Acquisition method of high accuracy ground control points for high - resolution satellite imagery
Takeshi MIYATA and Masataka TAKAGI
Kochi University of Technology
Tosayamada-cho, Kochi, 782-8502, Japan
Email: 085517e@gs.kochi-tech.ac.jp
ABSTRACT
Currently, high-resolution satellite imageries as less than 1m resolutions are used in many
fields. For example, land use mapping, urban planning, disaster monitoring, and so on. They
are expected to be overlaid with other GIS data and updating existing maps. Therefore, high
accurate geometric correction is necessary to analyze high-resolution data. However, it is
difficult to acquire highly accurate ground control points (GCP) and the corresponded image
control points (ICP). Because, acquisition of the high accuracy ICP by using visual
interpretation is very difficult. In this study, acquisition method of high accuracy GCP and the
corresponded ICP was discussed.
Field surveying by kinematic using GPS was used for generating polygon data for GCP.
And center of gravity of the polygon was used as GCP. Error of coordinates in GCP dataset
by field surveying can be decrease by calculating center of gravity of the polygon. Calculation
results showed less than 0.1 m error. It was enough accuracy as GCP.
An efficiency of center of gravity calculation for high accurate ICP were evaluated by
generating simulation images from GCP polygons. The simulations were carried out under
some conditions as follows ;
Shape of GCP polygon. – Elevation difference in GCP Polygon.
Off-nadir angle of satellite image. – Error in classification.
The simulated images were generated from GCP polygons by transformation using
collinearity equation. Center of gravity as ICP were also calculated the simulated polygon
image. The results showed shape of polygon and off-nadir angle influence to accuracy of ICP.
Required accuracy were satisfied under the condition that “off-nadir angle” ranges from 0°to
10°and “flat area”.
1. INTRODUCTION
High-resolution satellite image are expected to be overlaid with other GIS data and updating
existing map. Therefore, highly accurate geometric correction is necessary to rectify
high-resolution data. In photogrammetry, many metric targets were used for geometric
correction. However, the targets are so small that it is not taken in high-resolution satellite
image. Therefore, acquiring high accuracy GCP and the corresponded ICP is difficult.
Especially, acquisition of the high accuracy ICP by using visual interpretation is very difficult.
