3-D shapes out of 2-D freehand sketches: Creative spatial interpretation of sketches

For a long time, there is a demand to define the creative human problem solving in the conceptual design which is based on traditional tools like freehand paper sketches as an integrated task of the product development. The vague and fuzzy product data depicted in these freehand sketches are used for the creative search for ideas and moreover have to be used in computer-aided (CAx) environments. Until now, it is not possible to work simultaneously with both the freehand sketches and the CAx product models. This paper reports on our R&D work to interpret fuzzy shape descriptions in freehand sketches and to transfer them into digital shape models. The idea is to analyze the conceptual shape information within the sketches, to create digital two-dimensional (2-D) fuzzy shape descriptions and to define shape areas which can be deformed to three-dimensional (3-D) shape elements. The paper presents the implemented methods which apply image processing technologies to interpret the characteristics of conceptual sketches. Future work will enhance the developed 3-D data model to enable the integration of further product data like materials