When scientific data sets can be interpreted visually they are typically managed as pictures and consequently stored as large collections of bitmaps. Valuable information contained in images is often not exploited, however simply because the data is not processed further. Common reasons for this are that access to information in image collections is notoriously difficult and that interesting applications often depend on supplementary data with incompatible formats. If such data sets are treated as higher-dimensional point data instead of byte streams and managed with a suitable multidimensional file structure, then it is possible to transform "fuzzy" objects into n-dimensional solids. Several benefits result: content based access becomes possible, the potential for data compression without loss of relevant information exists and additional information can readily be incorporated simply by increasing the file structure's dimensionality. This paper describes how this approach has been successfully applied to detect and track storm cells in weather radar and various satellite images. The key is to parametrize the data for efficient access based on several different image attributes.

Earth scientists, by definition, work in an interdisciplinary environment and therefore collect and disseminate data using distinct methods, depending on whether the associated information arises during field measurements, arrives via remote sensing, or represents simulation results. When calculating the global radiation over one of the oceans, for instance, it is essential that cloud data from at least three different sources can be accessed based on one and the same geographic grid. Differently gridded source data must therefore be reorganized through interpolation for example. This can be done in different ways and we investigate a method whose practicality depends on fast spatial range queries, but in turn provides a flexibility that makes it particularly easy to accommodate differently organized data sets-a valuable feature when unanticipated grid organizations show up.>

To extend the scope of multivariate data visualization, the notion of comparative visualization is introduced: it allows the comparison of visualization methods by interconnecting several different graphic displays. This linking of visualizations, together with the possibility to interactively manipulate data, enable an analyst to display the same data set with a number of conceptually different visualization methods simultaneously and to carry out graphical operations across them. Graphical effects in different displays not only reveal information about the data themselves, they also provide the basis to investigate how the different visualization methods relate to each other. With the "VisuLab", we developed a software tool for personal computers to investigate comparative multivariate data visualization.>

The paper provides a review of the field of multidimensional data visualisation and discusses some promising methodologies. It considers some crucial problems and directions. The emphasis is more on concepts and foundations rather than ad hoc methods. Visualization is considered as a collection of transformations from problem domains to a perceptual domain, usually visual. The paper discusses the extension of visualisation from the pixel to icons.>

Traditional file structures that provide multikey access to records, for example, inverted files, are extensions of file structures originally designed for single-key access. They manifest various deficiencies in particular for multikey access to highly dynamic files. We study the dynamic aspects of file structures that treat all keys symmetrically, that is, file structures which avoid the distinction between primary and secondary keys. We start from a bitmap approach and treat the problem of file design as one of data compression of a large sparse matrix. This leads to the notions of a grid partition of the search space and of a grid directory , which are the keys to a dynamic file structure called the grid file . This file system adapts gracefully to its contents under insertions and deletions, and thus achieves an upper bound of two disk accesses for single record retrieval; it also handles range queries and partially specified queries efficiently. We discuss in detail the design decisions that led to the grid file, present simulation results of its behavior, and compare it to other multikey access file structures.