تحليل محيط شهري از ديدگاه كيفيت بصري (نمونه موردي: قابليت ديد در بافت قديم شهر بوشهر)

Analyzing Urban Environment Regarding Visual Quality (Case Study: Visibility in Old Fabric of Bushehr)

با توسعه جوامع، توجه طراحان به كيفيت فضاها افزايش يافته و بررسي‌هاي گسترده‌اي درباره تاثير فضا بر ادراك انسان، انجام شده است. عوامل مختلفي بر كيفيت فضاي شهري تاثير مي‌گذارند كه كيفيت بصري يكي از آنهاست. در اين راستا هدف جستجوي رابطه ميان فرم و كالبد شهر و كيفيت بصري آن است. براي تبديل كيفيت بصري به ابعاد كمي و قابل سنجش از ابزار ايزوويست در نرم‌افزار Syntax2D استفاده شده است، تحليل شبكه شهري با بررسي دو مسير با فرم متفاوت در بافت بوشهر انجام شده است. نتايج مطالعه نشان مي‌دهد مسيرهاي با فرم كالبدي متفاوت از كيفيت بصري متفاوتي برخوردارند و در طراحي‌هاي شهري توجه به ابعاد و شاخص هاي بصري به خلق محيط مطلوبتر‌ مي‌انجامد.

Visual aspect is one of those lots of aspects which influence neighborhood quality. Visibility is an important factor of environmental and urban quality. This study is concentrated to find whether the visual quality of housing and urban open space in the neighborhoods is influenced with urban form and its objective is to find the relationship between open space form of the neighborhood unique fabric, its organic pathways, a linear main access which divides this fabric to two parts and visibility. So open space visibility of neighborhood in old fabric of Bushehr and their isovist properties have been analyzed in a correlational research. The case study was a neighborhood public space in spatial configuration located in Bushehr that is surrounded by urban development and sea. Compact urban space, squares, long and narrow streets shape this fabric. One of the characteristics of this morphology is its composition as a set of rather long and narrow streets with number of squares different in shape.This study shows that isovist tool is applicable in analyzing visual quality in urban fabric. In this research two forms of urban open space has been analyzed to evaluate visibility using Syntax2D. Six isovist measures in grid and two paths have been studied that correlations between these measures have been compared with each other in two paths. Findings show that area and perimeter indices have the highest correlation. In organic path these two indices have highest value reaching Enghelab Avenue that divides this fabric in two parts and also these measures are higher in local squares than long and narrow streets. On the other hand these indices remain unchanged in linear path. Drift index that studies the longest possible line of sight raises dramatically reaching Enghelab Avenue while it almost stabilizes inside the organic path. Turning to linear path, this index is the highest at the ends and the lowest in the middle of the path. Occlusive index that is the proportion of the perimeter on the solid boundary of the environment Shows fluctuation in organic path unlike linear path. While Compactness index that shows how close the observers feels themselves to the environment shows notable variations in organic path having a steady graph in linear path. Circularity index that is the square of the perimeter to area as is influenced by details in space shows significant changes in organic path while it is nearly stabilized in linear path. It can be said as a result that urban form has relationship with its visibility; meaning that the organic path creates a variety of isovist indexes unlike linear path that divides the neighborhood fabric in two parts. Furthermore, the analysis shows that squares which are the place of social interactions are more compact than the streets of the neighborhood as they define non physical geometries and variety in the spatial experiences is achieved moving within them. Finally the study shows that the form of neighborhood open space plays an important role in its high visual quality and the quality of housing.