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- 1. Photorealistic 3D Simulation Just pretty gimmicks with limited value? Ho Lok Man (10613082d)LSGI4321 – Geo-information for Urban and Regional Studies11/5/2011
- 2. Table of Content Tableof Content ........................................................................................................................................... 0 Table of Figures ............................................................................................................................................. 1 Topic 3 ........................................................................................................................................................... 2 Abstract ......................................................................................................................................................... 2 Background ................................................................................................................................................... 2 Usage of photorealistic 3D simulation .......................................................................................................... 5 Disadvantages of 3D simulation.................................................................................................................... 5 Examples: Using 3D simulation for analysis.................................................................................................. 6 1. Urban Planning and Transportation System Planning and Management ................................... 6 2. Disaster Prevention and Rescue Simulation ................................................................................ 8 Conclusion ..................................................................................................................................................... 9 References .................................................................................................................................................. 10 Table of Figures FIGURE 1 - A 2D URBAN PLAN. SOURCE: (DESIGN + DEVELOPMENT MANAGEMENT CONSULTING SERVICES , 2011) ........................2 FIGURE 2 - A 3D URBAN PLAN. SOURCE: (HALLYUWORLD PROJECTS , 2009)...............................................................................3 FIGURE 3 - 2D (UPPER LEFT), 3D (UPPER RIGHT), AND 2.5D (BOTTOM) SIMULATION. SOURCE: (PENNINGA , 2008) ............................3 FIGURE 4 - WORLD TRADE CENTER TRANSPORTATION HUB. SOURCE: (SILVERSTEIN PROPERTIES , INC, 2011) ..................................4 FIGURE 5 – 2D GRID-BASED WITH 3D VECTOR MODEL. SOURCE: (E VANS, 2009) ..........................................................................7 FIGURE 6 - 3D SIMULATION OF BEHAVIORS OF PEDESTRIAN MOVEMENTS. SOURCE: (CROOKS, HUDSON-S MITH, & PATEL, 2010) ........7 FIGURE 7 - FINDING SHORTEST PATH BETWEEN THE FIRE STATION AND THE DISASTER SITE. SOURCE: (KWAN & LEE , 2005) ...................8 FIGURE 8 - 3D DUST AND UNKNOWN GAS SIMULATION. SOURCE: (VROEIJENSTIJN & HENDERSON, 2011) .......................................9
- 3. Topic 3 It hasbeen argued that photorealistic 3D simulation is just pretty gimmicks with limited value. Critically review the validity of this statement. Abstract Nowadays, photorealistic 3D simulation had been argued that it is just pretty gimmicks with limited value. The validity of this statement will be reviewed critically in this paper. This paper could discuss the topic by several sections: background of photorealistic 3D simulation, usage of photorealistic 3D simulation,the disadvantagesof photorealistic 3D simulation, and followed by some photorealistic 3D simulation examples. Background Since many years ago, urban planners use some urban simulation for understanding the cities better. We usually heard of 2D simulation and 3D simulation. Basically, 2D simulation takes place in two- dimensional space, usually drawn with line and a flat background.For 3D simulation, it takes place in three-dimensional space with objects able to move on three axes. When comparing with 2D simulation and 3D simulation, 2D simulation is simply a plane with some lines and polygons (Figure 1 - a 2D urban plan). However, only professions can understand the meaning of the lines and polygons: maybe some of them are roads, some are building blocks, or some may rivers, with some agriculture land. Public may not have enough knowledge to understand the maps. Figure 1 - a 2D urban plan. Source:(Design + Development Management Consulting Services, 2011)
- 4. For the 3Dsimulation, it is a more fancy and eye-catching simulation. It contains blocks, tubes, sphere etc.;users (both the urban planners and the public) can identify them by the visualized effect. Users can even rotate it with 180o degrees, or even 360 odegrees, to know more about the plan and the region. By 3D simulation, a complex building can be shown in 3D easily instead of just a few lines and polygons. A 3D simulation can show more details, as in Figure 2 - a 3D urban plan. Source: (HallyuWorld Projects, 2009). Figure 2 - a 3D urban plan. Source: (HallyuWorld Projects, 2009) For additional information, actually, there are numerous types of simulation. Apart from 2D simulation and 3D simulation, there is one called “2.5D simulation”. 2.5D simulation uses two-dimensional methods to “create an illusion of 3D graphic”, and it also called as “pseudo-3D rendering”(Sanders, 2011). That means, 2.5D simulation is similar to 3D simulation, but no rotation can be done for the model.The illustration of differences between 2D, 2.5D and 3D are as follows (Figure 3 - 2D (upper left), 3D (upper right), and 2.5D (bottom) simulation. Source: (Penninga, 2008):
- 5. Figure 3 -2D (upper left), 3D (upper right), and 2.5D (bottom) simulation. Source: (Penninga, 2008) Also, there is one called “photorealistic 3D simulation”. It is a kind of 3D simulation that aims to make the model as real as the reality(Boddy-Evans, 2011), by using shading, texturing, and lighting.By texturing with photos, the photorealistic 3D simulation will become more realistic than a normal 3D model. Apart from that, a photorealistic 3D simulation can simulate the effects of light source, shadows, winds, motivation of trees, sea shore, dust in the road, fires etc. Thus in the ideal case, if taking screen captures from a photorealistic 3D model, that screen capture would be looks like a photo taken from a scene, or even having more details than a normal photo. The following figure is an example of a screen capture photorealistic 3D model (Figure 4 - World Trade Center Transportation Hub. Source: (Silverstein Properties, Inc, 2011)). As we can see, this model involves details of the main buildings. This screen capture is looks like a photo, but it actually still in construction in New York until the quarter of 2014. Also, as we can see, by the usage of shadows, light sources, the 3D models become more realistic.
