In order to make the LUCAS interface more easily maintainable, the proprietary Motif User Interface Language (UIL) was used to define the widgets used in the interface. Originally, the interface was written solely in C [9] which became too cumbersome and complex to easily alter the look and feel of the interface. UIL is a high-level, almost script-like language which is rapidly compiled into a binary format. All of the widget callback and support routines must be written in C and linked to the UIL code. An additional .uid file must be present in the directory with the executable to use the UIL-compiled code. UIL does not allow as much flexibility as raw C code, but it also does not require as much programming to create and maintain a simple interface such as the one used in LUCAS.
Figure 5: LUCAS graphical user interface with sample beginning
and ending land-cover maps for a simulation run along with
graph of output summary statistics.