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imoto and M.
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International
30M.
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Friplet Image
International
ROM.
ASSESSMENT OF GEOMETRIC ACCURACY OF VHR SATELLITE IMAGES
W. Wolniewicz
Institute of Photogrammetry and Cartography, Faculty of Geodesy and Cartography,
Warsaw University of Technology, Pl. Politechniki 1, Warsaw, Poland, 00-661
w.wolniewicz@gik.pw.edu.pl
Commision I, WG 1/2
KEY WORDS: Remote Sensing, Photogrammetry, High resolution, IKONOS, QuickBird, Geometry, Orthorectification
ABSTRACT:
VHR images of earths’ surface are more frequently used and taken advantage of in substitution to aerial photographs. Geometric
dependences of creation orthophoto based on aerial photos are known and distinguished from images of VHR. Results of work led
are presented in this article within the confines of an investigative project under the Committee of Scientific Research of Poland
concerning the geometric mechanism of VHR images and corrections. Two test fields have been made up for this project (city,
country and mountain terrain). For those test fields, images from IKONOS, QuickBird were ordered. In the conducted research the
angle of the axes was take into consideration: 0 ? — 15 ? In each test field area, after the identification of control points on the VHR
images, about 30 — 90 GCP have been measured with GPS in accuracy of 10 cm. For image geometric corrections in this project
two types of available DTM models in Poland have been applied with varying accuracy. Geometric correction have been realized
with the aid of generally available software as PCI Geomatica 9 with taking into consideration RPC method and camera ( rigorous)
model. Throughout the work investigated, in each of the individual scenes of VHR various distribution and number of GCP was util-
ized for the process of orthorectification. Accuracy of orthorectification process received in result of led work, for VHR images at
different configuration of geometry and methodology. Detailed results of experiments allow determining the optimal foundation for
different methods of geometric corrections from IKONOS, QuickBird images and establishing effective process of dependence and
defining geometric accuracy for different applications.
1. INTRODUCTION
In recent years we can observe rapidly increasing interest in the
practical application of very high-resolution satellite imaging.
The reasons are: from one side a need for satellite information
about the surface of the earth to be applied in many different
fields, and from the other side a need to achieve digital tech-
nologies optional to traditional photogrammetrical solutions
(aerial photographs).
Poland is particularly interested in taking advantage of satellite
imaging type VHR. This interest results mainly from an urgent
need to cover the area of the country with such products as or-
thophotomaps, DEM or topographic database, in order to reach
the same level of coverage as the countries of Western Europe.
Therefore it is natural to see in VHR imaging a source of data
quickly reaching this level of coverage. The project for creation
of an orthophotomap of IKONOS images for an area of 50.000
sq kilometers, for the needs of LPIS (The Land Parcel Identifi-
cation System programme was initiated in 1995 as an alphanu-
meric identification system for all agricultural parcels in EU)
is the practical manifestation of such interest in VHR imaging.
Also the Regional Operations Center (ROC) is situated in Po-
land. We are also considering the option of using QuickBird
images.
In order to verify practical applications of such imaging,
research was conducted, which comprised generating satellite
orthophotomaps achieved with a use of many different
techniques in various circumstances for the same land areas,
obtained from the most commonly used VHR systems, i.e.
IKONOS-2 and QuickBird-2.
The goal of this research was to compare procedures and
technologies for producing orthophotomaps based upon the
high-resolution satellite images for the selected testing area,
which is the area of Warsaw, flat area, as well as Nowy Targ,
an area of large de-leveling, foot-hills area. In the framework of
investigations were provided accuracy evaluations of the
achieved satellite orthophotomaps in different variants of
geometrical correction. In this paper is presents detailed
assessment of the planimetric accuracy of the panchromatic
orthophoto from VHR images.
2. EXPERIMENT
The scenes achieved by the systems IKONOS and QuickBird
for different time slots and angle deflections were used for the
survey. For flat area (Warsaw) the deflection from axis in
relation to nadir point are 5 degrees for QuickBird
(DigitalGlobe provided a test image acquired over Warsaw,
Poland) and 6.5 degrees for IKONOS. At the same time for
mountain areas (Nowy Targ) they are respectively 9.5 degrees
for QuickBird and 12 degrees for IKONOS (INTA SPACTURK
provided a test image acquired over Nowy Targ, Poland).
Precise characteristics of the imaging used have been presented
in table no. 2.
In order to realize the process of ortho-adjustment, we
presumed a photogrammetry matrix with the use of a GPS
system. For determining coordinates of these points a
TRIMBLE 4700 satellite dual-frequency receiver with Micro-
centere antenna was used. The survey was done with a use of
