International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part Bl. Istanbul 2004
Module PHOTOMOD StereoDraw performs production and
editing of vector layers in stereomode. A significant set of
export/import vector formats is supported. Module
PHOTOMOD StereoVectOr is used for display and editing of a
map being updated in legend signs. The module has convenient
two-monitor mode of work. Module PHOTOMOD Mosaic is
used for production of fragments of orthoimages from satellite
and aerial images and their mosaic. The functions of brightness
adjustment provide seamless orthomosaic. It is possible to
export it directly to MapInfo and ArcInfo cut into sheets or
trapeziums of required size. The module PHOTOMOD
ScanCorrect allows to use inexpensive polygraphic scanners
after their accurate calibration.
4. ORIENTATION OF IMAGES IN GEODETIC SPACE
In order to construct geometric terrain model there were
performed the required technological processes: interior
orientation — to set parameters of connection of pixel coordinate
system of digital images with commonly used photogrammetric
image coordinate system and account of distortion of imaging
system; relative orientation — for further production of free
stereo model; exterior orientation — for production of geometric
terrain model in geodetic space; production of epipolar images
— for the process of automatic stereo matching of corresponding
points on stereopair images. Production of terrain model in
geodetic space using photogrammetric system PHOTOMOD
from SPOT-5 images was done using RPC polynomials which
are equations of connection between photogrammetric
coordinates X,Y,Z and geodetic X,Y,Z.
As a result the following accuracy of construction of terrain
model in geodetic space was achieved:
For SPOT-5 images
RMSy , = +/- 12.82 m in plane;
RMSy = +/- 7.0 — 15.3 m in height
For TK-350 images
RMSy y = H- 14.94 m in plane;
RMS} = +/- 8.58 m in height
5. PRODUCTION OF DEM FOR THE TEST AREA
According to the plan of experiment production of DEM was
done 15.32 km x 15.32 km in size with 40m spacing within the
test area TS7 (Rasht, Iran) with the corner coordinates:
49°52°15.796” — 50°02°43.250” E
37°04°16.4437 -37°12°27.853” N
The analysis of computer variant of DEM obtained using “Z-
Space” system showed that in the flat part of test area there are
a lot of relief “outbreaks” up to 40-50m in height. The
mountainous part of DEM does not have such errors of
determination of heights of terrain points. Due to this reason
postprocessing of DEM included mainly the procedures of
automatic smoothing of DEM using Grimson method within flat
areas. The outlook of DEM corrected in such a way is shown on
Figure 6.
Figure 6. Outlook of DEM produced by “Z-Space” system
from TK-350 images
The comparison of DEM produced from satellite TK-350
images with the test one showed the following accuracy
characteristics:
RMSy; = +/- 14.1 m An = 0.1m
The histogram of differences of their heights is shown below in
Table 1.
Table !
No. Differences, m Number of differences %
1 0-5 51 810 36
D 5.1-10 38 029 28
3 10.1-15 25 647 18
4 15.1-20 15 613 9
5 20.1-25 8 128 5
6 25.1-30 4 697 2
7 30.1-35 2167 |
8 35.1-40 566 0
9 40.1-45 237 0
10 45.1-50 13 0
11 50.1-55 7 0
The similar analysis of computer variant of DEM obtained
using PHOTOMOD system showed absence of significant
“outbreaks” (see Figure 7). This resulted in the histogram of
differences of its heights with the heights of test DEM (Table
2).
Table 2
No. Differences, m Number of differences %
1 0-5 53 264 37
2 5.1-10 38 142
3 10.1-15 23 370
4 15.1-20 15 526 aH
5 20.1-25 9 539
6 25.1-30 5017
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