REQUIREMENTS FOR NEW AIRBORNE DIGITAL SENSORS
Peter Fricker *, Alain Chapuis ", A. Stewart Walker *
* Leica Geosystems GIS & Mapping GmbH, Heinrich-Wild-Strasse, 9435 Heerbrugg, Switzerland
peter.fricker@gis.leica-geosystems.com
® Leica Geosystems GIS & Mapping GmbH, Heinrich-Wild-Strasse, 9435 Heerbrugg, Switzerland
alain.chapuis@gis.leica-geosystems.com
“ Leica Geosystems GIS & Mapping, LLC, 10840 Thornmint Road, Suite 100, San Diego, CA 92127, U.S.A.
stewart.walker(@gis.leica-geosystems.com
KEY WORDS:
Pushbroom scanner, orthorectification, frame sensor, digital mapping, urban application
ABSTRACT:
Delivery of the first production Leica ADS40 Airborne Digital Sensor took place only 8 months after it had been announced at the
ISPRS Congress in Amsterdam in July 2000. Since then over 20 units have been sold and are in constant use worldwide. Supporting
these units, which are the first of their kind, has been a major challenge for Leica Geosystems. The benefit of this support effort has
had positive aspects for both the users and the manufacturer. From the experience gained by the many users Leica Geosystems has
been able to adapt the ADS40 continuously to evolving customer needs. Most of these requirements have centered on the focal
plane. The three-line-sensor approach makes it possible to adapt this pushbroom scanner to many different needs. In particular, the
request for capability to acquire data with a smaller ground sample distance (GSD) than previously thought possible with pushbroom
scanners is investigated. It describes how careful monitoring of customer requirements and technological advances, reinforced by
focused research and development, have become the driving force in this new field of airborne digital data acquisition.
1. MODERNIZING AIRBORNE SENSORS
1.1 Introducing New Solutions into Old Technology
Photogrammetry and its contribution to our society were
defined over 100 years ago. Many discoveries and inventions
have followed. Photogrammetry is a combination of art, science
and technology, which strives to derive locations, shapes and
other information of objects from images with the best
price/accuracy ratio possible. This paper concentrates on the
way new sensors have been defined, which in the last 4 years
has caused dramatic changes in the field of airborne image
acquisition.
1.2 Totally Digital Photogrammetry — a Historic Challenge
The transition from film to digital images was an historic
challenge and a unique situation for a company renowned for
over 80 years as a developer and manufacturer of some of the
best aerial film cameras available. After designing more than 15
different aerial film cameras in the 20" century and producing
over 1200 units, of which the large number still in use
represents the backbone of mapping today, Leica Geosystems
approached the extraordinary opportunity to enter the new
millennium with a totally new challenge. For engineers
respectful of the historic legacy of Wild Heerbrugg and Leica
Geosystems, a decision to break with the past and make an
historic technological step forward in.a pivotal role was a
unique experience.
2. FORMULATING A VISION
2 Remote Sensing
Remote sensing, of which photogrammetry is an important
enabling technology, has always striven to acquire geospatial
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data, thereby overcoming limitations imposed by older
technologies. Photogrammetry based on film material as the
recording device has been one of these limitations. Satellite
platforms were the first to employ push-broom scanners to take
digital images of the earth's surface.
2.2 The First Ideas on Strip Imaging
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published in 1970 (Figure 1). Another source of information,
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