Human-computer interaction with geologic maps

2. Human-computer interaction with geologic maps

A geologic map set is composed of several the- matic maps, which are made for different purposes Že.g., geologic structure map, hydrogeologic map and . soil map . These data can be combined in an hyper- medial organisation. Depending on the objective of the study, this is done in different ways. Converting geologic paper maps into digital maps offers new possibilities for the representation of the underlying model. On the one hand, it enables the analytical process of geologic mapping, where the Ž . model and with it the geologic map may change Ž dramatically if new data become available Nickless . and Jackson, 1994 . On the other hand, geologic maps are used for different purposes depending on the specialisation of the user. These two points show the needs for efficient Ž . database support see Section 4 . However, the best database is useless if it does not provide the end user with an easy-to-use interface to the available infor- mation. A common way to obtain an appropriate interface is to conduct interviews with specialists Ž . Linton et al., 1989 . Hence, we asked geologists Ž from different disciplines e.g., hydrogeologists, re- search geologists, soil scientists and structure geolo- . gists about their specific way of working and their wishes for the interaction with digital geologic maps. The following points emerged clearly from the inter- views. Ø The need to design tools that handle geologic hypermaps was confirmed. The geologists wanted to interact with digital maps in the same uncomplicated way they do with hypertexts. They requested to be guided through the system and retrieve all the avail- able information by clicking the mouse. Ø Depending on the specialisation, each geologist needed different data and tools to handle them. He or she did not want to waste time by searching the entire set of information. It would be desirable to immediately retrieve a user-specific data selection. Ø In the explanatory text of traditional geologic maps, it is difficult to follow the author’s steps of work leading to the resulting map. Due to technical limitations, only the final results of the interpreta- tions are plotted and many of the true features of the map are lost, e.g., the uncertainty of borders between geologic units or the hypothetical nature of indicated geologic objects. This study showed that, according to the level of specialisation of the geologist, different data and methods for interpretation have to be provided. For the development of the user interface, a flexible expert solution is adopted, where the layouts are Ž fixed by the dialogue author Wetzenstein- . Ollenschlager and Wandke, 1990 . To implement a ¨ first prototype, we selected the GIS development Ž environment ArcView 3.0 Environmental Systems . Research Institute, 1998 . This system offers a graphical user interface which can be expanded by user-defined methods. Additionally, the layer-ori- ented concept of a GIS database has the advantage that the graphical data can be stored and displayed as desired allowing separate layers to be related to each other in different ways. A hypermedial map set was built which can be used in a straightforward manner. If the user selects Ž . one part of the map region query , he or she re- ceives a pull-down menu, which offers a choice of background information and interpretation methods. In addition, the user is guided through the system by a number of dialogue boxes. The prototype has been evaluated by various test users during the development phase. The results were used to improve the user-friendliness of the Ž prototype, which is of prime importance Khoshafian . et al., 1992; Carey, 1994 . The hypermedial structure of our prototype is described in detail in Kubler et al. ¨ Ž . 1998 . We focus here on the background ideas of our project and the experiences and insights we gained in its development.

3. User-specific tools