A Simple, Portable, Spatial Multi-Criteria Analysis Shell - MCAS-S

Multi-criteria approaches to analysis of complex issues in coupled human-environment systems have found wide application across business, government and communities around the world. Increased attention has been paid to spatial implementations of multi-criteria analysis. Spatial capability is available in several GIS, such as IDRISI and ArcView, and is often customised for particular problems in spatially explicit decision tools. However, simple, flexible multi-criteria shells are not readily available, particularly without a programming requirement, and with easy adaptability to any problem. The ASSESS (A System for Selecting Suitable Sites) multi-criteria interface in ArcInfo GIS has been applied widely over a number of years - most recently in analysis of tensions in Australian rangelands. However, there is now a need for a completely portable and flexible spatial multi-criteria shell to assist in exploration of a wide range of science-policy issues at government and community level. making. This paper describes a multi-criteria analysis shell for spatial decision support (MCAS-S) constructed in C and C++. The key constructs that characterize the shell are: 1) the combination of cognitive mapping and actual map display and manipulation in the workspace window; 2) automatic association of menu panes with map types; and 3) live update of layers in the workspace when changes are made to classification of primary layers. The user can select grids, drag them into the display window, manipulate them, then create composites and do two-way comparisons forming a cognitive flow diagram of maps and arrows on the screen. Another important feature is the automatic update of available functions when the user accesses maps of different types such as raw input data, composite indicators, and two-way and multi-way comparisons. This makes the interface very intuitive to use. The shell requires basic GIS preprocessing of data to the same grid resolution, spatial extent and projection. The shell provides the following key functions: reads grid data in several formats; calculates histograms and enables grid classification in a variety of ways; provides for two-way comparisons; provides multi-way analysis of multiple grids with graphical representation as radar plots; provides for pixel interrogation using radar plot and two-way matrix graphics; allows creation of binary inclusion zones from radar plots; allows creation of scaled (0 - 1) floating point multi-way summary index using various methods of combination. The conceptual model for use of the software by policy clients and stakeholders involves: desktop access for policy makers with project constructed by consulting experts; projects distributed to clients with online participatory analysis; iterative updating and re-working of project with alternative map assessments. However, the tool enables clear visualization of the relationship between the decision, the science, other constraints and the spatial data. This paper provides a full description of the shell and gives some operational examples using data from analysis of tensions in Australia's rangelands. The paper discusses the further development and application of the shell to aid policy and community decision-making.