br Introduction In the spatial design fields such

Introduction In the spatial design fields such as architectural design and urban design, a consensus-building process among a variety of stakeholders like project executors, architects, residents, users, and general citizens is required (Innes, 1996). Since it nmda receptor is oftentimes necessary to share three-dimensional (3D) images to study spatial design, 3D Computer Graphics (3DCG), Virtual Reality (VR) and Building Information Modelling (BIM) systems have been developed. Spatial design meetings using these systems have been traditionally held in a single room and at a certain scheduled time. However in recent years, the mobility of people׳s activities and cloud computing technologies have advanced in the modern age of information and globalization. Therefore, Virtual Design Studios (VDS) have been constructed by numerous universities and institutions across the world exploiting new computing and communication technologies (Wojtowicz, 1994; Maher and Simoff, 1999; Kvan, 2000; Matsumoto et al., 2006). Mostly, VDS system developments and design trials of an asynchronous distributed type are used allowing stakeholders to participate in the design process at various places and at different times. This enables expansion of communication opportunities, without a participant needing to be concerned about restrictions of space and time. As a result from previous approaches, which are presented in Section 2, we defined the following research questions for our work: This paper is structured as follows: Section 1 introduces the main focus on synchronous distributed VR meetings. Section 2 describes previous studies and the state of the art. Section 3 illustrates the VR system with a particular focus on the two main functions – annotation and discussion. Section 4 presents the validation of the prototype system by an empirical study. A new distributed meeting with an architect was held by applying the cloud-VR system. An initial design according to a project and the prototype system has been validated in the course of an architectural and urban design process. Finally, Section 5 lays out the conclusions and future work.
State of the art In a synchronous distributed environment, different research efforts on design supporting a system for sharing 3D virtual space have been carried out, but show a number of shortcomings. First, there is a system which allows designers to be physically immersed in their sketches and physical models, literally inside life-size, real-time representations of these, while sharing them remotely with another system of the same sort (Dorta et al., 2011). However, sketches on digital whiteboards retain well-known scale problems from sketches on paper, and oxytocin do not permit several stakeholders participating in a meeting by using a standard PC. Safin and Leclercq (2009) evaluate the opportunities and constraints linked to the technological transfer of a sketch-based distant collaborative environment. This prototype required a large electronic table with projection system. Darses et al. (2008) describe a research project which aims at studying the value of a freehand design environment for architects. This sketch-based modelling software is implemented on a Tablet PC, which provides architects with the possibility to automatically generate 3D views from the freehand drawings. However, this study has poor drawn 3D external representations, which do not fit to the level of abstraction required for handling mental volumetric representations which are cognitively processed by the designers. On one hand, Gu et al. (2009) and Shen and Kawakami (2010) developed a visualization tool on a multi-user platform to represent design alternatives and to supplement traditional presentation materials. These studies also pointed out that audio devices and web cameras are well-suited for online deliberation. Moreover, the data volume of the content of a design study is usually large. Therefore, when drawing 3D graphics using a client PC, a computer with a high-performance Graphics Processing Unit (GPU) is always required. Architect and urban design require the high-speed simulation and reconstruction in order to avoid an interruption during a synchronous distributed meeting (Al Maashri et al., 2009). A high-performance GPU had been initially used to accelerate the work of texture mapping and rendering polygons, later added units to accelerate geometric calculations to support computers in image processing, 3D reconstruction and large-scale modelling. However, high latency and cost are the major constraints to performance enhancement. Fukuda et al. (2012), on the other hand, present a first approach towards a distributed design meeting system. It allows stakeholders to participate in the design process at different places and at the same time while sharing a 3D virtual space. However, the user is not able to add sketches, figures or memos during a meeting.