User interaction in a sketch-based GIS user interface
The use of sketches and drawings in people's everyday life is complementary to spoken language and gestures. Sketching and drawing are essential when complex structured information must be exchanged among people, but these modalities play only an ancillary role in human-computer interaction of today's geographic information systems. The reason for this is that most user tasks are still strongly tied to an interaction solely based on typing and pointing. Although this approach works fine for a host of applications, it can become difficult to express even simple things as soon as complicated or more-dimensional structures must be described. A typical field of application where such problems arise frequently is querying a spatial database. The main reason for these difficulties is that traditional query methods, which employ primarily text-oriented query languages, lack the power and expressiveness necessary to describe complex spatial configurations. To improve the current situation it is important to take people's needs, preferences, and abilities into account, when new systems are designed. One way of doing so is to introduce natural modalities, such as sketching or talking.
We have analyzed the potential of sketch-based user interactions with a focus on applications in GIS. This analysis is based upon considerations and comparisons of possible user modalities, actions, and operations that are feasible for sketch-based applications. We have classified the set of possible user action into five distinct categories and demonstrated how these user action can be combined to user operations. Browsing, querying, and updating are the most frequently used user operations in a GIS and it is shown how this set of user-operations can benefit from a sketch-based user interface. We have found that sketching and talking can significantly improve the usability and intuitiveness of a GIS and that these intuitive modalities are very valuable tools for generalization, interpretation, or visualization purposes of complex spatial, conceptual, or hierarchical scenarios, when these structures cannot sufficiently be described by other means.