Proceedings International Workshop on Mobile Mapping Technology

li, rongxing

Bibliographic data

Monograph

Persistent identifier:: 856671290

Author:: Li, Rongxing

Title:: Proceedings International Workshop on Mobile Mapping Technology

Sub title:: April 21 - 23, 1999, Bangkok, Thailand

Scope:: 1 Online-Ressource (Getr. Zählung [ca. 400 Seiten])

Year of publication:: 1999

Place of publication:: London

Publisher of the original:: RICS Books

Identifier (digital):: 856671290

Illustration:: Illustrationen, Diagramme, Karten

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: [Session 4: Sensor Integration and Calibration]

Document type:: Monograph

Structure type:: Chapter

Chapter

Title:: SENSOR INTEGRATION AND CALIBRATION OF DIGITAL AIRBORNE THREE-LINE CAMERA SYSTEMS. Michael Cramer, Dirk Stallmann and Norbert Haala.

Document type:: Monograph

Structure type:: Chapter

4-5-1 SENSOR INTEGRATION AND CALIBRATION OF DIGITAL AIRBORNE THREE-LINE CAMERA SYSTEMS Michael Cramer, Dirk Stallmann and Norbert Haala Institute for Photogrammetry (ifp), University of Stuttgart Geschwister-Scholl-Straße 24D, 70174 Stuttgart / Germany e-mail: Michael.Cramer@ifp.uni-stuttgart.de Commission II, Working Group 1 KEY WORDS: GPS, INS, aerial triangulation, push-broom line scanners ABSTRACT The determination of the exterior orientation parameters is an essential pre-requisite for the evaluation of any imagery from terrestrial, airborne or satellite based sensors. Normally, this georeferencing processing is solved indirectly by using a number of well known ground control points and their corresponding image coordinates. Using a mathematical model for the relation between image and object space the exterior orientations can be calculated and the local image coordinates are related to the global ground coordinate system. In principle this approach can be applied for georeferencing of push-broom line scanner imagery, but this process is highly inefficient. Due to the large number of unknowns a large number of tie and control points is necessary for orientation determination. To allow an operational processing the direct measurement of exterior orientation using GPS and INS and additional information is inevitable. Within this article the geometric processing of high resolution line scanner imagery is described and the test results from different airborne test flights flown in 1998 are given. KURZFASSUNG Die Bestimmung der Parameter der äußeren Orientierung ist eine wichtige Voraussetzung für die Auswertung terrestrischer, luft- oder weltraumgestützter Bilddaten. Normalenweise wird diese Georeferenzierung indirekt durch die Verwendung bekannter Paßpunktinforma tionen am Boden und die Messung der zugehörigen Bildkoordinaten gelöst. Unter Verwendung eines mathematischen Modells für die die Beziehung zwischen Bild- und Objektraum können die äußeren Orientierungen berechnet und die lokalen Bildkoordinaten in Bezug zu dem globalen Geländekoordinatensystem gebracht werden. Prinzipiell ist dieser Ansatz der Georefernzierung auch auf Pushbroom- Zeilenscanner-Daten übertragbar, allerdings ist dieser Prozeß hochgradig ineffizient. Wegen der hohen Anzahl von Unbekannten wird für die Orientierungsbestimmung eine große Zahl von Verknüpfungs- und Paßpunkten benötigt. Im Hinblick auf eine operationeile Ve rarbeitung der Daten ist daher die direkte Messung der äußeren Orientierung mittels GPS, INS und weiteren Sensoren unvermeid bar. In diesem Artikel werden die geometrische Auswertung hochaufgelöster Zeilenscanner-Daten beschrieben und die Ergebnisse verschiedener 1998 durchgeführter Testflüge vorgestellt. 1 INTRODUCTION Up to now the analogue acquisition of image data prevents pho togrammetry to become a fully digital, towards real time mapping system. Todays systems for digital airborne image acquisition can be split into frame and push-broom systems. Despite the ongo ing progress in the development of airborne frame cameras it still seems to take some more years to replace the large format film based cameras with equivalently sized digital frame systems. The maximum resolution of digital frame sensors available is about 9000 x 9000 pixel. Assuming 10^m pixel size, this sensor cov ers about 80cm 2 , which is still significantly less compared to the standard photogrammetric analogue image format of 23 x 23cm 2 . Today, digital systems using the line scanning geometry are the only imaging sensors that can compete with digitized aerial photos in terms of acquired area and image resolution. These line scanners can be expanded to multi-line sensors provid ing stereoscopic and multi-spectral data simultaneously. These are enormous advantages compared to traditional analogue data. Un fortunately line scanning systems are affected by one major fact: Georeferencing of image data is more complex compared to stan dard aerial triangulation. Although the traditional indirect approach using ground control points for the determination of the exterior orientation of the images works for airborne sensors, this process is highly inefficient. For line scanner systems a direct processing strategy utilizing direct measurements of the exterior orientation provided by satellite (GPS) and inertial navigation system (INS) is necessary for operational and efficient data evaluation. Even though direct georeferencing is no must for digital frame cameras a GPS/INS component is also included in some systems (Toth, 1998). Within this article the integration of GPS, INS and line scanning imagery for the georeferencing of a digital airborne line camera system is shown. Following a short discussion of different ap proaches of georeferencing of image data the combined approach using GPS, INS and measurements from image space in an ex tended aerial triangulation process is described (section 3). Com pared to the stand-alone GPS/INS integration the combination with image observations increases the reliability of the whole sensor system. Remaining systematic effects can be modeled using addi tional parameters similar to self-calibration. Furthermore, the pho togrammetric constraints are used to eliminate the systematic INS error effects significantly. The influence of the different error types which are introduced with the different sensors are shown. Special focus is given on the effects caused by systematic INS errors. The influence of these errors is shown in some simulations (section 4). In the last part the functionality of the combined aerial triangulation algorithmn is presented. The practical results of different testflights using different camera systems over a well known testfield close to Stuttgart/Germany with more than 150 signalized check points on the ground are given. 2 PRINCIPLES OF GEOREFERENCING OF IMAGERY The determination of the exterior orientations is a major task in the evaluation procedure of image data and can be done using different orientation methods. These methods can be classified in indirect- or direct approaches and are applicable for traditional frame (digital/analogue) or line imagery. Table 1 gives a short

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