets only when the map errors (if any) are to be verified. The concept of the DBS-TOOLS is shown in the Figure 1.
Fig. 1: DBS Toolss
Salient Features of the DBS-Tools The following areas emerge as important from the resultant activity point of view.
- The customised tool is an open system with a structure that can be easily modified if required by the specific project and user needs.
- As the database generated is in a known and standard format any user can work smoothly on the resultant database.
- Modelling is easy on such structured and known database.
- Some of the elements both spatial and non-spatial are dynamic in nature and requires updations at regular intervals. The database thus generated also provide a much more flexible option for updation which forms a key element in any information system.
- Customisation on the desktop platforms is easy without any difficulties regarding the use of variables and constant as these things are already created in a standard format from the high end machines on which the database was generated using the DBS-TOOLS.
The DBS-Tool has been used practically for generation of FIVE district database on 1:50,000 scale at Maharashtra Remote Sensing Applications Centre under the Disaster Management Information System (DMIS) project. The entire source code of the software is purposely left open without encryption and is available for modifications as per the project and the user need. The various resultant benefits are summarised below:
The effort of developing DBS-TOOLS should form an example of compliance with national efforts being carried out for the standardisation of the databases being generated in all the organisations in the country. An example of the policy of standardisation experience regarding the structure of GIS datasets is the policy designed and published by Space Applications Centre, ref – “Node Design and Standards”.
The turn around time for data generation is drastically reduced resulting in the increased capability for the user to handle more study areas and also find more time for data modelling and allied activities. Also the process of data generation is simplified thus allowing a smoother approach of working.
|Modules of DBS-Tools
The separate modules that are responsible for various independent tasks are described below:
|IMPORT||Includes data import from various compatible data import and interchange formats.|
|VALIDATION||Checks for correct registration points, nomenclature attributes standardisations, data gaps if any, etc.|
|PROJECT TRANSFORM||Registration to a common reference system and all geographical corrections are taken care here.|
|TOPOLOGY||The required topology of all the covers is automatically checked and build here.|
|ITEMS MANAGER||This module takes care of the standardisation part as for the similar items are concerned.|
|PROCESS||The actual processing on the map for labels and arcs, etc.|
|VIEWER||The available covers can be viewed on any item in the coverage and in global perspective of the district.|
|WORKSPACE MANAGER||The normal requirements of cover management are dealt by the workspace manager module.|
|ADVANCE-FUNCTIONS||The advanced functions like map joins/append, clipping the area of themes with the district area etc. are carried out with this module.|