Topic1 09624775d

09624775D CHIN SZE WING / LSGI 4321 Individual Paper / Submitted on 15-Oct-2011

LSGI 4321 Geo-information for Urban and Regional Studies


Discuss how 3D GIS can facilitate decision making for urban and regional planningAbstractNowadays town planners have to deal with urban planning tasks including assessing visual impact, analyzing glare, etc. As the popularity of 3D GIS, they are recommended to apply it to carry out decision making related to regional planning.IntroductionIn this essay in what ways 3D GIS can help planners to make decision regarding town planning. To begin with, the definitions of 3D GIS and town planning are introduced. Secondly, the details like natures, functions, development, strength, limitations, applications and software of 3D GIS are discussed. Thirdly, some of the tasks of 3D GIS related to planning are demonstrated, including some background information, effectiveness, limitation and possible improvement. Lastly, the concluding remarks about the discussion of the 3D GIS and the comments of those tasks are expressed.Definitions3D GIS is defined by Leung (2010) as an information system which can represent the real world entities through visualization, analysis, management and share geographic data in three-dimensional. It is also a seamless transitions among the street, local and global data. Moreover, it allows us to analyze and edit with 3D data in order to make a reliable decision for any organizations and fields.Whereas town planning (or urban and regional planning) is, according to Lewis Keeble (1969), the art and science of ordering the use of land and locating of buildings and communication routes for the sake of securing the practicable degree of economy, convenience and beauty as much as possible. To be precise, planning is an art that uses scientific tools. GIS is a scientific tool using statistics and demographics, and the equations that we use to forecast citizen needs. 3D GIS can acts as a tool whilst town planning is the aim. In order to maximize the extent of economy, convenience and beauty of a city or a regional, 3D GIS can be used to help making planning decision by visualizing, analyzing, managing the sharing the 3D data from a small area to a globe. ComponentsRegarding the nature, the components of 3D GIS include elevation, imagery, sub-surface, models and multi-patches, topographic and other features like street furniture, buildings, landmarks, trees, roads, etc (Leung, 2010).Functions3D GIS can serve many purposes about spatial and aspatial entities, which is similar to its 2D counterpart. The main functions are as follows (Leung , 2010):Visualize: to visualize raster and vector data to give you 3D feature, terrain, subsurface and volumetric views. For example, 3D visualization of buildings, etc



Manage: to create and maintain 3D data, all within a 3D context. For instance, 3D GIS database management, etcAnalyze: to perform complex surface, volumetric, and visibility analyses that can include time or temporal elements. For instance, visual impact analysis, etcShare: Help decision makers and influencers better understand your work by sharing it in a realistic 3D perspective. For example, export video animations, etc.DevelopmentGIS developers have make efforts for years in order to create and improve 3D GIS for the betterment of planners, some of them are summarized below.1980’s: Much work had been done on 3D data modeling using the concept of simplicial complex (Carlson 1987), voxel data structures (Jones, 1989), etc. 1990’s: Academic studies in Fritsch and Schmidt (1995), Kraus (1995) and Pilouk (1996) were presented the use of TIN data structure to demonstrate 3D terrain.2000’s: A web-based 3D GIS for visualizing geospatial data has been widely used. For example, VRML, GeoVRML, X3D, etc (W3C, 2011).2010’s: Cloud computing technologies greets as it can do massively distributed and parallel processing (Park, 2010) (Sivan Design, 2011) (DropBox, 2010).Strength and Limitations3D GIS allow understanding from many different viewpoints by an adequate cover of the aspects of reality. However, higher costs have to be spent on labor and hassles. Also, it complicates data management and user interfaces.ApplicationSome of the application areas include:Urban planning (for example, shadow analysis, city planning & visibility analysis)Civil engineering (for instance, viewshed analysis & elevation analysis)Facilities management (for example, interior transportation networks)Defense / public safety (for instance, emergency 3D routing)SoftwareThere are many 3D GIS software available in the GIS market which allows users to visualize, mange, analyze and share 3D GIS data.ArcView 3D Analyst from ESRI: It is an ArcGIS for Desktop extension that enables effective data modeling, surface analysis and data visualization (ESRI, 2011).Imagine VirtualGIS from ERDAS: It is a powerful yet easy-to-use visual analysis tool that offers GIS functions and capabilities in a 3D environment (ERDAS, 2011).GeoMedia Terrain from INTERGRAPH: It is a package for basic elevation processing, terrain analysis, feature generation and 3D visualization (INTERGRAPH, 2011).GIS Topographer from PAMAP: PAMAP GIS is a vector and raster data system for handling 3D data in order to perform similar 3D GIS tasks (PCI Geomatics, 2011)



3D GIS for Urban PlanningThe planning authorities has challenges of the imbalance or ineffectiveness of urban planning. To remedy the situation, 3D GIS should be used to help planners for making some reliable planning decision. Some of them are illustrated as below:1. A Change of Building Form: a 3D visualization to facilitate art aspect of planningBackground3D building data can be acquired using a variety of terrestrial and non terrestrial techniques, including aerial photogrammetry, aerial laser scanning, terrestrial measurement, close range photogrammetry, terrestrial laser scanning and official cadastral information have been widely applied. Different combinations of building forms and façades for the proposed urban development are then illustrated in Fig.1, which are easy to conceive and understand.

Fig.1: Comparison of 4 different building forms using GeoGlobe (Wu et al, 2010)EffectivenessEffective displays of 3D objects depend on processing power and memory capacity of graphics card in computer.LimitationThe existing approaches, even in combination, are too time intensive and expensive for 3D data acquisition and updating (Brenner et al., 2003).ImprovementAggregation (merge) and typification (reduce number) can be used to generalize 3D city models and to create models in different LODs automatically (Mao, 2010).



