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