Redirected Drawing: Expanding the Perceived Canvas Size in VR

Drawing, writing, and painting on 2D surfaces in VR offers arbitrary interaction with virtual canvases of unlimited size. However, this advantage has not been fully exploited because physical surfaces are needed to support accurate and comfortable user interactions, and the size of such surfaces is limited. We propose Redirected Drawing, a novel methodology that applies visual manipulation to the user’s drawing movement in VR to expand the perceived surface size required for the drawing experience. To this end, this study specifically explores translation gain manipulation, where the displacement of a drawing stroke in reality is simply multiplied by a gain to represent it in VR. We conducted a user study (N = 18) to measure the noticeability, acceptability, and task performance of a simple VR line-tracing task under different gain and input methods (i.e., finger in mid-air, finger on surface, pen on surface). Our results show that pen-based drawing on a physical surface allows for a gain of up to 1.16 without being noticed by the user, which is more suited to expanding a virtual canvas size than finger-based drawing on a physical surface or in mid-air. Furthermore, we show that user acceptability of the gain manipulation could be estimated by a model using the subjective discrepancy caused by the gain. Results for this model suggest that users could accept gains of up to 1.30. Based on our results, we derive guidelines for the effective use of gain manipulation.