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As a part of the Swedish mine detection project MOMS, an initial field trial was conducted at the Swedish EOD and Demining Centre (SWEDEC). The purpose was to collect data on surface-laid mines, UXO, submunitions, IED's, and background with a variety of optical sensors, for further use in the project. Three terrain types were covered: forest, gravel road, and an area which had recovered after total removal of all vegetation some years before. The sensors used in the field trial included UV, VIS, and NIR sensors as well as thermal, multi-spectral, and hyper-spectral sensors, 3-D laser radar and polarization sensors. Some of the sensors were mounted on an aerial work platform, while others were placed on tripods on the ground. This paper describes the field trial and the presents some initial results obtained from the subsequent analysis.

The thermal signatures of surface and buried land mines vary widely with time of day, weather, soil type, soil moisture content, and mine burial depth. There have been recent advances in modeling these effects, but until these models are fully developed and validated we will continue to rely on measured data. This paper witll present signatures in the medium-and long-wavelength infrared (MWIR and LWIR) spectral bands for surface and buried M19, M15 and VS1.6 anti-tank mines at two locations, a temperate site and an arid site. We will show that the apparent contrast of these landmines is substantial throughout the diurnal cycle except during thermal crossover periods after sunrise and sunset. Our results show that the mine signatures are well above sensor noise and that further improvements in sensitivity or resolution are not required. The paper will also present LWIR images of landmines buried in dirt and gravel road environments taken on a cold winter day and discuss the intriguing and unexpected differences observed between the images of landmines buried in dirt and gravel.

This paper presents the work on the detection of land mines using IR-images. Experiments have been performed where outdoor time series of IR contrast have been measured for wax filled antitank mines in sand and for real mines in a gravel road. For antitank mines in the sand box the contrast dependence of time lap between burial and measurement has been analyzed for a period of four months. The diurnal contrast variation of an anti tank mine buried for two and a half year in a gravel road has been calculated. Statistical correlation between apparent temperatures and weather parameters for different cases have been calculated. The purpose is to understand the origin of the contrast and to be able to predict the contrast at different times and under different conditions.

During summer 1998 a series of tests were conducted in Finland in order to find out how Ground Penetrating Radar (GPR) technology can be utilized at both the project and network level, when surveying the wearing course thickness of gravel roads. The second objective was to investigate the possibilities of applying dielectricity information obtained using the GPR surface reflection method when determining the quality of the gravel road wearing course. In this study GPR was tested at the project level on highway 9241 Simo in Northern Finland, where the information provided by the GPR and laboratory research was used in designing and proportioning a new wearing course. In the network level studies, performed in the maintenance areas of Kemi and Karstula in Northern and Central Finland the goal for using GPR was to inspect the condition and thickness of the wearing course and evaluate the need for additional wearing course material. The total length of the roads under survey was approximately 200 km and both a 1.5 GHz ground-coupled antenna and a 1.0 GHz horn antenna were tested in this study. The research results show that GPR can be used to measure the thickness of the wearing course, the average measuring error against reference drilling measurements being 25 mm, which is considerably larger than the error of radar measurements in paved roads. To a great extent this is due to the fact that the thickness of the wearing course varies greatly even in the road's cross-section and thus a single reference thickness does not represent the actual thickness of the area measured with the GPR. The wearing course can often get mixed up with lower layers, which makes it difficult to determine the exact layer interfaces. For this reason reference information must always be used along with the GPR measurement results. Of the two GPR antennae tested, the horn antenna proved to be the more effective in measurements. The dielectric value of the wearing course, measured using the horn antenna surface reflection method, represents well the suction properties of the wearing course. High dielectric values reflect the water sensitive and frost susceptible wearing course materials where as low values reveal the lack of binder. A quality rating of the wearing course by its dielectrics and layer thickness is also suggested. In the measuring results analysis and presentations, GIS-maps proved to be invaluable.© (2000) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.