Chapter 12 Signature Exploration, a Means to Improve Comprehension and Choice within Complex Visualization Processes: Issues and Opportunities Penny Noy, City University, London EC1V 0HB, UK Keywords: comprehension of visual depictions, dimension reduction, information maps, signature exploration Abstract All fields of visualization have, to some extent, to deal with visualizing high- dimensional data. In projecting such complex data into 2- or 3D or in the use of novel representations that allow direct mapping of greater numbers of attributes, two problems must be addressed: choice of appropriate display and understanding of the resultant graphic. At the same time, the general context is of an ever-expanding set of visualization tools available to increasingly varied types of users, so that it is becoming increasingly important to establish techniques to support user comprehension. This chapter provides some thoughts on this subject and outlines a proposed concept to provide a framework for developing techniques to support user choice and under- standing in visualizations of complex data – signature exploration. Some example software has been developed that illustrates the techniques. Signature exploration involves the use of specially constructed datasets that are known in some sense by the user. The datasets are used to explore the signatures of different visual representations and mathematical transformations. The chapter defines and illustrates signature exploration, together with five proposed techniques for the use of constructed data: generic dataset provision; user-construction of data; querying; insertion of landmarks; elicitation and application of feedback data. Two new interaction forms are described: brushing between data table and representation; synthetic additions to real-world datasets to provide the user with calibration of the visual depiction. Whilst each of these techniques needs further empirical evaluation, this overview provides sufficient description for developers to incorporate specific aspects easily. Thus the chapter is a general discussion of relevant issues and the suggestion of some specific techniques for increasing comprehension of visualization systems. Exploring Geovisualization J. Dykes, A.M. MacEachren, M.-J. Kraak (Editors) q 2005 Elsevier Ltd. All rights reserved. 243 preprint : November 2004 - do not redistribute. J. Dykes, A.M. MacEachren, M-J. Kraak (2005), Exploring Geovisualization, Pergamon, 732pp. 0-08-044531-4