Extendlibur: Dynamic Haptic Retargeting for Length-Mismatched Proxies in Co-Located VR

Haptic retargeting is an effective technique to deliver realistic haptic feedback from a single physical proxy to multiple virtual objects. Previous studies have mainly focused on single-user scenarios involving virtual objects with varying shapes or locations, but few have explored how to retarget multiple virtual objects that are jointly manipulated or interacted with by multiple users. This paper presents a new haptic retargeting technique for co-located VR. It allows two users to interact using shape-mismatched virtual tools, specifically lengths that mismatch the physical props they hold. By gradually offsetting the virtual tools, the technique ensures appropriate haptic feedback and creates the illusion of using tools with different lengths. We conducted a user study to examine how much the virtual tool's length can be altered using our approach in our setup without breaking the illusion for users. Based on the findings, we proposed two example uses and validated in a follow-up application study. The results show that our method can provide more realistic and enjoyable experiences in shared VR environments.