Capturing Chromatic Effects in Urban Environment

To consider the multiple colour variations under the light, climate and movement, we propose the notion of sensory chromatic effect. Between pure colour analysis and broader visualscape approaches, the chromatic effect is a tool to handle the ordinary perception of coloured architecture in everyday situation. It is analogous to the notion of sonic effect defined by Augoyard et al. [2]. In order to detect such chromatic effects, a survey was conducted in the city of Nantes (France) using experiential walks. It involved 12 people during 2 days with bright sky. Each participant was granted with a camera worn around the neck with video mode ON. While walking, the camera recorded the position, the views and the sounds. The instruction given to participants was: “When you walk, pay attention to the colours that surround you. When it’s interesting, take a picture and explain the situation orally.” The methodology inspired by commented walks [14] requires (1) the full transcription of each participant’s words; (2) establishing the links between words and pictures taken by participants; (3) identifying the chromatic effects perceived by participants from words and pictures; (4) making a fusion of all individual discourses into a single one; (5) building a synthesis of shared chromatic effects along the route. By this way, a repertoire of about twenty chromatic effects has been defined in several categories. Some major detected effects are for instance visual appeal effect, pushing colours effect, flicker effect, black hole effect, etc. Based on these results, two kinds of graphical representations have been proposed to handle the chromatic effects in the context of an urban or architectural project: expressive photomontages, based on the pictures taken by participants, that exaggerate the effect in order to make it intelligible; analytic cartographies that illustrate the spectrum of chromatic effects along the route.