Multimodal Vision–Haptic Perception of Digital Watermarks Embedded in 3-D Meshes

In this paper, a study is conducted to investigate the role of multisensory feedback in the perception of a watermark embedded in a haptic-enabled 3-D virtual surface. Specifically, we focus on whether the use of a bimodal approach, where a subject is looking at, and touching a 3-D mesh could in fact improve the perceptibility of a watermark as opposed to when only a single modality (vision-alone or haptic-alone) is available. The experiments are performed using a vision-haptic interface that enables users to see and touch virtual objects at the same location in space. This approach enables superior integration of vision and touch than a conventional 2-D screen-based display. An analysis of variance (ANOVA) is also conducted to statistically explore the impact of the considered modalities (vision, haptic, and vision-haptic) on the measured watermark detection thresholds across different resolutions of the underlying virtual 3-D mesh. Overall, the results suggest that relying on bimodal vision-haptic feedback is better than any of the single modalities when detecting a watermark embedded in a 3-D model. In addition, it has been assessed that the impact of the selected modality on the perceptibility of the 3-D watermark is independent of the chosen surface resolution.