3-5-1
Airborne Mapping System with
GPS-supported Aerotriangulation
Deren Li Xiuxiao Yuan
Wuhan Technical University of Surveying and Mapping
129 Luoyu Road, Wuhan, 430079, P R. CHINA
KEY WORDS: GPS, Kinematic GPS Positioning, GPS-supported Aerotriangulation, Combined Bundle Adjustment,
Accuracy, Reliability
ABSTRACT
In conventional aerial photogrammetry, high precision photogrammetric point determination is always carried out by
aerotriangulation using a great deal of ground control points around the perimeter and in the center of a block area
because the exterior orientation parameters of aerial photographs are unknown. A technological revolution in
photogrammetry has taken place since Navstar Global Positioning System (GPS) was applied to determine the 3D
coordinates of exposure station positions during the photo flight missions. GPS-supported aerotriangulation is conducted
by a combined bundle adjustment with GPS navigation data, which replaces the essential ground control points with
GPS-determined camera positions. The simulation experiments of GPS-supported aerotriangulation can date back at
least to 1986. Recent investigations show this method is now practical. We have been engaged in theoretical studies,
software development, and related to experiments and production on the field since 1990. So far, most-abundant research
achievements are obtained in terms of the theory and application. In this paper, we first derive the mathematical model of
combined bundle adjustment with GPS navigation data from the geometry between camera and airborne GPS antenna,
and then describes briefly a software package WuCAPS Gra (Wuhan Combined Adjustment Program System for GPS
Navigation Data and Photogrammetric Observations) developed by the authors, which serves the purpose of combined
bundle adjustment for photogrammetric and non-photogrammetric observations. At the end of the present work, a set of
actual aerial photographs, at the image scale of 1:5,000-1:37,000, with airborne GPS data taken from five sites in China
were processed by our WuCAPS G />s. The empirical results have verified that the accuracy of the combined bundle
adjustment with 4 XYZ ground control points around the comers of block area is very closed to that of the conventional
bundle adjustment with 3 additional parameters, which leads to an 88% reduction in field survey and 75% saving in
production cost, and can meet the specification of topographic mapping at small or medium scale by GPS-supported
aerotriangulation without ground control. This shows the ample applicability and the economic benefit of kinematic GPS
relative positioning in high accurate photogrammetric point determination.
1. INTRODUCTION
As is now well known, high precision point determination
with airborne remote sensing data has always been one of
the most fundamental problems in aerial photogrammetry.
According to the principle of the geometry reversal in
photogrammetry, the interior and exterior orientation
elements of aerial photographs must first be known in
order to reconstruct the measuring stereo geometric
models. In the past 60 years, however, the interior
orientation parameters of camera were mainly determined
by means of laboratory methods, while the exterior
orientation parameters of aerial photographs were based
solely on indirect determination by aerotriangulation
using ground control points. Despite many attempts to
determine the exterior orientation elements or individual
parameters of exterior orientation during the photo flight
missions, none of these efforts was able to achieve a
practical breakthrough.
With the development of man-made satellite technology,
microelectronics and computer science, the USA
Department of Defense (DoD) began to develop
NAVSTAR GPS (Navigation System with Timing and
Ranging Global Positioning System) in early 1970’s. The
system is intended to provide positioning practically
anywhere on the Earth and at any time. Designed
originally for navigation purposes in the American
military, it has been extended to extremely precise
positioning of airborne cameras and sensors. Some
experiments showed that the accuracy of positioning by
differential GPS carrier phase observations to aerial
photogrammetry is in the order of a few centimeters
(refer to WGS84 coordinate system), which make it
attraction also for photogrammetric purposes, and GPS
offers in the future new possibilities to determine the
orientation parameters during the photo flights. Therefore,
the principle and methods of employing these additional
data in an aerotriangulation adjustment are studied. The
combined adjustment for photogrammetric observations
and GPS-determined data of the camera positions is
