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Digital Photogrammetric cameras: a new forward looking approach 
P. Flicker, R. Sandau, P. Schreiber 
LH Systems GmbH, Heinrich-Wild-Strasse, CH-9435 Switzerland, lastname@lh-systems.com 
KEYWORDS: digital sensor, digital camera, inertial measurement, digital photogrammetry, multispectral 
imagery. 
ABSTRACT 
Airborne digital sensors are already a reality. The transition from analytical to digital photogrammetry is 
well advanced and the dividing lines between photogrammetry and remote sensing grow increasingly 
blurred. One of the advantages of direct digital data capture in the air is the possibility of capturing 
multispectral data as well as panchromatic. Between modern film-based aerial mapping cameras with their 
extremely high resolution and, at the other end of the spectrum, the high-resolution satellite sensors, the 
market for new airborne devices is large and incontestable. 
Two competing technologies are available as the basis for airborne digital sensors - linear and matrix array 
CCDs. The price/performance ratio of the matrix array CCDs are insufficient to offer swath widths and 
resolutions comparable to film cameras. The most promising alternative are linear arrays, arranged in a 
triplet on the focal plane, one forward-, one nadir- and one backward-looking. When combined with GPS 
and INS systems, this configuration provides geometric performance that enables the same photogrammetric 
operations to be performed on the workstation as with scanned film imagery. Additionally, multispectral 
CCD lines can be placed on the focal plane, providing data unique for remote sensing due to the additional 
advantages of geometrically correct sensor modeling, stereo imagery and accurate geo-coding. 
A development project between LH Systems and the German Aerospace Centre has resulted in a functioning 
three-line sensor. An engineering model is being flown successfully and a production model is scheduled for 
market introduction in summer 2000 at the ISPRS congress in Amsterdam. 
1. INTRODUCTION 
LH Systems’ announcement at the end of 1998 that 
an engineering model of their forthcoming airborne 
digital sensor had been flown successfully implies 
that a genuine alternative to the familiar aerial film 
camera is imminent. 
Except for producing stereoscopes, LH Systems and 
its predecessor Leica were never active in image 
interpretation. Yet this new sensor will have 
multispectral lines on the focal plane: it will be 
capable of generating precise, geometric 
information about the surface of the earth, but will 
also produce data amenable to proven remote 
sensing techniques. It will further soften the 
demarcation between photogrammetry and remote 
sensing and accelerate the decline of the photo 
laboratory, as digital image data can be transferred 
from the aircraft directly to the workstation. 
The debate about airborne versus spaceborne 
imagery continues. The highest resolution 
applications, with ground pixel sizes in the one 
centimetre to one decimetre level, are likely to 
remain the province of the film camera. Yet there is 
a huge, pent up demand for top quality, 
multispectral information in the gap between this 
and the one metre and coarser resolutions offered by 
the satellite operators. Both spaceborne and airborne