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Description Test Area
I II III IV V
Sensor & Instrument SPOT3 SPOT3 SPOT3 SPOT3 SPOT3
HRV2 HRV2 HRV2 HRV2 HRV2
Date of Acqusition 04/95 04/95 04/95 04/95 04/95
Viewing Angles R8.7 R8.6 R8.6 R8.6 R8.6
Film/Digital Imagery 1AP/1A 1AP/1A 1AP/1A 1AP/1A 1AP/1A
Table 1. Characteristics of SPOT test data
The photo scale was approximately 1:300,000 in SPOT level 1AP film products.
3.2 Ground Control Point and Check Points
: To aid identification of ground control points, series of 1:50,000 plots of the scenes were produced. These were initially
georeferenced using the satellite positional data that came from SPOT header file. The operator can identify good points
by their location and improve their visibility. The GCPs were selected among the 1st, 2nd, 3rd, and 4th geodetic control
point, which maintained by the NGI(National Geography Institute) in Korea.
The NGI maintains all national control points in order to provide reliable and accurate references for the horizontal and
vertical positions necessary for all the projects related to land such as mapping, cadastral surveys, and various public
development projects. The national control points are divided into two categories, primary and secondary. The number
of the former are about 1,300 existing 1st- and 2nd- order horizontal control points, and the latter are approximately
15,000 3rd- and 4th- order control points. Survey records and final data of control points, including horizontal control
points, vertical control points (Bench Marks) and traverse points, are filed in books available for public use.
To verify the modeling accuracy, we used 89 check points covering the same test area. The check points came from
1:5,000 digital map, which produced by NGI's digital map database. The database is composed 10 layers: road, railway,
river, building | & II, vegetation, facility, topography, administrative or regional boundary, and anotation. Most of the
check points were acquired at road layer and all the points were verified the readability in SPOT stereo viewing .
3.3 Hardware and Software
The SPOT stereoscopic modeling was performed on the P2 analytical plotter and the LH Systems digital
photogrammetric workstation DPW770. For the analytical plotter the software released BINGO-SPOT 3.0 was used,
that can be used in triangulation with SPOT stereomodels in the PHOCUS environment. In DPW770, we used the
software released SOCET 4.2.0
3.4 Triangulation
3.4.1 Analytical Plotter: Level 1AP images were are stretched in the line direction to compensate for scale differences
in the x and y directions in oblique viewed photography. This stretching must be eliminated during the measurement of
the image coordinates. To perform the interior orientation, the fiducials have been measured by the means of the manual
method. Affine transformations were used , and the resulting standard deviation(o ) were less than 2 /m for the entire
test data.
For the exterior orientation, we measured the image coordinates of the control point with P2 analytical plotter. After
that, we collected the orbit parameters for all images and entered the control point coordinates in a file. The adjustment
of the SPOT data was performed with the BINGO program. The orientation parameters have been computed by athe
bundle adjustment including manual measurement of 89 check points.
3.4.2 Digital Photogrammetric Workstation: All of the digital measurement was performed with the SOCET SET
software. The SPOT math model in SOCET SET is a push-broom sensor model that uses the header data supplied with
the SPOT 1A or 1B scenes. SOCET SET uses up to 13 parameters to adjust the SPOT sensor model. SOCET SET uses
a classic, fully weighted, least squares bundle adjustment to solve for these parameters. The adjustment of the SPOT
imagery was performed scene by scenes. Ground control and tie points between scenes were independently observed
over the test area.
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000. 531
