The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part Bl. Beijing 2008
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Figure 11. Representation of the channel with the grid-base
DEM and the corrected DEM
Figure 13. Representation of the terraces with the grid-base
DEM and the corrected DEM
Figure 12. Representation of the cliff and pond with the grid-
base DEM and the corrected DEM
all the programs are running on the Windows XP platform,
based on Visual C++ 2005 and OpenGL 2.0.
The above pictures (from Figure 11 to Figure 14) show the
results of the experiment.
The above 3 couples of pictures give an obvious contrast of the
existing grid-based DEM (top) and the corrected DEM (bottom).
As mentioned above that grid-based DEM cannot handle abrupt
changes in elevation, each left picture of the three figures shows
a relative smooth terrain surface. Many terrain morphology
features, such as shoulder lines, ridges, valleys, cliffs, etc.,
cannot be accurately or clearly described. Due to the inherent
structure of grid DEM, when there are abrupt changes or terrain
features inside the grid mesh, the peak will be clipped, the
channel will be filled and the cliff will be smoothed, etc. (left
picture of each figure). Then terrain representation distortion
occurs. This can lead to incorrect result of hydrological
modeling, geomorphology application, ecology application and
other digital terrain analysis.
When the terrain feature information is integrated to the grid,
the terrain representation has taken great changes (right picture
of each figure). In figure 11, the channel is obvious and its
bottom and edges are described by feature lines. And similarly,
in figure 12, there is a cliff and a pond, using a feature line, the
cliff can be easily handled and a feature polygon represents the
pond. At last, in figure 13, there are many terraces in this area,
which are not obvious in the left picture, when the feature lines
are embedded, the terraces can be seen clearly, which is
