| Popis: |
This paper addresses the feasibility and operational application of different infrared (IR) imaging systems in road traffic to improve security of individual motor vehicles at conditions of low visibility, especially in fog. Extensive field measurements were carried out at different weather conditions, mainly fog and haze, utilizing three IR imaging sensors in different spectral bands in the near and thermal infrared. Additionally, a CCD camera in the visible band was used for comparison purposes. Measurements were performed on public roads and a test road which was equipped with heated and unheated radiation reference sources and thermal beacons. Furthermore, the atmospheric spectral transmission and relevant meteorological and aerosol parameters were measured. A mathematical model, SIMIS (simulation model for IR scenes), was developed and applied to generate and analyze thermal images of the test road. The spectral dependencies and radiation properties of fog and haze were modelled with LOWTRAN 7. Apparent radiances, temperatures, and contrasts of the references sources were simulated as a function of distance. The contrast transmission and effective IR visibility was derived and compared to the measured IR-imaging sensor data. From the analysis an assessment of the performance of IR-imaging sensors at fog conditions has been deduced. |
