# Using Mixed Reality (MR) to Improve On-Site Design Experience in Community Planning
## 1 Introduction  
With the gradual fading of urban growth supremacism, community planning that focuses on optimizing urban stock assets has stepped onto the stage of history [1]. Compared to traditional urban planning and design, focusing on new areas of development, community planning has to confront the limitations originating from existing environments [1, 2]. Further, current community environments generally contain some trivial details, such as old buildings, public facilities, street furniture, and landscapes, which are difficult to measure and integrate accurately into conventional basic design drawings, making it difficult for designers to make design judgments and decisions [3]. As a result, designers have gradually chosen to return to the design site to deeply perceive and understand the environmental details and to imagine and develop design proposals on-site [4]. Such an on-site design method originates from the \"back to the things themselves\" concept of the phenomenological movement [5], which encourages designers to immerse their proposals in community environments in order to evoke the spirit of the place [6]. However, limited by technicalities, the current on-site design of community planning mainly relies on the visual imagination of the designers [7], which is too abstract to support their intuitive design perceptions, accurate design judgments, and convenient design decisions. It therefore always leads to tedious, repetitive work [8]. In order to address the limitations relating to design intuitiveness, accuracy, and convenience, scholars have been committed to introducing the rapid development ofcomputer graphics (CG). Virtual reality (VR), a typical computer-generated imagery technology, was the earliest technology of this kind to be applied to the urban planning and design fields [9]. By assembling individual physical devices such as personal computers (PCs), head-mounted displays (HMDs), display screens, cameras, and sensors, early VR design support systems (VR-DSS), such as Geo walls, vision domes, and CAVEs, generated immersive virtual environments indoors, which allowed designers to make intuitive spatial judgments and design imaginations [10]. Meanwhile, 3D digital design objects were rendered for visualization in immersive virtual environments [11]. Improvements in computer performance provided the immersive virtual environments with more vivid details, including sound and animation [12]. The introduction of the tangible interactive interface allowed designers to interact with the virtual world in real time [13; 14]. Nevertheless, the immersive virtual environments generated by VR were detached from the physical world, rarely providing real spatial perception [15]. Additionally, creating models for immersive virtual environments costs considerable time and effort and still might not restore all the real environmental details, offering scant support for an accurate design judgment [8]. In addition, the VR-DSS is generally involved in expensive and complicated devices that are usually operated in professional scientific laboratories and not available to most designers [14; 16]. In summary, VR technology has the potential to improve on-site design intuitiveness, because it can simulate the vivid existing environments. However, the simulation of the existing environments would require a lot of effort and hardly contribute to improving design convenience. Additionally, the simulated virtual existing environments cannot support real spatial perception and thus can do nothing in terms of improving design accuracy. Subsequently, the more advanced computer-generated imagery technology, augmented reality (AR), was introduced to the urban planning and design fields into compensate for the shortcomings of VR. AR can create environments where digital information can be inserted into a predominantly real-world view [17]. With portable devices, such as smartphones and mobile tablets, AR can bring virtual design objects into real design scenes for visualization [18; 19].