IDRISI

IDRISI is a geographic information system (GIS) with a strong focus on data analysis and image processing tools. It was developed at Clark University under the direction of Ron Eastman, beginning in 1987, and is now supported by Clark Labs, a nonprofit research and development laboratory within the Graduate School of Geography. Since it emerged from a research institute as a noncommercial product, it is in widespread use in the geographic information research community and in the international development community.

IDRISI is named after Abu Abd Allah Muhammed al-Idrisi (1100–1166), a geographer and botanist who explored Spain, Northern Africa, and Western Asia. Initially, IDRISI was typical of systems intended for expert academic users. On one hand, it provided a number of sophisticated tools that were not offered by other GIS (e.g., fuzzy logic). On the other hand, IDRISI was not easy to use, since it had not been designed as a general-purpose, commercial GIS. Therefore, IDRISI needed some expertise to be used, which limited its general applicability.

Since those early days, IDRISI has evolved into an internationally used GIS that offers both geospatial data analysis and the functionality to process remotely sensed data (i.e., satellite images). In the current version, IDRISI consists of more than 250 tools, including a wide range of image processing and surface analysis tools, and advanced capabilities, such as multicriteria evaluation, time-series analysis, hard and soft classifiers, neural network analysis, fuzzy set operations, and the Dempster-Shafer Weight-ofEvidence procedure.

Since IDRISI does not provide data acquisition capabilities, import (and export) of many data formats is supported by IDRISI, including remotely sensed data (from Landsat TM, SPOT, RADARSAT, etc.), U.S. government data (e.g., USGS), desktop publishing formats (including JPEG, TIFF, BMP, GeoTIFF, etc.), and proprietary formats from ESRI, ERDAS, ERMapper, GRASS, and MapInfo. Besides the application of included tools, IDRISI enables application-oriented programming by providing an application programming interface (API). Since the IDRISI API is based on OLE/COM technology, programming can be done in all OLE/COM languages and programming environments, including Visual Basic, VB for Application, Visual C++, and so on.

The use of IDRISI is not limited to specific application domains. However, it has been used mainly in the following areas, which benefit from IDRISI's strong capabilities in analyzing and visualizing raster data:

• Urban and regional planning, including multicriteria analyses for site selections
• Management of natural resources, such as forest and hydrological resource assessments
• Environmental and ecological studies, such as land use change analysis and soil quality assessment
• Analyses of natural hazards, such as flood prediction and landslide vulnerability assessment

Since 1995, IDRISI Resource Centers (IRC) have been established worldwide by Clark Labs to promote [Page 224]IDRISI and to support its users. These centers provide training materials, IDRISI-related literature and additional documentation. User meetings are hosted by the IRCs in order to support information exchange in the application and further development of IDRISI. Currently, there are 18 IRCs established on all continents except Australia.