The integration of different data sources in GIS has received incressing emphasis as a result of new development in computer and GIS technology. The integration of various data sets to fully utulize complementary information has become an important component. Four integrating methods, namely, colour space transformation, principle component analysis, high pass filter and radiometric method, are investigated. To evaluate the result of different merging method, six measures are used. They are visual inspection, correlation, root mean square error, difference of two images, entropy values and the histogram comparison.

As computer technology progresses, the development of GISs tends to combine vector and raster functionalities into an integrated system to provide more extensive function. In this study, the requirement for an integrated GIS and the characteristics of vector and raster data were taken into account to analyze and design an integrated geographic database. The geographic database is based on an object-based data model with appropriate data structures for holding both vector and raster data. Furthermore, a prototyped geographic database system for IGIS was implemented using persistent database program­ming languages. Real geographic data was used to test the capability and performance of the proto­typed geographic database system. The experimental results of this research show that the integrated database can display vector and raster data separately or have the superimposition of them in a window. The prototyped database system can also support information queries for the vector 、 raster or attribute data of geographic objects. The paper concludes that the proposed approach for the design of an integrated geographic database is capable of managing varied geographic data in a single database environment, and the designed database may be used as a foundation for the further development of an inte­grated GIS.

Microwaves from satellites can be used for rainfall rate retrieval by two different methods -- a statistical based algorithm or a physical based algorithm. Until now the statistical based algorithm has been more frequently applied because it is less complicated. However, the physical based algorithm provides the best method to reduce estimation retrieval bias. It can be simplified by reducing the number of unknown parameters such as surface emissivity, water vapor content, temperature profile, and cloud height. GMS infered data and RAOB data were used to estimated some atmospheric parameter and which were treated as known parameters. The most uncertain factor is surface emissivity over land which was resolved by NDVI (Normalized Differential Vegetation Index). Of the many physical based methods, the nonlinear simultaneous algorithm of determining rainfall rates proved to be the best. Rain gauge data over land was compared with satellite retrieved data. Area rainfall rate determined by the ATI (Area Time Integral) method was considered as ground true. The accuracy of the rainfall retrieval results in whole 1996 near Taiwan area were compared, most of nonlinear retrieval method are better than SI method which is the best statistical method in Taiwan area. The accuracy of stratus rain rate estimation was worse than cumulus rain rate estimation because cloud structure was difficult to determine and the cumulus pattern was assumed is all cases. Also when instant wind speed exceeded 30m/s and rainfall rate was over 50mm/hr, SSM/I rain information was reduced for it is close to instrument saturation.

The relations between the scale of a map to be produced and the scale of the source image, are important factors for both economic and quality aspects of mapping. In this article, a new index, RIQ (Relative Interpretation Quality) and its digital counterpart, RDQ (Relative Digital Quality), are investigated. The traditional C-factor and the empirical equation are also used for comparison.