EXPERIENCES ON AUTOMATIC IMAGE MATCHING FOR DSM GENERATION
WITH ADS40 PUSHBROOM SENSOR DATA
M. Pateraki'"", E. Baltsavias!', U. Recke?
' Institute of Geodesy and Photogrammetry, ETH-Hoenggerberg, CH-8093, Zurich, Switzerland
(maria, manos)@geod.baug.ethz.ch
“Leica Geosystems GIS & Mapping GmbH, CH-9035 Heerbrugg, Switzerland
utz.recke@gis.leica-geosystems.com
Commission II, IC WG IVIV
KEY WORDS: pushbroom, sensor, systems, matching, surface, quality, analysis, performance
ABSTRACT:
This paper presents an analysis on automatic image matching for DSM generation with ADS40 airborne push-broom sensor data.
ADS40, produced by Leica Geosystems GIS & Mapping (LGGM), offers on a single camera system the possibility to acquire both
panchromatic and multispectral images in up to 10 channels (100% overlap), incorporating latest GPS and INS technology for direct
sensor orientation and latest developments in sensor technology, optics, electronics, data transfer and storage. The radiometric and
geometric characteristics of the sensor can reinforce matching in automated processes through the use of multiple channels with
small perspective distortions, direct georeferencing and superior radiometric quality. In this study, the matching performance for
DSM generation of the commercial digital photogrammetric system SOCET SET is evaluated. In addition, matching software
developed within a joint project of ETH Zurich and LGGM, making use of ADS40 special characteristics, is utilized and compared
with the above commercial system. DSM extraction is tested on rectified imagery with adjusted orientation data. The evaluation of
the matching performance is done through a qualitative and quantitative analysis in test areas in Switzerland and Japan, of different
terrain relief and land cover, as well as of different types of buildings and roofs. Results are analyzed and compared with manually
measured reference data.
1. INTRODUCTION
1.1 State-of-the-art and Proposed Evaluation
Single- and multi-line CCDs are employed as research tools in
satellite- and airborne- based sensors and are used to acquire
panchromatic and multispectral imagery in pushbroom mode for
photogrammetric and remote sensing applications. Regarding
airborne sensors, several systems have been developed and
among them fewer commercial ones, e.g. ADS40 (LGGM),
DMC (Z/1 Imaging), Starimager (Starlabo), Ultracam-D
(Vexcel). New methods, compared to the existing ones for
processing of scanned aerial films, are necessary for digital
sensors, especially line-CCD-based ones as they have
significant differences to the existing film-based cameras, e.g.
several (up to 9) CCD-lines with 100% overlap, a non-
perspective geometry in flight direction, different radiometric
characteristics, simultancous multispectral imaging capabilities,
more complicated imaging geometry and integration of
GPS/INS systems for determination of the position and
orientation of each line. Investigations regarding airborne linear-
CCDs have been already performed regarding camera
architecture, direct georeferencing, sensor modeling, ground
processing and aerial triangulation for ADS40 (Fricker, 2001;
Hinsken et al., 2002; Sandau et al., 2000; Tempelmann et al.,
2000; Tempelmann et al., 2003) and for other systems (Fritsch,
1997; Haala et al., 2000; Hoffmann et al., 2000; Leberl et al.,
2003; Tianen et al., 2003; Wewel et al., 1998). Notably fewer
studies exist on matching methods and DSM generation using
airborne linear CCDs (Gwinner et al., 1999; Neukum, 1999;
Renouard and Lehmann, 1999; Scholten, 2000). Recently, in the
" Corresponding author
402
dedicated workshop on digital aerial cameras during the Optical
3D Measurement Techniques conference in 2003, only the
papers of Nonin (2003), Pateraki and Baltsavias (2003b) and
Zhang and Gruen (2003) have been focused on automatic DSM
extraction and only the last two on algorithmic aspects.
Regarding digital photogrammetric stations, advancements in
matching for tie point extraction and DSM generation have
generally not been integrated in the current systems, although
images of different sensor orientation models, employing line
CCDs, can be imported. To date the algorithms used
traditionally for the processing of aerial frame imagery are
employed also for airborne linear CCDs.
The aim of this paper is to evaluate the matching performance
on ADS40 images, using the commercial SOCET SET digital
photogrammetric software package (from this point forward
called SS) and the matching software that has been developed at
ETH Zurich, adapted to ADS40 characteristics (from this point
forward called AIM). However, as each system employs a
different matching strategy (see Section 2), the analysis is
focused on the quality of the final product, the DSM
respectively. The quality of the extracted terrain is evaluated in
different areas of terrain relief and land-cover, using manually
measured reference data.
1.2 ADS40 and Sensor Plate Design
To date the ADS40 camera system and architecture has been
described in several publications, as mentioned already in
Section 1.1. In brief, ADS40 consists of seven parallel CCD
lines in the focal plane of a single lens system — three
panchromatic (forward-, nadir-, backward looking), red, green
and blue placed next to each other and near infrared. In addition,
ADS40 incorporates GPS and INS technology (Applanix) for
direct georeferencing.
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