Affective appraisal as a requirement for 3D models; a systematic approach Joske Houtkamp Center for Content and Knowledge Engineering Institute of Information and Computing Sciences Utrecht University P.O.Box 80089, NL-3508 TB Utrecht +31302536355 joske.houtkamp@cs.uu.nl ABSTRACT Expectations of the functionality of 3D models of buildings on desktop computers are often high, but requirements used in design are generally incomplete, and insufficiently specified. One of the requirements usually omitted is that users of a model also give an affective appraisal of the building represented. The process of modeling and the display on a monitor cause modifications in the representation of the building that must be compensated by manipulations of the model to achieve a certain appraisal. It is proposed that this aspect is introduced, modeled and tested separately and systematically. A description of the use of 3D models for assessing public safety, in the project Visualisatie RandstadRail, is used as support for this approach. Keywords 3D model, affective appraisal, SMB-scale, requirements, virtual environment INTRODUCTION Many desktop applications for professional or personal use contain 3D models of buildings or spaces with buildings that represent real or imaginary environments, often called virtual environments. Examples can be found in civil engineering and architectural practice, and in applications for education, such as reconstructions of ancient monuments. 3D models are useful in combining and presenting available information in a very accessible manner. It requires mental effort, prior knowledge and experience to create a mental representation of a building from plans and drawings [11]. The resulting mental representations are incomplete, may contain mistakes and are different for each individual. Until now, research in development of 3D models has concentrated on technical and cognitive issues such as real time rendering and depth perception, often driven by the intent to make the models look “photo realistic” and make navigation as easy as possible. Expectations of these models as faithful representations of reality, and thus of a realistic experience, are generally high. The models are supposed to be suited for numerous tasks, and for a variety of users. This seems to withhold developers of new models from carefully analyzing the expectations of the functionality of models, and thus from specifying detailed and valid requirements AFFECTIVE APPRAISAL AS A REQUIREMENT An important requirement that is overlooked, is that users of a model also give an affective appraisal of the building or environment represented. Affective appraisals are judgments concerning the capacity of the appraised objects, such as buildings, to alter mood, expressed in terms such as pleasant, repulsive, attractive etc. [10]. In this paper one example of a project is discussed in which the range of tasks and users is large, expectations of participants are diffuse, and in which the affective appraisal plays a larger role than one would realized at first. ENGINEERING THE AFFECTIVE APPRAISAL The hypothesis made in this paper is that many of the important characteristics of the interior and exterior of a building that contribute to the affective appraisal are not easily or completely transferred to a computer model shown on a desktop monitor, and that it is first necessary to select carefully the essential elements of a building or space that add to a certain affective quality, and secondly perform manipulation of these elements and their representation to create the effect experienced in reality. Affective appraisal must be regarded as a distinct requirement in the modeling process. MODIFICATIONS CAUSED BY DEVELOPMENT AND DISPLAY Experiments in which real rooms, buildings or environments are compared to 3D models reveal that the appraisals of viewers in both circumstances show