- 6. Figure 4 -World Trade Center Transportation Hub. Source: (Silverstein Properties, Inc, 2011)
- 7. Usage of photorealistic3D simulation Photorealistic 3D simulation is mainly used for simulating a 3D digital city. It has good potential applications, from simply displaying data or 3D maps, to huge, complex integrated applications, such as virtual city tour, urban planning, transportation system planning and management, disaster prevention and rescue simulation, environment and landscape simulation, project planning and evaluation, Location-Based Services (LBS), 3D navigation, digital archives, building and reconstruction of ruins or specific scenarios, military and national security, entertainment and game industry etc.(Choi & Chan, 2010, p. 26). By photorealistic 3D simulation, apart from the building blocks, trees or roads can be simulate, the sound, wind and dust, rainfall and water, fire and smoke, light and shadow, sun and moon, or even the traffic flow can be simulated like the real world. These characteristics of 3D simulation enhance the visual effect, and shorten the analysis speed for decision makers, as they can directly seeing the 3D models and visualized results. For the later sections, the usage of photorealistic 3D simulation in urban planning, transportation system planning and management, and the disaster prevention and rescue simulation will be discussed with examples. Disadvantages of 3D simulation Some criticizers may criticize that, 2D may enough for decision making, as decision makers may only be the professionals. Public may not need to know the details of the planning projects, or other information of the land. So, they may ask: do details really a matter? Photorealistic 3D simulation involves huge amount of data, and the time cost of rendering is very high. By adding light source and shadows, a large amount of complex computation will be involved. It increases the time used in rendering 3D models. In general, the market price for a high definition (HD) 3D rendering will cost between US$1000 and US$2000 for one single still image (Jironomo Visualization, 2010). The cost of generating a 3D animation would be even much higher. This high price is due to long time rendering and many experts involved in the 3D rendering. Thus, when comparing to 2D simulation, the cost of 3D simulation would be much higher.Also, as 3D simulation involved a large amount of data, the cost of maintaining would be relatively higher than maintaining a 2D simulation database. Due to these reasons, some may criticize that 3D simulation is not worthy and with limited value. However, by the following section, the examples will be verifying this statement.
