XVIIIth Congress: Commission VI

Kraus, Karl; Waldhäusl, Peter

Bibliographic data

Multivolume work

Persistent identifier:: 1667435949

Title:: XVIIIth Congress

Sub title:: Vienna, Austria 1996

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1667435949

Language:: English

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing

Document type:: Multivolume work

Volume

Persistent identifier:: 1677550198

Title:: Commission VI

Scope:: 149, 110, 92 Seiten

Year of publication:: 1996

Place of publication:: Vienna

Publisher of the original:: Austrian Society of Surveying and Geoinformation

Identifier (digital):: 1677550198

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(31,B6)

Language:: English

Additional Notes:: Die Vorlage enthält insgesamt 3 Werke: Commission VI (Seiten 1-149); National reports (Seiten 1-110); Special sessions (Seiten 1-92)

Other Title:: Enthaltendes Werk: National Reports; Enthaltendes Werk: Special sessions

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

Editor:: Kraus, Karl; Waldhäusl, Peter

Corporations:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Economic, Professional, and Educational Aspects of Photogrammetry and Remote Sensing

Adapter:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Economic, Professional, and Educational Aspects of Photogrammetry and Remote Sensing

Founder of work:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Economic, Professional, and Educational Aspects of Photogrammetry and Remote Sensing

Other corporate:: International Society for Photogrammetry and Remote Sensing, Congress, 18., 1996, Wien; International Society for Photogrammetry and Remote Sensing; International Society for Photogrammetry and Remote Sensing, Commission Economic, Professional, and Educational Aspects of Photogrammetry and Remote Sensing

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2019

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: Special Session

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: GEOREFERENCING REQUIREMENTS FOR AIRBORNE PHOTOGRAMMETRY AND REMOTE SENSING. Prof. em. Friedrich Ackermann [...] IUSM Working Group GPS

Document type:: Multivolume work

Structure type:: Chapter

GEOREFERENCING REQUIREMENTS FOR AIRBORNE PHOTOGRAMMETRY AND REMOTE SENSING Prof. em. Friedrich Ackermann Institute for Photogrammetry, University of Stuttgart Keplerstrasse 11, D 70174 Stuttgart Germany IUSM Working Group GPS KEY WORDS: Airborne sensor orientation, GPS, INS ABSTRACT Aur survey methods are generally moving towards multi-sensor systems, made possible by the recent technology development. Of particular importance is sensor orientation by GPS (position) and INS (attitude). Different levels of specifications are distinguished, reaching from the stabilisation and internal consistency of imaging or laser sensors to the demands on absolute orientation data for the purpose of direct georeferencing. Finally, the accuracy requirements of orientation data in combination with other sensors are reviewed. 1. CONVENTIONAL PHOTOGRAMMETRY, A MONO- SENSOR SYSTEM Aerial photogrammetry has been a mono-sensor system, for a long time, being limited to aerial photography. Because of that it was not autonomous at all, had to rely on external ground control in order to solve for the free system parameters (contrary to terrestrial photogrammetry). The application of aerial surveys has adapted to those conditions by successfully developing operational standards. The established technique and performance of aerial triangulation in particular has provided system consistence, with clear command of accuracy, reliability and economy. Various auxiliary camera orientation data from additional airborne sensors have repeatedly been considered and applied in the past, in order to ease the generally costly dependence on ground control. The efforts had only temporary success and could not basically alter the general conditions. 2. TOWARDS AUTONOMOUS MULTI-SENSOR SYSTEMS 2.1 New Technology The great advances in technology of the last two decades have started to thoroughly alter the fundamental concept and structure of photogrammetry, amounting to truly revolutionary changes. Photogrammetry is moving towards multi-sensor systems for digital information acquisition, possibly becoming nearly autonomous, i.e. practically independent of external parameter fixing. In the course of this development photogrammetry and remote sensing merge together in terms of methods, techniques and extended applications. There are 2 groups of sensor development to be distinguished, as far as photogrammetry and remote sensing are concerned: (1) Sensors providing orientation data, especially GPS, INS, and laser or radar altimeter; (2) Sensors providing multi-data about the objects, especially Laser Scanner, SAR, MS Scanner, in combination with photographic sensors or not, which in turn may become digital or linear array cameras. We concentrate here on sensors which provide orientation data, i.e. on GPS and INS in particular. 7 2.2 High Precision Kinematic GPS Positioning of Airborne Sensors 2.2.1 GPS flight navigation. First, it is to be mentioned that the C/A code pseudo-range positioning in real time has gained great influence on the navigation of air survey flights. It is practically standard, the advantages being evident. Survey flight navigation now goes by coordinates, not any more by visual navigation. As a result the photo-coverage or the flight lines of other sensors become extremely regular, with all subsequent advantages. 2.2.2 Phase Observations, Signal Loss of Lock. The real fundamental contribution of GPS concerns the high precision kinematic sensor positioning, not necessarily in real time, by differential phase observations with regard to one or more GPS ground receiver stations on known points. Prime application, so far, has been camera air station positioning for aerial triangulation, in post-processing mode. The general conditions for the application of kinematic sensor positioning are well known. They are highly favourable in general terms, advocating wide application. However, there is the problem of signal loss of lock, especially during flight turns, because the lines of sight to satellites can be interrupted by wings and fuselage. Attempts to fly turns more carefully cannot sufficiently be relied upon, and are not acceptable in operational terms. Interruption of GPS signals destroys the previous ambiguity solutions. Practicable solutions to restore or re-establish ambiguity solutions were not available, for a long time. Instead, approximate solutions were applied, based on C/A code positioning, resulting in biased ambiguity solutions, as consequence of which the following parts of the GPS trajectory showed systematic errors, called GPS drift errors. Fortunately, the drift errors turned out to be about linear for short subsequent time intervals. On that basis successful applications of kinematic GPS sensor positioning were developed, especially for aerial triangulation. The systematic GPS drift erros would be assessed and corrected for by using external information, for instance via combined adjustment in combination with photo-blocks. That type of solution and application in aerial triangulation has worked very well in practice, although some ground control points were mandatory for a datum transformation, and additional cross strips had to be applied in order to avoid system singularities. The relative precision of GPS positioning has been more than sufficient for application in all photo-scales, reaching magnitudes of < 10 cm, even « 5 cm. The limitation of the method was, however, that no absolute GPS positioning could be obtained. In combination with International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996

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