Section: New Results

Outdoor InfraRed Thermography

Vision enhancement through Infrared imaging for transport infrastructures

Participant : Jean Dumoulin.

Fog conditions are the cause of severe car accidents in European western countries because of the poor induced visibility. Its occurrence and intensity are still very difficult to forecast for weather services. Furthermore, visibility determination relies on expensive instruments and does not ease their dissemination. Lately, it has been demonstrated the benefit of infrared cameras to detect and to identify objects in fog while visibility is too low for eye detection. Over the past years, such cameras have become more cost effective. A research program between IFSTTAR and Cerema studied the possibility to retrieve visibility distance in a fog tunnel during its natural dissipation. The purpose of this work is to retrieve atmospheric visibility with a technique based on the combined use of infrared thermography, Principal Components Analysis (PCA) and Partial Least-Square (PLS) regression applied to infrared images.[44] and [17]

Outdoor thermal monitoring of large scale structures by infrared thermography

Participants : Jean Dumoulin, Antoine Crinière.

With the constant increase of the road traffic coupled with the ageing of transport infrastructure, studying and developing robust system which allows to monitor and assess those structures is of growing interest. Among the techniques used [1], thermal monitoring with infrared thermography appears to be a good compromise between a non-intrusive method and possible added value after post-processing of acquired data. Through the past decade studies have shown the ability to monitor concrete and asphalt structure by active IR thermography. On site measurement using passive thermography have also been studied, by applying qualitative methods and quantitative one. These methods have been used to perform punctual control of various duration (few hours to few days). However, infrared thermography, when it is used in a quantitative mode (not in laboratory conditions) and not in a qualitative mode (vision applied to survey), needs to process thermal radiative corrections on the raw data acquired in real time, to take into account the influences of the natural environment’s evolution with time. The ICT system called “IrLaW” is based on a multi sensing approach. It connects and synchronizes information acquired by a weather station, a GPS and an infrared camera. To fulfill ICT objectives (OGCcompliant), a specific hardware architecture was also designed and studied to allow the whole system integration in a TCP/IP network. [29]