Stereo vision measurements of soil surfaces and their utility in testing microwave backscattering models

One of the critical constraints on examining the microwave returns from soils quantitatively is the measurement of the soil surface roughness. Unfortunately, the complexity of soil surfaces means that direct measurements are extremely time-consuming and also likely to miss possibly important structure. Thus, indirect methods of measuring soils are highly desirable. This work primarily describes the design of a stereo vision system capable of measuring soil surfaces. The stereo vision methods used in this study are first described. The measurement of a specially prepared target using the stereo vision system is then shown to display the system´s ability. The measured profile of a soil surface derived using the stereo vision apparatus is compared with that produced using a pin-board device. The resultant comparison shows that the two profiles are in good agreement when experimental constraints are taken into account. A second measurement of an area of a soil surface is then described. The resultant surface structure is then compared with measurements of the microwave backscatter derived from the ground-based synthetic aperture radar (GB-SAR) at Sheffield University. Finally, the possibilities of using this stereo vision system in conjunction with the GB-SAR apparatus for the testing of extant microwave scatter models and the development of the next generation of models is discussed