Investigation of the Quality of Shape Definition by Hand Motions

In preceding research, the concept of the Hand Motion Language (HML) was developed as a novel and intuitive interface for Computer Aided Conceptual Design (CACD) systems. Also, a pilot implementation of the HML interpreter was developed and tested. Current research focuses on the applicability of HML in real-life situations. Firstly, this paper reports on the connection of the HML to the Vague Discrete Interval Modeler (VDIM) as an input interface. Together with the HML interpreter, it serves as a testing environment. Secondly, the paper concentrates on the design and evaluation of an experiment which was done to study the quality of shape definition by hand motions. Three quality measures were established: (i) fidelity of the generated surfaces, (ii) accuracy of the surface manipulation functions, and (iii) difficulty of modeling. Fidelity is the degree to which the representation of a shape is similar to an ideal shape. Accuracy is defined as the degree of conformity of an indicated value, such as width or angle, to an ideal value. With regards to complexity, it is interesting for us how the number of geometric HML words relates to the number of manipulative HML words that has to be issued to model a given shape. A pilot study was designed and performed to gain insight into the problems when generating surfaces by hand motions. The task given to the users was completed within a few steps; however, the quality of the surfaces has to be improved.