¹Dipartimento di Informatica e Sistemistica, Università di Roma, Rome, Italy

Correspondence: Enrico Bertini, Università di Roma "La Sapienza" Via Salaria, 113, 00198 Rome, Italy. Tel: +39 06 49918339; Fax: +39 06 85300849; bertini@dis.uniroma1.it

Received 28 February 2005; Revised 28 December 2005; Accepted 20 February 2006; Published online 2 June 2006.

Abstract

The problem of visualizing huge amounts of data is well known in information visualization. Dealing with a large number of items forces almost any kind of Infovis technique to reveal its limits in terms of expressivity and scalability. In this paper we focus on 2D scatter plots, proposing a 'feature preservation' approach, based on the idea of modeling the visualization in a virtual space in order to analyze its features (e.g., absolute density, relative density, etc.). In this way we provide a formal framework to measure the visual overlapping, obtaining precise quality metrics about the visualization degradation and devising automatic sampling strategies able to improve the overall image quality. Metrics and algorithms have been improved through suitable user studies.