A Comparative Analysis of Sanandaj Urban Area Examples, using Isovist and Visibility Graph Analysis

Isovist and Visibility Graph analysis tools are used to quantify and measure the quality of space, and despite their lack of maturity and evolution, they are considered to be the future of space analysis tools by researchers. This study was undertaken with the purpose of introducing the aforementioned tools for analyzing Sanandaj’s urban areas. In this study, four different urban areas in Sanandaj were selected and after the software was prepared, the areas were analyzed by Isovist and Visibility Graph analysis. Then, the charts and data obtained from these regions were compared. The interpretation of the findings of the Isovist and Visibility Graph analysis reveal that in the old region builders used a sort of inherent and collective standard for measurements despite building without modern urban development maps. Amongst all the four urban areas of Sanandaj, this region has the greatest visual richness and diversity; in addition, the special analysis of neighborhood size indicates harmony and balance in this region. Moreover, the results illustrate that the nearest wall and special neighborhood size indices have the highest correlation, followed by jaggedness which has the highest correlation with revelation. However, openness factor and the nearest wall have the lowest correlation. The openness factor indicates the degree observers feel themselves in the space and also present their visual dominance over the space. In this factor, the standard deviation values of the new and the middle areas are low which indicates that the openness coefficient is the same in all areas and the individual experiences monotony and boredom. The feeling of being in space and attention to the environment in these regions (especially in new areas) is significantly reduced. In addition, in this index the high standard deviation for informal settlement areas is merely due to the diversity of the streets and sidewalks, but in the old area, the high standard deviation is due to the combination of sidewalks with squares and various open spaces spread in the region. Thus, the only area with visual richness and diversity is the old area. The nearest wall index signifies the domination of the wall in the informal settlement area over the spaces. In the middle area, the surrounding long streets and linear views along with visual opening and open spaces with lower degree of circumscription appear. According to this index, the old area has the lowest standard deviation which indicates visual space sequence and the feeling of the existence of a united identity in the area by the observer. Since the revelation index indicates the rate of change in the field of view during movement, the highest value of kurtosis and drift in the revelation index of the old area indicates that this area has the most variations and changes in vision for the moving observer and meets the quality of mystery in vision and visual richness. Finally, the results concerning the four types of regions in Sanandaj indicate that the Isovist and Visibility Graph analysis factors reveal the similarities and differences between these regions in terms of space properties and visual quality. Therefore, using these tools in decision-making related to urban design can significantly contribute to the promotion of the visual quality of the urban fabric.