Application of the Simplified HMD-Based VR System to Road Design Process Koji Makanae 1 Hirofumi Matsuda 2 1) Ph.D. Prof., School of Project Design, Miyagi University, Kurokawa-gun, Miyagi, Japan. Email: makanae@myu.ac.jp 2) M. Proj.Des, Trion Corporation, 47-1 Kanda Higashimatsushita-cho, Chiyoda-ku, Tokyo, Email: h_matsuda@trion.co.jp Abstract: In road design, it is necessary to accurately grasp the three-dimensional (3D) terrain features; virtual reality (VR) technologies can in this regard. In this paper, we present our road design system using a simplified head-mounted display (HMD) and a USB stick controller, which a designer can use to draw road lines based on control points. To evaluate the utility of the system, comparison experiments with contour diagrams and CG systems are conducted, showing that the system effectively understands the topography and the 3D shape of the planned road. However, fatigue and sickness were observed in subjects, owing to the weight of simplified HMD and VR-related nausea, respectively. In the future, a multi-user environment will be considered. Keywords: Virtual reality; Simplified HMD; Roadway design; Digital terrain model. 1. INTRODUCTION Grasping three-dimensional (3D) topography and drawing a harmonious highway route is the most important factor in mountain-area road design. Contour maps have long been used as base maps for understanding topography. However, recent 3D computer graphics advances have enabled us to leverage topography without paper contour maps. Thus, we have been studying design methods in virtual spaces that can more accurately reproduce 3D topography. Expensive equipment, however, including head-mounted displays (HMD), is required. In recent years, simplified smartphone-based HMDs have become very popular. Virtual reality (VR) environments have thus been created, where anyone can easily enjoy an advanced VR experience anywhere. With the advance of game systems, VR has also rapidly improved. These systems make it possible to easily design a virtual space without depending on expensive or specialized equipment. Therefore, we offer a road design system based on a simplified cardboard smartphone HMD with lenses to solve the current problems of road design. 2. ROAD DESIGN METHOD IN VIRTUAL SPACE As 3D computer graphics and VR technologies have progressed, researchers have studied the applications of VR support in architecture, engineering, and construction design. For example, Whyte et al. (1999) proposed an integrated computer-aided design (CAD) VR environment using VR modeling language (VRML). Recently, utilization of VR technology for visualization simulation at the construction stage has made headway (e.g., Nashwan et al., 2010). In recent years, 3D CAD systems for infrastructure have also become popular. They can design and build a practical 3D structure based on a planned roadway (e.g., Knag et al., 2017). However, few studies have been attempted that design directly in the 3D virtual space. We envision a system that a designer can use to draw a roadway route using parametric curves in a virtual, stereoscopic space constructed from aerial photographs. Although aerial photographs have always been useful to road designers, matching them with a 3D terrain model has been difficult in real time. In response to this problem, we present a VR-CAD system that can build and arrange road structures, buildings, trees, etc., on a virtual terrain model using an HMD. We also present a model that expresses 3D road geometry built on a curvature and gradient function, based on road length. The terrain surface expressed in the virtual space is expanded into physical space using a tangible terrain display controlled by 64 stepping motors. Our route planning system is developed on this framework. With this system, we show that 3D design in a virtual space is possible without using topographic maps. However, the use of HMDs is inevitable.