Catálogo de publicaciones - libros

This paper describes an algorithm for generating a figure in a two-dimensional plane from a qualitative spatial representation of PLCA. In general, it is difficult to generate a figure from qualitative spatial representations, since they contain positional relationships but do not hold quantitative information such as position and size. Therefore, an algorithm is required to determine the coordinates of the objects while preserving the positional relationships. Moreover, it is more desirable that the resulting figure meets a user’s requirement. PLCA is a simple symbolic representation consisting of points, lines, circuits and areas. We have already proposed one algorithm for drawing, but the resulting figures are far from a “good” one. In that algorithm, we generate the graph corresponding to a given PLCA expression, decompose it into connected subgraphs, determine the coordinates in a unit circle for each subgraph independently, and finally determine the position and size of each subgraph by locating the circles in appropriate positions. This paper aims at generating a “good” figure for a PLCA expression. We use a genetic algorithm to determine the locations and the sizes of circles in the last step of the algorithm. We have succeeded in producing a figure in which objects are drawn as large as possible, with complex parts larger than others. This problem is considered to be a type of “circle packing,” and the method proposed here is applicable to the other problems in which locating objects in a non-convex polygon.

This paper discusses the conceptualization of turn directions along traveled routes. Foremost, we are interested in the influence that language has on the conceptualization of turn directions. Two experiments are presented that contrast the way people group turns into similarity classes when they expect to verbally label the turns, as compared to when they do not. We are particularly interested in the role that major axes such as the perpendicular left and right axis play—are they boundaries of sectors or central prototypes, or do they have two functions: boundary and prototype? Our results support a) findings that linguistic and nonlinguistic categorization differ and b) that prototypes in linguistic tasks serve additionally as boundaries in nonlinguistic tasks, i.e. they fulfill a double function. We conclude by discussing implications for cognitive models of learning environmental layouts and for route-instruction systems in different modalities.

Landmarks are crucial for human wayfinding. Their integration in wayfinding assistance systems is essential for generating cognitively ergonomic route directions. I present an approach to automatically determining references to different types of landmarks. This approach exploits the circular order of a decision point’s branches. It allows uniformly handling point landmarks as well as linear and areal landmarks; these may be functionally relevant for a single decision point or a sequence of decision points. The approach is simple, yet powerful and can handle different spatial situations. It is an integral part of , a process generating context-specific route directions that adapts wayfinding instructions to a route’s properties and environmental characteristics. accounts for cognitive principles of good route directions; the resulting route directions reflect people’s conceptualization of route information.

Previous work is reviewed and an experiment described to examine the spatial and strategic cognitive factors impacting on human orientation in the ‘drop-off’ static orientation scenario, where a person is matching a scene to a map to establish directional correspondence. The relative roles of salient landmarks and scene content and geometry, including space syntax isovist measures, are explored both in terms of general effects, individual differences between participant strategies, and the apparent cognitive processes involved. In general people tend to be distracted by salient 3D landmarks even when they know these will not be detectable on the map, but benefit from a salient 2D landmark whose geometry is present in both images. However, cluster analysis demonstrated clear variations in strategy and in the relative roles of the geometry and content of the scene. Results are discussed in the context of improving future geographic information content.

Data quality and ontology are two of the dominating research topics in GIS, influencing many others. Research so far investigated them in isolation. Ontology is concerned with perfect knowledge of the world and ignores so far imperfections in our knowledge. An ontology for imperfect knowledge leads to a consistent classification of imperfections of data (i.e., data quality), and a formalizable description of the influence of data quality on decisions. If we want to deal with data quality with ontological methods, then reality and the information model stored in the GIS must be represented in the same model. This allows to use closed loops semantics to define “fitness for use” as leading to correct, executable decisions. The approach covers knowledge of physical reality as well as personal (subjective) and social constructions. It lists systematically influences leading to imperfections in data in logical succession.

The concept of the categorical gradient field is introduced to encompass spatially continuous fields of probabilities or membership values in a fixed number of categories. Three models for implementing categorical gradient fields are examined: raster grids, epsilon bands and gradient polygons. Of these, the gradient polygon model shows promise but has not been fully specified. A specification of the model is developed via a four-step process: 1) the constrained Delaunay triangulation of the polygon is created, 2) vertices are added to the polygon edge to ensure consistency, 3) a skeleton of the medial axis is produced and flat spurs are identified, and 4) additional vertices are added along each flat spur. The method is illustrated on a hypothetical transition zone between four adjacent regions, and evaluated according to five general criteria. The model is efficient in terms of data storage, moderately flexible and robust, and intuitive to build and visualize.

Rough sets have been applied in spatial information theory to construct theories of granularity – presenting information at different levels of detail. Mathematical morphology can also be seen as a framework for granularity, and the question of how rough sets relate to mathematical morphology has been raised by Bloch. This paper shows how by developing mathematical morphology in terms of relations we obtain a framework which includes the basic constructions of rough set theory as a special case. The extension of the relational framework to mathematical morphology on graphs rather than sets is explored and new operations of dilations and erosions on graphs are obtained.