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COMPARATIVE CHARACTERISTICS OF DEM OBTAINED FROM SATELLITE
IMAGES SPOT-5 AND TK-350
Dr. V. F. Chekalin *', M. M. Fomtchenko ?'
a
1
Sovinformsputnik, 47, Leningradsky Pr., 125167 Moscow, Russia — common@sovinformsputnik.com
SESSION SS 7
KEY WORDS: Photogrammetry, DEM, Remote Sensing, SPOT-5, Stereoscopic, Imagery
ABSTRACT:
Production of various cartographic value-added products is based on use of DEM. In Russia stereo images TK-350 are used for
DEM production. The main advantage of these images is their large format (30x45 cm), practical lack of angles of tilt (x1? ), large
range of photographic width (0.1 — 3.0D) and possibility to vary the value of along track overlap from 20% to 80%. SPOT-5 images
are used for the same purpose, they are obtained immediately in digital form, their metadata are formed taking into account
information from onboard equipment. Comparing to existing analogous satellites SPOT-5 has advanced navigational equipment. For
precise determination of satellite's orbit parameters there is Doppler equipment DORIS which works over signals of Net of ground
beacons IDS. This net includes about 60 radio beacons in many countries of the world on all continents. Star sensor SS is used for
precise referencing of images. On the example of processing of SPOT-5 images in the frame of international experiment HRS-SAP
(area 7, Iran) and TK-350 images using the same geo-data there is performed a comparison of produced DEMs in accuracy
characteristics and economical parameters.
1. SOURCE DATA
On 29.07.2003 SOVINFORMSPUTNIK received the source
data on CD-ROM for production of DEM over Rasht area of
test site 7 Iran from CNES list presented in Denver in
November 2002. The received materials include the following
data:
CD-ROM with digital images of SPOT-5 stereopair in TIF
format; metadata files for them in XSL format; fragments of
test DEM and 28 maps in DGN format for Microstation 95
software package. Geodetic coordinates of DEM are given in
zone 39 of UTM projection on WGS-84 ellipsoid, height datum
Bandar Abbas. Date of survey 13.07.2002.
Corner Coordinates of Images (WGS-84):
Left Image Coordinates (pxl
]B-37 37.32^N.L —49" 12*4a8" E 1 ]
28-3737 177 N L=-50 31542" E 12000 1
3B=36"50"59"N L=50/21?31"E 12000 12000
4.B=37°06:20N L=49 0309" E 1 12000
Right Image Coordinates (pxL
hLB-37538'18$"N L 49 12*25"E 1 |
2B=37"22'16"N L=350°31’ 09" EF 12000 1
3B=36"50"45"N L=50°20" 57" E 12000 12000
4.B-— 37. 06:43" N- L5 49 02* 45" E ] 12000
Orientation Angles:
Orientation angle: L 13°.640525 R14°.424381
Incidence angle: L 23°.012006 R 22°.466202
2. QUALITY ASSESSMENT OF SOURCE MATERIALS
The analysis of the received SPOT-5 stereo images showed that
they are rotated 90° clockwise. The dynamic range of image
optical densities 1s very narrow — about 50 grayscale levels
(Figure 1) thus forcing to use the procedure of maximal
possible histogram stretch in ERDAS IMAGINE before
processing.
ld Histogram for imagery.t - inl xj
Bin Function : ; Direct
histogram
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Figure 1.1. Histogram of the source SPOT-5 stereopair over
Rasht, Iran (left image)
