# A Waist-Mounted Interface for Mobile Viewpoint-Height Transformation Affecting Spatial Perception

## TL;DR

A waist-mounted camera and display system changes how people perceive space and their body position, influencing their confidence and movement when navigating gaps.

## Contribution

A novel waist-mounted interface that transforms viewpoint height in real time to affect spatial perception and body representation.

## Key findings

- Confidence in passing through a middle-height gap decreased with a head-level viewpoint and increased with a waist-level viewpoint.
- Walking speed decreased when a waist-level viewpoint was combined with a chest-height gap, indicating increased caution.
- Participants reported a lowered head position relative to the torso, suggesting visually driven rescaling of body image.

## Abstract

Visual information shapes spatial perception and body representation in human augmentation. However, the perceptual consequences of viewpoint-height changes produced by sensor–display geometry are not well understood. To address this gap, we developed an interface that maps a waist-mounted stereo fisheye camera to an eye-level viewpoint on a head-mounted display in real time. Geometric and timing calibration kept latency low enough to preserve a sense of agency and enable stable untethered walking. In a within-subject study comparing head- and waist-level viewpoints, participants approached adjustable gaps, rated passability confidence (1–7), and attempted passage when confident. We also recorded walking speed and assessed post-task body representation using a questionnaire. High gaps were judged passable and low gaps were not, irrespective of viewpoint. At the middle gap, confidence decreased with a head-level viewpoint and increased with a waist-level viewpoint, and walking speed decreased when a waist-level viewpoint was combined with a chest-height gap, consistent with added caution near the decision boundary. Body image reports most often indicated a lowered head position relative to the torso, consistent with visually driven rescaling rather than morphological change. These findings show that a waist-mounted interface for mobile viewpoint-height transformation can reliably shift spatial perception.