Focus+Context previous work combine overview and detail into single view Focus+Context large tree browsing Cone Trees [Robertson et al 91] Hyperbolic Trees [Lamping et al 95, Munzner 97] Space Tree [Plaisant et al 03] DOI Tree [Card and Nation 02] global Document Lens [Robertson and Mackinlay 93] Rubber Sheets [Sarker et al 93] our contribution scalability, guaranteed visibility 37