## 2 Theoretical Framework for Assessing Virtual Globes
### Virtual Globes as Participatory Landscape Visualization Platforms: Benefits and Limitations
When \"zoomed in\", virtual globes allow the viewers to position themselves in an immersive eye-level view on the ground, but in most cases, the realism appears to be lower than it is in the elevated oblique \"landscape\" view. Consequently, Google covers the foreground scenes with its complementary service StreetView for select built-up areas. It is still an open question how much cognitive load these diverse landscape impressions impose on the user and how different user groups can cope with that cognitive load [20, 21]. [PERSON] [22] earlier defined accuracy, representativeness, visual clarity, interest, legitimacy, access to visual information, framing, and presentation as crucial criteria for the ethical use of landscape visualizations in general. [PERSON] and [PERSON] [1] published the first critical discussion of virtual globes for landscape related disciplines. They focused on key issues such as landscape perception that moves beyond cartography to cross a crucial threshold into experiential imagery. Such imagery can evoke more emotional and value-laden, potentially overwhelming, cognitive responses [23]. Additional 4D (time-collapsing) and animation features can increase public interest and awareness but may also add too much drama and cognitive load [17, 24]. If virtual globes are used online without face-to-face explanation or detailed written background information about underlying data and methodology, the risk of misinterpretation or bias is likely to increase [11]. Issues related to projecting future conditions are particularly relevant for this project: the field is largely technology-driven and therefore more focused on the evaluation of technical performance and realistic rendering rather than validity and reliability in a scientific sense. [PERSON] and [PERSON] [1] identify further potential risks when experts and lay people use virtual globes in planning. Issues around data and software, perceptual issues, and power implications of data ownership, expert knowledge and corporate user terms can create unsolved ethical issues if virtual globes are applied in political processes. [PERSON] [25] notes that the horizontal positional accuracy of images can be as low as +/- 60m. Despite the participatory benefits of user-generated content or Volunteered Geographic Information (VGI), the accuracy problem is aggravated through the incorporation of VGI because VGI come in a variety of scales with different levels of certainty and detail, often without documentation or metadata. Furthermore, most virtual globes lack features to document metadata or make data quality transparent to the user. If the representation appears to be more realistic than the accuracy of the underlying data allows, the resultant \"apparent realism\" can be misleading. In a multiple case study in China, [PERSON] and [PERSON] [26] document the diverse datasets from multiple disciplines that were integrated in a virtual globe, increasing the accessibility of diverse datasets across multiple disciplines. [PERSON] and [PERSON] [1] also identify potential benefits of using virtual globes in landscape planning, including increased accessibility of geospatial information, the potential for increased interest and awareness, and in contrast to static landscape visualizations, a higher representativeness of the landscape because users can choose multiple individual viewpoints (Table 1). \begin{table}
\begin{tabular}{p{142.3 pt} p{142.3 pt}} \hline \hline
1. Access to visual information & Open free access for all Internet users with high-speed connections and reasonably up-to-date computers, providing relatively equitable access to information within the “developed” world (especially across remote areas or scattered users), though probably concentrated more on those who are younger, more affluent, with more formal education, and higher levels of computer literacy [27, 28]. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Key benefits of using virtual globes to provide landscape visualizations ([PERSON] and [PERSON] 2009: 6).