- 8. Examples: Using 3Dsimulation for analysis Apart from visualization, 3D simulation is always beneficial for analyzing.When doing the urban planning, transportation system planning and management, and the disaster prevention jobs, the benefits of using 3D simulation were maximized. In this section, two parts would be discussed: 1. photorealistic 3D simulation in urban planning and transportation system planning; 2. Disaster prevention and rescue by photorealistic 3D simulation. 1. Urban Planning and Transportation System Planning and Management Photorealistic 3D simulation is very useful for urban planning. Apart from visualizing the details parts of the cities, or the building blocks, the 3D models can even simulate the wind direction andlight source for enhancing the analysis process. For wind direction simulation, it is very important for urban planning. It is because the urban climate is mainly determined by the limitation of air exchange (Barlag & Kuttler, 1990/1991). In day time, the hottest part of a city would be the building tops. If these heatsadding with the heat emitted by the pollutants cannot be dispersed appropriately, it will raise the environmental impact on the residential population. Thus, air paths are essential for a well-planned and well-balanced city. This is the case in Hong Kong too. According to the urban design guidelines released from the Planning Department in Hong Kong (2006), Hong Kong “needs more winds for thermal relief and comfort in the built environment”. It is because Hong Kong has the subtropical climate with a very hot and humid summer, air paths are becoming more important than in other countries. To ensure the new city plan introduces enough wind to the urban areas, a wind direction simulationis very useful. Mathematically, the climate and meteorological models are usually in grid-based. However, the city models are vector based (Evans, 2009), and a vector based analyze would be resulting a more accurate results (Figure 5– 2D grid-based with 3D vector model. Source: (Evans, 2009)).Thus, using 3D models in vector format to simulate the wind direction is much better when comparing to use the 2D simulation. It is because the 2D simulation is normally using the grid based system to carry out the wind direction analyzed. Also, for the light source simulation, it is important for urban planning too. In European cooperation project, there is one project called “POLIS”. It aims to utilize the solar energy European cities by implementing strategic town planning and local policy measurements (ISPOL, 2011). Solar energy is highly depends on the brightness of the sun light. Apart from that, the orientation and availability of the area would also affect the reception of the passive solar energy. Through 3D simulation, the
- 9. light source ofthe study area could soon be identified, and the amount of light that can receive from the area could then be calculated easily. The 3D simulation eases the site selection of solar energy. Figure 5– 2D grid-based with 3D vector model. Source: (Evans, 2009) For the transportation system planning and management, photorealistic 3D simulation can simulates the traffic flow to enhance the analysis process. As thinking of the mass transit railway system is shut down for one week without any pre-notice, the transport system in Hong Kong will results? As an expert in the transportation system planning and monitoring, he must monitor the movements and keep the traffic flows moving under these circumstances(WINSLOW , 2005). A 3D simulation simulating the traffic flow, or the behaviors of pedestrian movements (Figure 6 - 3D simulation of behaviors of pedestrian movements. Source: (CROOKS, HUDSON-SMITH , & PATEL, 2010)) could be very useful for the administrator make decisions when using a complete visualization in real time. Figure 6 - 3D simulation of behaviors of pedestrian movements. Source: (CROOKS, HUDSON-SMITH , & PATEL, 2010)
- 10. 2. Disaster Preventionand Rescue Simulation Photorealistic 3D simulation is very useful for disaster prevention and rescue simulation too. It is because by using 3D models, the situations of having fires, smokes, flooding, or dust can be simulated. For an example, by using 3D simulation, if there is a site having fire, the 3D model can immediately generate the shortest path between the entrance of the site and the disaster site. In 3D simulation, the shortest path uses a modified Dijkstra’s algorithm that can operates on the 3D network. According to Kwan and Lee (2005), using this integrated 3D network saves more than 1/3 of the travel time, for reaching the disaster site. If shorten the rescuing time, more life in the disaster site can be saved. Figure 7 - Finding shortest path between the fire station and the disaster site. Source: (Kwan & Lee, 2005) Apart from enhancing the quality of real time decision, photorealistic 3D simulation can also be a training tool. The 3D models can have a space-time prediction and shows the potential affected area(ZHENG& YANG, 2011). Also, the 3D models can simulate fake situation, which can help training the decision makers. Unlike the real world, life would not be lost if any wrong decision made. Users can customized the 3D model, by simulating different kinds of disasters, to train the ability of the users’ emergency decision making. The training may speed up the decision making time when the real disaster comes to the real world. The following figureillustrates an emergency case that the road is full of dust and unknown gas (Figure 8 - 3D dust and unknown gas simulation. Source: (VROEIJENSTIJN& HENDERSON, 2011)).
- 11. Figure 8 -3D dust and unknown gas simulation. Source: (VROEIJENSTIJN & HENDERSON, 2011) Conclusion In conclusion, photorealistic 3D simulation is not only a gimmick. 3D simulation is more realistic than 2D simulation, which helps for analysis by visualization. 3D simulation is always being customized, and fit the users’ needs. As the simulation is dynamic, users can “walk” or “fly” through the study area, and let them understand the area better. 3D simulation is most useful in the urban planning, transportation system planning, disaster prevention and the rescue simulation. It is because 3D simulation can simulates the wind direction, light sources, traffic flow, fire, smokes, flooding, dust, or other natural environment. These characteristic enhances the reality of the 3D models. Also, because of the complexity of the real world, this kind of visualization speeds up the time of decision making. Planners and decision makers can easily make decisions or plans by simply seeing the effect of the model. Apart from the town planners and the decision makers, the public can involve into the town planning process, as users could find easier to understand when using 3D simulation.
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