NATIONAL TOPOGRAPHIC DATABASE INFORMATION MEASURING -CASE STUDY IN GLOBAL MAPPING AND WESTERN MAPPING PROJECT

摘要

The western mapping project is using a series of advanced satellite mapping technology to complete the unpopulated 1:50 000 topographical surveys in China. It provides the related products of 1:50 000 scale topographic maps from year 2009 to year 2010 continuously. These applied the new technical manufacture products urgent to carry on the product information content appraisal and quality analysis, thus they could have the conformity with our country's existing database. At the same time the previously constructed topographic databases including 1:250 000 and 1:1 000 000 scales are needed to be updated from large scale to small scale gradually. Entropy is a kind of information quantity evaluation based on information theory and mostly applied to measure of map information. The authors briefly review the entropy application in geographic information measuring, and then provide the conceptual models of core features information in topographic database. The authors do some research works in the case of 1:50 000 topographic database in western mapping project and 1:1 000 000 topographic database in global mapping project. These research works focus on the geometric information such as measure or form information, topographic information such as connection or order, and attribute information. Two case studies have been accomplished. One of them is about the joint entropy measuring for the small scale map and the other is about the form information measuring for large scale ones between the new and old databases. The studies show that the information theory has effective application in geographic information measurement, and there is some quantity relationship among those different scale terrain maps through the information measuring based on information theory and entropy properties. To some extent these relations provide the basis of information quality and quantity control while updating databases.