INTERSECTION AND COMBINATION OF DIGITAL ELEVATION MODELS - METHODS AND APPLICATIONS
Manfred Sigle, Olaf Hellwich, Andre Köstli
INPHO GmbH
Smaragdweg 1
7000 Stuttgart 1, Germany
Commission IV
ABSTRACT:
Three-dimensional surface descriptions, which exist in the form of digital elevation models, are well suited - by using any
mathematical function - for a combination of different types of surface data (DEM, digital slope model, digital soil value model,
etc.), as well as for the intersection of these digital surface models with polygon areas. Corresponding methods were realized in the
DEM program system SCOP.
Typical application examples are the derivation of height difference models from two DEMs, a subsequent volume computation, the
determination of slope statistics from a digital slope model, or the production of soil loss prediction maps by combining the
influence factors for soil erosion.
KEY WORDS: DEM, volume computation, soil loss prediction, polygon overlays
INTRODUCTION SCOP has been used world-wide by numerous organizations
for all types of DEM projects, from large-scale engineering
In addition to the conventional DEM applications (isolines, projects up to the generation of national DEMs. SCOP is a
profiles, perspective views) arithmetic operations on the DEM joint development by INPHO GmbH (Prof. Ackermann) and
data like the DEM intersection and the functional combination by the Photogrammetric Institute of the Technical University
of DEM data represent a new challenge for DEM systems. Vienna (Prof. Kraus). The structure of SCOP is shown in
fig. 1.
DEM intersection and combination methods are already used
for volume computation. In addition, they open many new
fields of application to a DEM system.
DTM generation DTM applications Output
terrain data
SCOP.DMS
data management
Up to now surface data describing the terrain (e.g. elevation,
slope) have usually been intersected with polygon areas by
polygon overlays. In a first step the surface data had to be
classified and described by polygon areas with constant class
values (e.g. slope class areas derived from a digital slope |
model). This classification includes a considerable loss of SCOP.SLOPE faster
information which leads to erroneous results, especially in wes
Y SCUP.PERSPECT
cases where the polygon data are used for a functional
SCUP.ISULINES vector
graphics
SCOP.PROFILE
combination with other terrain data (e.g. for soil loss | SCUD DTM — Gis-
prediction). DM inter pala ton SCOP.INTERSECT Mterfaces
Therefore methods had to be developed for intersection and SCOP.PIXEL
combination which made full use of the three-dimensional numerical
1 1 B output
surface information of a DEM. SCOP.PLOT
Together with the necessity of having a SCOP module for focal — 1. ——— —
volume computation, the above considerations were the reason other
for the development of the program SCOP.INTERSECT. systens
2. THE DEM PROGRAM SYSTEM SCOP Fig.1: SCOP modules
SCOP is a multi-purpose program system for the generation
and application of digital elevation models (Kraus et al. 1982, 3. DATA STRUCTURE OF THE SCOP DEM
Ackermann 1991). Its flexible high-quality interpolation
methods produce DEMs of cartographic quality. SCOP The heart of a DEM system is the digital elevation model
includes all common DEM application modules which derive which is characterized by the quality of its interpolation
follow-up products like single heights, isolines, profiles, methods and by the efficiency of its data structure.
volumes, perspective views, digital slope models and raster
graphics DEM representations.
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