CUHK electronic theses & dissertations collection

In this thesis, the author has explored the feasibility of 3D visibility analysis for visual quality assessment via the aid of modelling tools, virtual geographic environment (VGE) and WebGIS, which may be beneficial to build a measurable evaluating standard of visual environment in urban open spaces, and referential to create an atmosphere with improved visual comfort in guiding planning or design processing. Considered as long-term significance, 3D visibility analysis for visual quality assessment is potential in enabling the quantitative analysis between urban open spaces and visual perception of human, providing appropriate standard for evaluation of visual environment, and bringing the future urban planning and design fields into rational and reasonable.Due to the development of 3D modelling software and VGE, their applications have been attempted in 3D visibility analysis by a few previous scholars, exploring the possibility of representation for urban environment in 3D and the feasibility of spatial relationship analysis with visual factors. Lots of progress has been made with the participation of the modelling software such as AutoCAD and 3Ds Max, or analytical platforms such as ArcGIS and VGE. As the extension of preceding study, the author is going to discuss improvements and innovations of some tools applied in visibility analysis and visual quality computation, such as Open Simulator as a VGE Platform. Moreover, due to the easy access for entry-level programmer and the public, Google SketchUp (a type of modelling software) and WebGIS have also been tested whether suitable for the analysis handling, considerably decreasing the programming development difficulty. Both SketchUp and WebGIS are thought to be well accepted by thepublic, as SketchUp has been popularised in 3D modelling and WebGIS has been familiar as the form of websites for a long period, which may enable the dissemination of visibility analysis to the public.From a pilot study of progresses based on the researches of past scholars, the author developed an improved method for 3D visibility analysis, by mathematically deriving the visual factors from the spatial relationship analysis of buildings, terrain and other geographical features. A few quantitative factors as the distance, solid angle and visual field (a distribution of occupied solid angle in all directions) valued in spherical coordinate system were adopted as the basic units for visibility levels. Starting from the space prototype, the research has also focused on several aspects possibly associated to the visual effects in open spaces, including the openness, enclosure and ground coverage for edge, the distribution and dispersion for skyline, and the visibility of individual building for landmark. For further comparison, the variances of those figures were also noticed during space scales changing for the prototype, in order to find possible connection or changing trend before and after. Moreover, experiments of 3D visibility analysis have been designed and put into practice for real scenes to discover the similarities or differences among prototypical spaces and reality, and Piazza del Campo (Siena, Italy), Piazza San Marco (Venice, Italy) and Olomouc centre area (Olomouc, Czech) have been selected as the first group of candidates. As a complementary study, the central campus area of the Chinese University of Hong Kong (CUHK) were also taken into consideration as an experimental site, for comparison of disparities with those classical scenes. Those would be possible references for conclusion of similarity or discrepancy among various spaces, in order to find out spatial general pattern, or reveal the actual affections of visual factor values in the reality.在本論文中，作者基於建模工具、虛擬地理環境和网络地理信息系統（WebGIS），對三維可視性分析和視覺評估的可行性進行了探討。概括而言，這項探討將有助於在城市開放空間可評估測量屬性的輔助下實施城市規劃和設計，以期打造具有更佳視覺舒適性的城市環境。而從長遠意義上考量，三維可視性分析和視覺評估亦是實現城市開放空間和視覺感知之間聯繫的定量分析前提，並為城市環境評價提供適當標準，使今後的規劃和設計更趨理性。由於三維建模軟件和虛擬地理環境的發展，部分學者已在三維可視性分析中進行些許嘗試，試圖了解在城市環境中的三維空間關係與視覺因素進行相關分析的可行性。且在此研究之前，部分實驗已於個別建模軟件如AutoCAD和3ds Max、或分析平台如ArcGIS和虛擬地理環境中取得可觀進展。基於以上前人的成就，筆者一方面期望在分析工具上進行適度革新，另一方面追尋可視性分析和視覺評估算法上改進的可能，從而在本文中做出個人領域上的創新。在此之中，考慮到入門難易程度和公眾接納程度，筆者採納了若干開發難度較低的工具相互搭配，如谷歌草图大师（Google SketchUp，一種輕量級建模軟件）、Open Simulator（虛擬地擬環境平台）和网络地理信息系統，來輔助進行城市開放空間的可視性分析。谷歌草图大师常被用作於平民化的三維建模，Open Simulator可提供形象化的現實模擬和交互環境，而WebGIS以眾人熟知的網站形式進行交互操作，這些工具在大眾中擁有較高的普及程度和較低的接納門檻，同時亦為可視性分析在大眾中普及提供了一定的可能。而從三維可視性分析的方法改進上，筆者基於先前學者的部分試點研究，在數學推導上對地形、建築物等地理特徵產生空間關係的計算方法提供合理改進。基於球坐標系，作者用距離、球面度和視角分佈（各方向上視角的分佈）等量化數值為城市開放空間進行基本可視單元的度量；亦從空間原型出發，研究集中討論了若干視覺效果，如開放度、圍合度和地面覆蓋度，天際線的分佈和離散程度，個別建築物的可視性分佈等，在城市開放空間可視效果度量上的作用。此外，通過進一步比較各空間之間可視數值上的差異，量化地去理解空間的視覺效果差異，並可依照參數變化的對比尋找可能存在的變化趨勢和相關性，對空間的可視性有更深的理解。在本論文的實驗中，作者亦採用了部分真實場景進行三維可視性和視覺評估的分析，以期發現與原型空間相似性或差異性。坎波廣場（意大利錫耶納）、聖馬可廣場（意大利威尼斯）和奧洛穆茨中心區域（捷克奧洛穆茨）作為城市經典空間作為第一批實驗場景，而後續的香港中文大學中央校園作為普通場景的對比亦被納入實驗場景之中，以便進行相似性和差異性的探討。採用真實場景的實驗有助於更好地將現實中城市開放空間的視覺特性與演算結果進行結合，揭示各可視數值的實際表現意義，並在空間原型的相似性上進行合理探討。Lin, Tianpeng.Thesis Ph.D. Chinese University of Hong Kong 2016.Includes bibliographical references (leaves 110-116).Abstracts also in Chinese.Title from PDF title page (viewed on 05, October, 2016).Detailed summary in vernacular field only.Detailed summary in vernacular field only.Detailed summary in vernacular field only.Detailed summary in vernacular field only