Simplified determination of optical surface properties for IR signature modelling


  • Nils Karlsson
  • Jan Fagerström
  • Tomas Hallberg
  • Roland Lindell

Publish date: 2014-04-07

Report number: FOI-R--3770--SE

Pages: 23

Written in: Swedish


  • BRDF
  • DHR
  • Sandford- Robertson
  • infrared signature modeling


The purpose of the work described in this report is to examine whether it is possible to use data from handheld reflectometers to obtain values for the parameters in a BRDF model that can be used for calculation of IR-signatures. This would mean simplified measurement procedures. The measurements can be made in field environment. It would avoid the risk of discrepancies between the samples used in the laboratory and the real surface of for example vehicles that are to be modeled. Measurements were performed with commercially available reflectometers and laboratory equipment such as BRDF and DHR spectrometers. Data that directly can be used to determine the parameter that describes the specular lobe width in the BRDF model from the handheld equipment is missing. It turns out that there is a correlation between the proportion of diffuse reflectance and specular lobe width. In the case when it is possible to determine the proportion of diffuse reflectivity with handheld devices also the lobe width parameter may be determined. Parameter values that are based on handheld measurements and laboratory measurements are calculated and compared. Examples of images that are rendered with the respective different parameter values are displayed and compared in the report. The work shows such compliance that data from the handheld equipment is useful for signature calculations with BRDF models. However, one should recall that this is a limited study, and that the hand-held equipment's spectral resolution is limited to six wavelength bands between 0.9 to 12 ?m