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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
