USE OF DEPTH CUES FOR THE ANNOTATION OF 3D CARTOGRAPHIC ENVIRONMENTS
S. Maass1, M. Jobst2, J. Doellner1
1 - University of Potsdam, Research Group 3D Geoinformation, Potsdam, Germany
2 - Technical University of Vienna, Research Group Cartography, Vienna, Austria
(1) Digital cartographic presentations make use of interactivity, animation, and multimodality to support the spatial information transfer as well as to overcome restrictions of digital interfaces.
(2) General cartographic restrictions result from limited interface resolution and extension. These restrictions do have massive impact with non-interactive information transfer of spatial map-element relations in the case of 3D cartographic information. A small interface extend even for 2D presentations, e.g., displays of mobile devices, reduce the possibility to communicate spatial relations. On one hand, the map elements are hardly perceivable in a small scale, when relations of many elements should be visible. On the other hand, if only a subset of relations is displayed then the symbols can be easily read in a large scale.
(3) 3D cartography, which can combine various scales in one single view, possibly forms one solution to overcome restrictions of 2D presentations on small displays (examples can be given with actual navigation systems and their use of “3D”). Further advantages can be argued with an intuitive transmission of spatial relations, whereas psychological depth cues, especially on Pseudo3D interfaces, play an important role for the process of recognition. As disadvantages, the damage of depth cues causes misleading information transfer and, in most cases, makes intuitive perception impossible. In case of annotations in 3D cartographic presentations various cases of disturbed psychological depth cues may occur and call for specific solutions. A classification of these cases may show up applicability and dependencies within the cartographic 3D environment.
(4) This contribution presents first results on how to improve information transfer of 3D cartographic environments. Evaluating existing implementations, we found that automated 2D annotation techniques used in traditional map presentations cab disturb depth cues if natively applied to 3D cartographic environments. This implies that apart from readability, visibility, and quality of assignment, the perceivable perspective disturbance additionally influences the quality of labeling techniques in 3D cartographic environments. In this contribution we describe possible disturbance through the damage of linear perspective through annotation. We illustrate this effect by examples, identify possible solutions, specify adaptable cases, and report our results in the creation of user tests in order to support the statements posed. Finally, we discuss the impact of our results on the design of automatic label placement strategies in the future.
1. The role of 3D for cartographic information transmission.
2. Existing problems in cases of annotations in 3D presentations.
3. Adapted semiotic in order to keep readability, visibility and ability of allocation.
4. The opposition of supporting depth cues versus enabling perception.
5. Resulting “solving” cases.
6. Further work, the prove with user testing.