Special issue of selected papers from visualization and data analysis 2011.

This document is an editorial introduction to a special issue of selected papers from the 18th SPIE Conference on Visualization and Data Analysis (VDA 2011). The conference is a major international forum for researchers and practitioners interested in data visualization and analytics research, development, and applications. The special issue features five papers that were selected as the best from the conference. The papers cover topics such as visualizing explicit and implicit relations of complex information spaces, web-enabled visualization for geovisual analytics, visualization of scattered moment tensors, interactive isosurfaces with quadratic C1 splines, and visual exploration of frequent patterns in multivariate time series. The authors express their gratitude to the contributors, reviewers, and program committee for their valuable contributions. [Extracted from the article]