Information exploration involves building bridges between document space (the realm of information artifacts, ranging from books to e-mail to bibliographic citations) and concept space (the context and knowledge required to interpret documents). This dissertation proposes an interactive, structure-mediated approach to exploring information in a heteroge- neous, distributed environment---such as a digital library. It presents a conceptual model for information exploration, a system (SenseMaker) that embodies the proposed model, and several evaluative user studies. Two principles form the crux of our structure-mediated conceptual model, which supports users in moving back and forth between document space and concept space: . Users should be able to build document-based structures for document collections by interactively organizing them around contextual dimensions (e.g., author). These higher-level structures reveal key concepts (e.g., specific authors). . Users should be able to cre...

PG RT is an environment for the integration of tools and systems for instrumentation, performance visualization, and analysis of complex real-time systems. A part of PG RT is the Visual Objects framework for rapid prototyping and development of object-oriented, online, adaptive, application-specific performance visualizations. PG RT uses CORBA technology to provide real-time applications and systems with convenient access to visual objects. Many complex visual objects may be distributed over a number of graphical workstations in a local area network to provide rich visualization in real time. The visual objects can be directly accessed from a distributed real-time application, or--- in order to eliminate the intrusion of CORBA to the application---via a distributed instrumentation system called BRISK, which is a component of PG RT . We demonstrate the PG RT environment by instrumenting and visualizing a distributed real-time multimedia application. 1 Introduction An abili...