Academic journal article Cartography & Geographic Information Systems

On Tightly Coupling Models with Visualizations: The Package for Analysis and Visualization of Environmental Data

Academic journal article Cartography & Geographic Information Systems

On Tightly Coupling Models with Visualizations: The Package for Analysis and Visualization of Environmental Data

Article excerpt

ABSTRACT. Environmental modeling activities can tremendously benefit from geographic information system (GIS) technology. Through integration of environmental models with GIS functionalities, modelers can address complex environmental issues and analyze results in an efficient and effective manner. Integrating environmental models with GIS functionalities is conceivable through either a loosely or tightly coupled approach. With current GIS technology, tight coupling, though highly desired, is impeded, leaving modelers with no option but to take a loosely coupled approach. We suggest that until such time that GIS technology allows tight coupling, the option is used of tightly coupling environmental models with specific GIS capabilities such as cartographic and visualization functionalities. We describe in this paper the need to advance tools to tightly couple models with visualization functionalities, and give an example of such tools as the Package for Analysis and Visualization of Environmental data (PAVE), which is a flexible and distributed environment to analyze and visualize multivariate gridded environmental data sets.


Geographic information system (GIS) technology has been employed as a base for developing environmental modeling applications. It is becoming an integral component of environmental modeling, because environmental modeling depends heavily on analysis of spatial data, and because GIS supports such capabilities as spatial data management, analysis, and cartographic functions. The four main components of a GIS--database management, visualization, data layering, and spatial analysis--can offer numerous benefits to environmental modeling. However, due to several technical shortcomings, often modelers can effectively utilize only the database management and visualization aspects of a GIS.

In general, regardless of the specific components employed, there are two approaches--loose coupling and tight coupling (Stuart and Stocks 1993; Batty and Xie 1994; Karimi and Houston 1997)--for integrating environmental models with GIS. The main difference between these two integration strategies is that with the loose-coupling approach, each modeling activity usually takes place in a separate environment or system, causing the frequent transfer of data from one environment to another. The tight-coupling approach, on the other hand, allows models to be developed inside GIS, or GIS within models, using the same environment to solve all problems of a specific application. For environmental modeling, tight coupling of models with GIS provides the desired solutions in an optimal manner, because environmental data are derived from many diverse sources and are very large, and the activities in environmental modeling are typically complex. This notwithstanding, current GIS technologies impede tight coupling of environmental models with GIS functionalities. Certain improvements of GIS technology are under way, which should help to overcome this problem (e.g., see Karimi 1997). However, until such time that these improvements become available, modelers have to rely on partial solutions provided by current GIS technologies. Of these alternative partial solutions, visualization tools are central to environmental modeling and are the focus of this paper.

Scientific visualization is an important and desired component of environmental modeling. Environmental modelers depend on visualization tools to make maps and to analyze the models' results. Today's GIS visualizations provide capabilities ranging from making simple statistical plots to providing complex cartographic results. All these visualization capabilities are needed in environmental modeling. Without GIS, modelers would have to turn to multiple software packages and the different solutions these offer.

Environmental modelers often rely on high-end data flow visualization environments. Advanced Visual Systems Inc.'s Application Visualization System (AVS) (Upson et al. …

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