Author/Editor		Brzoska, Jean-Bruno; Flin, Frederic; Lesaffre, Bernard; Coleou, Cecile; Lamboley, Pascal; Delesse, Jean-Francois; Le Saeec, Bertrand; Vignoles, Gerard
Title		Computation of the surface area of natural snow 3D images from X-ray tomography: two approaches
Type		članek
Source		Image Anal Stereol
Vol. and No.		Letnik 20, št. Suppl 1
Publication year		2001
Volume		str. 306-12
Language		eng
Abstract		Once fallen on the ground, snow undergoes a structure metamorphism governed by local temperature and humidity fields. Local 3D curvature is a governing parameter of metamorphism, whereas surface area, directly related to surface energy, can provide a valuable bridge between 3D fine-scale and 1 D field-scale snow cover models. X-ray tomography was applied to natural snow at ESRF in order to parameterise the fine-seale behaviour of snow in avalanche risk prediction models. Starting from raw data consisting of a B/W 3D data file, two main approaches are considered. The former uses a triangulation procedure derived from the "marching cube" algorithm. Before triangulation, the B/W data are converted into grey levels and preprocessed in order to smooth the final mesh. The other uses a distance map of the object, from which the field of nonnal vectors is computed. Assuming the tangent plane approximation, the effective projected area of cach surface voxel is derived from simple geometric laws. A cross-validation of both methods is provided on a natural snow image.
Descriptors		TOMOGRAPHY, X-RAY COMPUTED SNOW IMAGE PROCESSING, COMPUTER-ASSISTED