2. Shadow Analysis: a 3D analysis to facilitate the science aspect of planningBackgroundA shadow analysis gives an accurate representation of the shadows that will be cast by a proposed development or building on its surrounding environment at any given time as illustrated in Fig.2. It allows local planners to make informed decisions on planning applications by identifying the impact that a proposed development will have on its surrounding environment in terms of overcastting shadows (ESRI, 2011).

Fig.2: Shadow analysis template in ArcGIS 10 (ESRI, 2011) (a) First sun points are created using the Create Sun Skymap script tool. (b) A fan of volumetric shadows is calculated. (c) The colored points represent window locations, which windows will receive sun (yellow), which windows will receive shadows from existing structures (blue) and which windows will receive shadows from the new proposed structure (red) are shown. (d) The area affected by shadow of existing buildings, shadow of the proposed building or no shadow effect at all can also be calculated.EffectivenessIt depends on the quality of data (i.e. building shape, terrain, etc) (ESRI, 2011).LimitationOccasional differences exist between computed shadow volumes and observed ones.ImprovementIt is better to increase the resolution of terrain data when comparing shadows. Also output Sun distance should be increased to reduce impact of improper datum transformation on the shadow (ESRI, 2011).



3. Noise Simulation: a 3D visualization to facilitate the science aspect of planningBackgroundTo facilitate road traffic noise problem, the noise effects generated by the proposed development can be predicted using 3D GIS and noise modeling, which is aimed to quantify and identify the noise problems and evaluate the possibility of migrating road traffic noise around the subject site (Fig.3). Firstly, with 3D city models, customized LIMA (2003) packages can be used to solve equations for noise models.. Next, 3D digital terrain model would is carefully designed with the help of 3D GIS. Then, photorealistic 3D noise model is generated in VRML format and 3D immersive visualization system is used to create a virtual reality environment (Law et al, 2011)

Fig.3: Photorealistic 3D noise model of Tai Po Road in Shatin (Law et al, 2011).(a) Current situation. (b) Predicted noise levels of unmitigated scenario. (c) Proposed cantilever barrier scenario. (d) Predicted noise levels with cantilever barriers.EffectivenessFor the measure noise level, 90% confidence interval falls within the range of ±3 dB(A) (Law et al, 2011).LimitationUncertainties like data input for noise calculation and data source of city model exist.ImprovementFurther studies should be carried out to solve those uncertainties.



4. Glare Analysis: a 3D analysis to facilitate the science aspect of planningBackgroundGlare is the reflected light from the glass or mirror of the façade commercial building. Glare analysis is useful for planners to estimate effect of glare created from the proposed commercial building to the surrounding. It leverages much of the same techniques as the shadow analysis i.e. to create a virtual point position for the sun, and projects that location (with parallel rays) through the face or façade that you want to analyze, to generate a multi-patch volume. The thing that is different is that the virtual sun position is rotated around the façade’s 3D plane so the volume created is the reflected sun in Fig.4 (otherwise known as glare) (ESRI, 2011).

Fig.4: Example glare result (against the orange façade) (ESRI, 2011)EffectivenessThe process of creating potential glare volumes can be generated effectively using the new Skyline Tools available in ArcGIS10 as shown in Fig.5.

Fig.5: A model with glare volumes can be created Using ArcGIS 10LimitationSometimes the glare volumes have an offset from the buildings.ImprovementYou can adjust the location of where the glare volume begins and ends by changing the minimum and maximum radius.



5. Visual Impact Analysis: 3D visualization to facilitate the art aspect of planningBackgroundView-shed analysis is used to analyze the visual impact after development. View-shed is the locations visible from one or more specified points or lines. View-shed maps are useful for finding well-exposed places for communication towers are demonstrated in Fig.6.

Fig.6: Examples of 3D view-shed analysis (Spatial Imaging, 2001)(a) An application for telecom tower siting and military reconnaissance (b) What you can see and what can see you can be determined (c) A strategic approach for a target of interest can also be determined (d) A range and field of view and multiple locations and any desired height can be set using 3D view-shed analysisEffectivenessIt is difficult to evaluate the visual impact which is art aspect of planning.LimitationSubjectivity, vagueness of language and magnitude of impacts exist.ImprovementQuantify Viewshed, which see if the target is visible for each pixel (Danese, 2011).

where I=Identifying viewshed, V=viewshed maps, n=number of maps



ConclusionOne of the main tasks for urban planners is urban design, with a view to visualizing the potential effects of urban development. Besides the traditional planning process, a modern planning practice exists. However, most of these approaches use 2D data, only a few utilize 3D data. Due to the availability of 3D-data, authorities and planners should take advantage of 3D GIS in facilitating decision making in town planning.In this paper we reported some applications of 3D GIS in helping decision making of urban and regional planning, namely – a change of building forms and facades, shadow analysis, noise simulation, glare analysis and visual impact assessment. It is convinced that 3D GIS is now becoming an integration of strong database management and powerful analysis and visualization environments.3D GIS have been developed for decades. GIS professionals have strived for years to develop some applications in facilitating urban and regional planning. Most of them are reliable but some limitations (e.g. time, money and complication) make town planners being reluctant to use the new technology. To remedial the problems, as a GIS professional, we should keep finding new methods to improve the limitation.References- Brenner, C., Dold, C., Jülge, K., (2003) Fusion, Interpretation and Combination of

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