Ahmed Mansouri

Measuring Streetscape Complexity Based on the Statistics of Local Contrast and Spatial Frequency

Streetscapes are basic urban elements which play a major role in the livability of a city. The visual complexity of streetscapes is known to influence how people behave in such built spaces. However, how and which characteristics of a visual scene influence our perception of complexity have yet to be fully understood. This study proposes a method to evaluate the complexity perceived in streetscapes based on the statistics of local contrast and spatial frequency. Here, 74 streetscape images from four cities, including daytime and nighttime scenes, were ranked for complexity by 40 participants. Image processing was then used to locally segment contrast and spatial frequency in the streetscapes. The statistics of these characteristics were extracted and later combined to form a single objective measure. The direct use of statistics revealed structural or morphological patterns in streetscapes related to the perception of complexity. Furthermore, in comparison to conventional measures of visual complexity, the proposed objective measure exhibits a higher correlation with the opinion of the participants. Also, the performance of this method is more robust regarding different time scenarios.

Electrophysiological Evaluation of Perceived Complexity in Streetscapes

Abstrct This study represents an experimental research based on the electrophysiological evaluation of perceived complexity in streetscapes. Two physical measurements of perceived complexity, based on RMS contrast statistics and fractal information, were compared to human judgmental responses issued from brainwaves using Epoc Emotiv neuroheadset. The results indicated that frequency bands showed significant results in alpha and beta power bands in occipital and frontal electrodes, respectively. The higher the degree of familiarity with the streetscape image, the higher the degree of relaxation reflected by the increase of alpha power. Alpha power increased in dark streetscape images. RMS contrast statistics as well as fractal dimension values showed a positive correlation with beta band power associated with arousal and attention.