International Society of Photogrammetry and Remote Sensing (ISPRS)

Background – Status of Science and Technology

The use of high resolution earth observation systems for mapping made large progress. Several optical space borne sensors are available now and additional systems will come in near future. There are different geometric models for handling the variety of image products; some are rigorous, some are based on approximations, some do use available sensor orientation parameters and some do not. The optimal solution in relation to the given conditions has to be identified, respecting also possible problems of the images and sensor parameters. Especially the orientation with a limited number of not well distributed control points or even without control points has to be investigated. 2- and 3-line sensors do allow a check or an improvement of the orientation data just by means of tie points; the advantage of these stereo systems against the satellites with flexible view direction has to be investigated.

From the largest part of the world the height information is available from the SRTM-mission free of charge. These DEMs do have a spacing of 3”, sufficient for several applications. Limitations are in especially mountainous areas where the spacing does not guarantee the full morphologic information; in addition the accuracy is not so good in inclined areas up to gaps caused by Radar lay over. Of course also in steep areas DEMs based on optical space images do have some limitations what has to be analysed in detail depending upon the used matching technique. The simple height accuracy relation just as a linear function of the height to base relation is valid only for flat and open areas with sufficient contrast. The optimal height to base relation has to be identified for different terrain types including also build up areas. This has to respect also the influence of not close to synchronous imaging causing radiometric differences based on changes in the object space and different length of shadows.

The geometric models and the generated DEMs have to be verified by independent reference data. An overview of available test sites shall be generated.

Terms of reference:    

• 1. Comparison of existing and evolving algorithms for geometrical modelling of space images under operational conditions including direct georeferencing capabilities and special conditions for 2- and 3- line sensors;
• 2. Extrapolation of the previous comparisons (outside the area of the control points), analysis and report for each space imaging system;
• 3. Intensified and detailed study on the accuracy and cost effectiveness of various DEM data acquisition techniques;
• 4. Identification and cataloguing of international test sites for inter-comparison and evaluation of different DEM acquisition methods based on space information ;
• 5. Geometric quality requirements for advanced optical systems derived DEM.

Commission I Terms of Reference to be addressed:   

• a) Design and realization of digital aerial and spaceborne missions for Earth observation;
• b) Design, construction, characterization, and installation of imaging and non-imaging   sensors (including Optical, IR, SAR, IFSAR, LIDAR, etc.)
• e) Geometric and radiometric properties, quality standards, and factors affecting data quality;
• g) Integrated platform guidance, navigation, positioning and orientation;
• h) Data reception and pre-processing;
• j) Systems and media for recording sensor data, auxiliary data (time, position, attitude, etc.) and film scanners;
• k) Image and non-image data transfer standards.

ISPRS Resolutions to be handled:
 
I.3  Geometric Handling of Space Images

• existing and evolving algorithms be compared under operational conditions;
• the results of the comparisons be extrapolated (outside the area of control points), analyzed, and reported for each space imaging system.

I.5  DTM Data Acquisition Quality

• an intensified, detailed study be conducted on the accuracy and cost effectiveness of various sensors and techniques;
• international test sites be identified and catalogued for inter-comparison and evaluation of different methods;
• quality standards be developed for advanced optical and active microwave system-derived DTMs.

 WG-officers and members:

Chair:       Dr. Karsten Jacobsen
Institute of Photogrammetry and GeoInformation
University of Hannover
Nienburger Str. 1
D-30167 Hannover - Germany
phone   +49 (0) 511 762 2485,  fax  +49 (0) 511 762 2483
Email: jacobsen
www.ipi.uni-hannover.de

Co-Chair:   Dr. Peter Reinartz 
DLR
Institut für Methodik der Fernerkundung
Bildwissenschaften
D-82234 Oberpfaffenhofen, Post Wessling, Germany
phone +49 (0) 8153 282757,   fax  +49 (0) 8153 281444
E-mail: peter.reinartzdlr.de
www.dlr.de

Second Co-Chair:  Daniela Poli
CyberCity AG
Schaffhauser Str.481
P.O. Box
CH-8052 Zurich
Switzerland

Secretary: Dr. Gürcan Büjüksalih
BIMTAS
Tophanelioglu Cad.
ISKI Hizmit Binasi No. 62K.3-4
34460 Altunizade-Istanbul, Turkey
phone: +90 216 4749915-301 fax: +90 216 4749930
E-mail: gbuyuksalih@yahoo.com

Meeting

ISPRS Hannover Workshop 2007
High-Resolution Earth Imaging for Geospatial Information

Hannover, Germany, May 29 – June 1, 2007

 PROCEEDINGS