Analysis for quality control in database input for making GIS


M. D. Joshi
Sardar Vallabhbhai Patel Institute of Technology, Vasad, Mailing Address: Sardar Vallabhbhai Patel Institute, of Technology (SVIT) At & Po. Vasad - 388 306, Dist: Anand , Gujarat
Tel: 02692 74766 , 74 357, Fax No. : 02692 74540
E-mail - maheshduttjoshi@yahoo.com

R. Sivakumar
Department of Science and Technology, Mehrauli Road, New Delhi 110029


Abstract
Accuracy of data plays a very important role in the development of a GIS of any area. This is one of the prime factors governing the reliability of information as obtained from the GIS and hence the decision making. Reliability of a Geographical Information System (GIS) mainly depends upon its accuracy with which the data is arranged and the way it is integrated and displayed for the purpose of extracting information for decision making. Since decision depends on the information contents, the accuracy of such information is hardly required to be over emphasized. In order to be sure about the accuracy, it is necessary that the data conversion is tested and compared against the data sources, considering prescribed accuracy standards.

In order to assess the magnitude of errors at various stages of computerization of information from the source data, it is necessary to consider various factors likely to affect the accuracy. The quality standards are such that some of the aspects are related with the figures and ratios whereas some others emphasize on relative quality. However, there are five quality indicators of accuracy given in the US spatial Data Standards (Clarke, 1992) to consider a good quality GIS. There are Lineage, Positional Accuracy, Attribute Accuracy, Logical Consistency and Completeness. These have been considered in the present study.

It is necessary that the data conversion from the data source to the computer database is tested taking these factors into account. The same has been attempted in the present study to present a case for developing a quality Control method. It has been attempted in this study to incorporate as many data conversion from different sources as possible and the results obtained were found to be related to aspects of quality control in a given situation.