Andreas Eckardt 
  
PERFORMANCE OF THE IMAGING SYSTEM IN THE LH SYSTEMS ADS40 
AIRBORNE DIGITAL SENSOR 
Andreas ECKARDT', Bernhard BRAUNECKER?, Rainer SANDAU® 
Deutsches Zentrum für Luft- und Raumfahrt (DLR), Germany 
Institute of Space Sensor Technology and Planetary Exploration 
andreas.eckardt QG dlr.de 
"Leica Geosystems AG, Switzerland 
bernhard.braunecker Q leica-geosystems.com 
"LH Systems GmbH, Switzerland 
sandau Q [h-systems.com 
Working Group I/3 
KEY WORDS: Camera, CCD, Sensors, Image Registration, Radiometric Qualities, Photogrammetry, Remote Sensing 
ABSTRACT 
The LH Systems ADS40 airborne digital sensor fulfils photogrammetric and remote sensing requirements. The new 
sensor is not only a camera to acquire attractive pictures: it is the next - fully digital - generation of measurement device 
for airborne photogrammetry and remote sensing. The accuracy of the lens and focal plane system under flight 
conditions (pressure and temperature) is described and a justification provided for the selection of the staggered CCD 
elements as the best choice for the customer. The electronics of the real-time data processing channel are introduced and 
the absolute signal-to-noise ratio (SNR) function of the sensor given. 
A modular, customised concept is used and the first version of the sensor has four multispectral CCD lines, which are 
selected to support both photogrammetry and remote sensing applications. The principle of achieving good colour pixel 
matching is explained. After a short description of the digital sensor's function and the technical performance, some 
application examples are shown to demonstrate the main features of the digital sensor: wide angle, high radiometric 
dynamics, high signal-to-noise-ratio, in-track stereo capability and multispectral capability. 
1 INTRODUCTION 
Assessment of a project for the customised development of the first commercial airborne digital sensor started after the 
OEEPE workshop 1994 in Paris. The goal was a complete solution to meet the requirements of photogrammetry and 
remote sensing. The two parties to the project are LH Systems and the Deutsches Zentrum für Luft- und Raumfahrt 
(German Aerospace Centre, DLR), providing a strong combination of experience of both the needs of the market and 
the technological possibilities (Sandau and Eckardt, 1996; Sandau, 1998). 
The whole development focussed on a solution that would provide final products automatically to the user. The project 
was split into four stages to ensure the quality of the digital sensor: 
(1) The functional model showed the principal SNR relations between the CCD sensor and the cost-optimised 
electronics. 
(ii) The engineering model - the first complete camera - delivered the first test results of SNR and 
photogrammetric accuracy. The results were presented at the DGPF meeting in Essen in 1999 (Reulke et al., 
1999). 
(iii) The prototype model, which incorporated the 24k CCD line, generated data sets with which to test the 
accuracy of the staggered CCD arrays. 
(iv) The series model is the final ADS40 product and incorporates the experience derived from the test results of 
the three previous models. This ensures that the customer will receive a fully tested and proven system. 
LH Systems thus offers a measurement device, in which all known errors are restricted to less than a third of a pixel. 
The user will encounter few restrictions in the use of the digital system. The system itself monitors accuracy and 
compensates for motion, air pressure and temperature. The ADS40 can work in a fully automatic mode. All camera 
specific parameters are controlled such that the user has the best SNR at the data level. For some special applications 
the customer may use control commands via the man machine interface. 
  
104 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B1. Amsterdam 2000. 
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