- Various ecological and hydrological models require estimates of the amount and spatial distribution of monthly and annual precipitation. PRISM is an analytical model that distributes point measurements of monthly, seasonal and annual precipitation to a geographic grid. In order to use this model effectively, good graphical user interfaces were needed.
The interface enables the user to run PRISM in two modes. The Cell mode and the Grid mode. The Cell mode allows the user to select the cell for which the model needs to be run. The results are presented through graphs, text and animation. The Grid mode allows the user to run the model over the entire geographic grid. This can be used to generate maps. Control files are used as inputs to the model and the interface provides extensive support for editing these files and includes error checking and tracking features.
The target audience of this interface include the casual user, the advanced user and the developer of the model. PRISM in the Cell mode and its associated features are used by casual users. Features like the Grid mode editing control files etc. are used by the more interested user. Finally several undocumented features such as addition of new parameters to the control file are targeted at the developer of the model.
Tcl/Tk. and the Tix tool kits were used to develop the interface. Tcl/tk enables rapid prototyping of interfaces and has a rich set of graphical and functional components that help in developing neat and effective interfaces.
A java prototype of the original interface was also developed. This interface is available as an applet, accessible through the web. The applet is designed to demonstrate PRISM in the Cell mode. It presents a simple interface, where the user can select regions, zoom into a specific region and select the cell at which the model needs to be run. The applet communicates with the model through a server on HTTP server and presents the results to the user in the form of graphs, text and animation. The server queues the client (applet) requests to the models, thus enabling multiple users to access the model simultaneously through this web interface.