Finding True Position of Buildings in Orthophotos
W. Wolniewicz PhD, P. Jaszczak *
Institute of Photogrammetry and Cartography, Faculty of Geodesy and Cartography,
Warsaw University of Technology, Pl. Politechniki 1, Warsaw, Poland, 00-661
href="mailto:w.wolniewicz@gik.pw.edu.pl">w.wolniewicz@gik.pw.edu.pl,
p.jaszczak@interia.pl
* Student of Faculty of Geodesy and Cartography, specialty Photogrammetry
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 (flat – city, foothills terrain). For those test fields, images from
IKONOS, QuickBird were ordered. For image geometric corrections in this project four types of
available DTM models in Poland with various accuracy have been applied. In each test field area,
after the identification of control points on the VHR images, about 30 – 100 GCPs have been
measured with GPS in planimetric accuracy of 10 cm. 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 numbers of GCPs was utilized for the process of
orthorectification. Accuracy of orthorectification process was received in result of led work for
VHR images with influence of different type DEM used. 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 technologies 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
orthophotomaps, DEM or topographic database, in order to reach the same level of spatial digital
data 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 Identification System program was initiated in 1995 as an alphanumeric
identification system for all agricultural parcels in EU) is the practical manifestation of such
interest in VHR imaging.
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 how influence
different DEM for producing orthophotomaps based upon the high-resolution satellite images for
the selected testing area. There were two test fields: Warsaw as flat area, and Nowy Targ as
foothills area of de-leveling up to 500 meters.. In the framework of investigations were providing
accuracy evaluations of the achieved satellite orthophotomaps in different variants of geometrical
correction. In this paper is presented detailed assessment of the planimetric accuracy of the
panchromatic VHR images.
