Visualizing the Infrared Response of an Urban Canyon Throughout a Sunny Day

Abstract

The work presented here has consisted in placing a thermal camera in a street of the “Petit Bayonne,” one of the densest districts of French cities, in order to obtain a double sequence of photographs (shortwave) and thermographies (longwave) on a sunny day. The next step will be to repeat this sequence by numerical simulation to see how the measurements are used to calibrate the simulation and how the simulation can help to interpret the measurements.

In order to achieve by simulation a spatial resolution similar to that of the digital camera, it is necessary to use a finite element-like method. This raises specific questions concerning the scene and sky meshing, the boundary conditions (shortwave and longwave sky model), the optical and thermal properties of materials, etc.

Throughout its history, architecture has always been very sensitive to innovations in representation: central perspective, projection of shadows, axonometries, descriptive geometry, solar diagram, realistic rendering, etc. Thermography is intended to integrate this series of tools in order to support the architectural and urban projects. For this reason, it is necessary to be able to simulate these “infrared renderings.” We present here the possibilities offered by the recent advances in computing and measurement and the difficulties that remain, particularly in addressing the urban scale.