Usability testing of a web-based 3D Cadastral visualization system

Many countries are extending their cadastral visualization systems in the third dimension. The reason for this stems from the increasing complexity of contemporary cities, the growing 3D approach in other fields (including 3D spatial data acquisition, spatial data processing and visualization), which made 3D cadastre technologically feasible, and the need to overcome the issues of 2D visualization. The visualization of cadastral parcels in 3D is a challenge, since legal boundaries are, in many cases, invisible in the real world; so how can we properly represent something that is not visible to our eyes? This paper results from research that looks into problems of occlusion and ambiguous perception (in terms of position, size and shape) of objects in the context of 3D cadastre visualization. The exploration of specific interaction techniques is essential to overcome these issues.
The aim of this paper is to provide ’lessons learned’ resulting from the implementation of a 3D cadastre prototype that was built with the specific goal of trying out several visualization options of 3D cadastral information in a web environment. A usability test was carried out to obtain feedback from different groups of users. Usability is meant in terms of effectiveness and efficiency of the system and users’ satisfaction. The test users were subdivided into groups according to different professional domains and expertise. During the test, the users are asked to perform a series of tasks typical of cadastral systems. Each task is accompanied by a description to give the users some context. Then, each user is asked to answer a questionnaire about his or her experience. The results are used to extract general feedback. The outcome of the usability test is crucial to point out the detected limitations in this early stage of the prototype development. Design changes can then be made according to the feedback of the test users.