## 1 Introduction  
In recent years, more and more historical buildings and cultural heritage sites have been preserved using 3D modeling techniques for digital modeling for a variety of applications by general users or research groups, including tour guides, disaster prevention, urban planning, restoration, and reuse, and the scope of applications is constantly expanding [1]. There are also more and more studies on the establishment of 3D virtual city models that take real-world data into consideration for planning [2]. The 3D urban visualization and analysis platform is conducive to the direct browsing of social institutions and citizens, as well as the analysis of urban big data, and can be further expanded [3], thus, 3D visualization of the building information model has become key to communication [4]. The link between 3D visualization and information can allow users to better understand the project [5], and 3D information modeling technology plays a very important role. The application of 3D digital tools and the information modeling system in the conservation of historical buildings and cultural heritage sites can accurately record and present the actual sites, and thus, expand the user's ability to explore and interact with the historical district environment. BIM and 3D-GIS are currently mostly defined as 3D design tools with the ability to generate 3D visual models of cultural heritage. In visualization, commercial software packages can be used to prerender and generate photo-like lighting and surface material rendering [6]; for example, Autodesk 3 dsMAX, Autodesk Maya, Artlantis, and Lumion can also be combined with related integrated commercial software packages in the field of animation simulation, such as Navisworks, Infrawworks, CityEngine, Lumion, or cloud platforms (BIMserver), to provide users with the possibility of a real-time tour of historic blocks and experience the actual historic buildings. Besides, data modeling and data visualization are integral parts of planning a smart city, and planning professionals currently seek new methods for real-time simulations [7]. At present, most research on 3D modeling technology or virtual platforms focus on model visualization, prerendering graphics, dynamic simulation, and virtual tours of the scene. While 3D rendering and virtual technology have been used for a long time, and is still an effective way to provide users with sufficient detail about urban blocks and buildings, it lacks the environment to allow users to interact with their surroundings in real time. The impact analysis of \"what-if scenarios\" frequently takes a significant amount of time and resources, and virtual reality (VR) is a potential tool for addressing these challenges. VR is a computer technology that replicates an environment, whether real or imagined, and simulates the physical presence and environment of a user to allow for user interaction. VR technology research can assist urban planners, stakeholders, and communities to further understand the roles of planning policies in creating a smart city, particularly in the early design stages. The significant roles of technologies, such as VR, in targeting real-time simulations and visualization requirements for smart cities are emphasized [7]. Furthermore, game environments provide a highly interactive experience, and allow users to interact with various objects, such as cities or buildings [8; 9]. The game engine can provide realistic rendering technology, a physics engine, animation effects, API support, etc., which can assist planners to simulate the construction situation, experience the actual scene, increase the authenticity and interactivity, and provide the ability of tool development. Modern game engines like Unity allow users to create realistic 3D environments containing terrains as well as natural and artificial objects easily and swiftly. In addition, recent advances of game engine capabilities enable effortless implementation of virtual VR compatibility [10].