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DEM Creation
Surface interpolation
INTERCON
interpolates a raster Digital Elevation Model
(DEM) from a set of digitized contours. It uses linear
interpolation between contours to produce a faceted model that
may be subsequently filtered to produce a smooth model.
INTERPOL interpolates a full surface from point data. The
interpolation procedure can be either a distance-weighted
average or a potential model.
TREND calculates linear, quadratic and cubic trend surface
polynomial equations for spatial data sets, and interpolates
surfaces based on those equations.
Context Operations on DEM's
SURFACE calculates slope, aspect and shaded relief images from
a digital elevation model, and can create shaded relief images from
slope and aspect images.
VIEWSHED determines all cells visible from one or more
viewpoint cells situated on a surface. Output is a new image in which
cells in view are assigned a value 1, viewpoint cells are assigned a
value 2, and cells not in view are coded as zeros.
WATRSHED determines the watershed of one or more target
cells situated on a surface. It examines the aspect image of the surface,
created with the SURFACE module. To determine if a cell belongs to
the watershed, the direction of flow is evaluated from the aspect
image to determine whether it flows into a known watershed cell.
Through multiple sweeps down and up the image, the watershed is
"built" until no further growth is possible. Flat areas are assumed to be
capable of flow in all directions.