Constraint-based bare-hand immersive 3D modelling

Three-dimensional user interfaces that are controlled by the user's bare hands are mostly based on purely gesture-based interaction techniques. However, these interfaces are often slow and error prone. Especially in the field of immersive 3D modelling, gestures are unsuitable because they complicate and delay the modelling process. To address these problems, we present a new gesture-free 3D modelling technique called "3D touch-and-drag", which allows users to select vertices by approaching them and to terminate operations by moving the 3D cursor (e.g. the forefinger) away from the constraint geometry (e.g. a straight line or a plane). Our proposed technique makes it possible to transfer the existing 3D modelling concepts ("3D widgets") to virtual environments, as shown by an experimental 3D modelling tool. The gesture-free bare-hand interaction also improves the possibility of tactile feedback during 3D manipulation. We compared different modelling techniques for controlling the 3D widgets. We found that controller-based techniques are significantly faster than finger-tracking-based techniques. The 3D touch-and-drag technique is about as fast as gesture-based interactions. Mouse interaction in a two-dimensional GUI is only slightly faster than the 3D modelling techniques. Since our proposed technique has proven to be at least equivalent to gesture-based interaction techniques in terms of accuracy and efficiency, its further development using more accurate tracking techniques seems promising to exploit the advantages of hands-free and gesture-free interaction for immersive 3D modelling. © 2023 the author(s), published by De Gruyter, Berlin/Boston.