Supporting the understanding of architectural interiors with non-photorealistic rendering in virtual reality

Abstract

Understanding the extent to which, and conditions under which, scene detail affects spatial understanding and perception accuracy can inform responsible use of 3D concept drawings, like sketch-like rendering styles, in applications such as immersive architectural design and walkthroughs. Using line drawing non-photorealistic rendering (NPR) has the potential to speed the design process and reduce development cost when scene details are not available yet in early stages, or to increase client participation by directing and guiding their attention to fundamental elements like ceiling height or corridor width. NPR also has the potential to reduce cybersickness in architectural walkthroughs during continuous locomotion, when fully rendered and highly detailed scenes may be disorienting, and possibly to increase spatial awareness vs. discrete teleportation. Unfortunately, egocentric distances inside a head-mounted display (HMD) have historically been found to be underestimated and appear shorter in virtual models than in the real-life counterparts. While some prior research has shown that reducing the quality of computer graphics does not significantly worsen the situation, others have found that breaking the illusion of reality can negatively impact distance perception and accuracy, and adversely affect spatial understanding. In addition, most architectural models are large-scale environments that exceed the available tracked area in VR setups. Current practice is to use either teleportation (jumping) or continuous locomotion (steering) to travel to destinations beyond reach. However, continuous locomotion is known to induce cybersickness, and discrete teleportation is famous for causing spatial disorientation. To address these issues, the results of several experiments are presented to incrementally provide important new insights into the question of the extent to which line drawing NPR rendering can be effectively used in the virtual architectural design process and VR walkthroughs, to support spatial understanding in the absence of textural detail and to lower cybersicknesss during continuous locomotion by only preserving important architectural features and scene details, while the insignificant high frequency details that cause the underlying problems are masked out. Additionally, a new proposed line drawing NPR transition method is presented to simultaneously support spatial awareness and mitigate cybersickness during a guided tour of a large architectural model.