The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B7. Beijing 2008
(ii) To generate relatively good DEMs from the flat
area, because the topographic features can not affect
the image.
(A) End-moraine
DEM section at the end moraine and dead-ice were
generated (Figure 9). The end-moraine is visible in each
DEMs but not for the SRTM data. Both sides of the end
moraine were depicting lacking value of HS-DEM.
From the optical image it can be seen that this area is
mostly composed by water and the water bodies were
frozen and the surface had snow. Since snow reflect the
radar weakly, the value can not be acquired.
(B) Flat area
The border between the debris area and the side-
moraine is visible in the SM-DEMs. On the contrary,
they are not distinguishable in the E1S-DEM and SRTM
DEM. It is noticed that the glacier covered with sand or
sand gravel (known as debris) is highly elevated and it
gradually decreases from the debris to the side-moraine.
On the debris area many variations of colors could be
seen (Figure 10). Apparently, such variation indicate
that these DEMs can offer detailed information.
4. CONCLUSIONS
In this study with the use of InSAR processing, we
generated DEMs by TerraSAR-X images. As a result of
comparing them with the SRTM data, it was noticed
that DEMs generated in this study can have the same
qualitative accuracy results for the qualitative
evaluation. In addition, both DEMs can show the end-
moraine and the side-moraine, which cannot be
observed by the SRTM data. Therefore, HS-DEM and
SM-DEM may be more useful than the SRTM for
monitoring purposes or for analysis of flood simulations.
Glaciers were located on the cliffs and there was a
concern that such topography might have affected the
quality of the images. However, the DEMs of almost all
areas were generated without any problem in the
present study. Only in some rare cases the mountain
ridge affected the image acquisitions. Therefore with
the data fusion of DEMs, generated in both directions
(ascending and descending), it is expected to obtain
even more accurate images.
We did not conduct quantitative evaluation which will
be conducted in the near future. Also in the current
study, occasionally, different results between HS-DEMs
and SM-DEMs were obtained. It would be interesting
and necessary as a future study to understand the causes
of such phenomena.
(Upper left:HS-DEM, Upper right: HS-CC, Middle left: SM-
DEM, middle right: SM-CC, lower left: SRTM, upper right:
ALOS/AVNIR-2)
mm— —«
1 jj&' ' «4.
v.
•t ar-v'jii
” Hi
SIHBBfflBBP? J3
■.
Figure 10. The flat area.
(Upper left:HS-DEM, Upper right: HS-CC, Middle left: SM-
DEM, middle right: SM-CC, lower left: SRTM, upper right:
ALOS/AVNIR-2)
