W. Dierking, Quantitative roughness characterization of geological surfaces and implications for radar signature analysis, IEEE GEOSCI, 37(5), 1999, pp. 2397-2412
Citations number
54
Categorie Soggetti
Eletrical & Eletronics Engineeing
Journal title
IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
Stochastic surface models are useful for analyzing in situ roughness profil
es and synthetic aperture radar (SAR) images of geological terrain. In this
paper, two different surface models are discussed: surfaces with a station
ary random roughness (conventional model) and surfaces with a power-law rou
ghness spectrum (fractal model). In the former case, it must be considered
that for short profiles (L < 200l(0)), the measured values of rms-height s
and correlation length l may be significantly smaller than the intrinsic va
lues so and lo. In the latter case, rms-height and correlation length depen
d on the profile length L, and the surface is better characterized by slope
and offset of the roughness spectrum (which are independent of L). The sen
sitivity of the SAR signature to variations in surface roughness parameters
is evaluated by means of theoretical scattering models. For smoother geolo
gical surfaces such as most arid terrain types, single scattering is domina
nt, which means that the roughness parameters can be determined from SAR da
ta using comparatively simple algorithms. Multiple scattering processes on
rough surfaces such as a'a lava and variations of the Ideal incidence angle
due to large-scale terrain undulations make the retrieval of roughness par
ameters by means of inverse modeling much more complex. Field data of surfa
ce roughness indicate that rougher geological surfaces may be in the diffra
ctal regime at higher radar frequencies, in which the scattering characteri
stics deviate significantly from the patterns observed for stationary surfa
ces. On the basis of surface and scattering models, recently published obse
rvations of roughness data and radar signatures from volcanic, alluvial, an
d arid surfaces are examined.