Volume modeling of soils using GRASS GIS 3D-Tools

The analysis of spatial variability of soils has been of interest to soil scientists and geographers for quite some time. Information on soil properties are usually available from a limited number of point measurements and spatial estimates are prepared in two dimensions (e.g. by interpolation or other technique). However, soil is essentially a 3D object with varying properties in all spatial dimensions. This study focuses on 3D capabilities of GRASS GIS providing new 3D tools to manipulate, analyse and model 3D landscape phenomena. For example, the multivariate interpolation method – regularized spline with tension (RST) – has a capability to interpolate and analyse geometric properties of selected soil properties in three-dimensional space. We investigate the options of modeling dynamic processes occuring in soil using simple 3D map algebra algorithms. An inherent part of scientific investigation and analysis is visualization. New GRASS visualization tools exploit 3D OpenGL graphics capabilities, coupling to external visualization software (Vis5D, Hibbard et al. 1994) allows animated views to time-dependent processes in soil volumes. An increasing number of available 3D environmental data requires a complex GIS solution for manipulation, analysis and modeling. Using G3D library with new tools for modeling and visualization, GRASS has proved that it fulfills these requirements.