Visualizing perceived spatial data quality of 3D objects within virtual globes

Virtual globes (VGs) allow Internet users to view geographic data of heterogeneous quality created by other users. This article presents a new approach for collecting and visualizing information about the perceived quality of 3D data in VGs. It aims at improving users' awareness of the quality of 3D objects. Instead of relying on the existing metadata or on formal accuracy assessments that are often impossible in practice, we propose a crowd-sourced quality recommender system based on the five-star visualization method successful in other types of Web applications. Four alternative five-star visualizations were implemented in a Google Earth-based prototype and tested through a formal user evaluation. These tests helped identifying the most effective method for a 3D environment. Results indicate that while most websites use a visualization approach that shows a ‘number of stars’, this method was the least preferred by participants. Instead, participants ranked the ‘number within a star’ method highest as it allowed reducing the visual clutter in urban settings, suggesting that 3D environments such as VGs require different design approaches than 2D or non-geographic applications. Results also confirmed that expert and non-expert users in geographic data share similar preferences for the most and least preferred visualization methods.