Timm Ohlhof - Academia.edu (original) (raw)

Papers by Timm Ohlhof

This paper describes the process of photogrammetric point determination by bundle adjustment usin... more This paper describes the process of photogrammetric point determination by bundle adjustment using three-line imagery collected by MOMS-2P, the German Modular Optoelectronic Multispectral Scanner. Since May 1996 MOMS-2P is attached to the remote sensing module PRIRODA of the Russian space station MIR. Its stereo module with three differently oriented lenses allows for the acquisition of three-fold along track stereoscopic imagery. The forward and aft looking channels provide 18 m, the nadir looking high resolution (HR) channel 6 m ground pixel size. For the photogrammetric evaluation 9 image scenes of orbit T083C were composed to an approximately 415 km long image strip covering parts of Southern Germany and Austria. For the German part control points provided by AMilGeo (Amt für Militärisches Geowesen) were used as ground control, with an accuracy of 1.5 m in X, Y and Z. The navigation data are recorded simultaneously with the image lines by the MOMS-NAV package mounted next to MOM...

The paper deals with the photogrammetric point determination using digital images of the asteroid... more The paper deals with the photogrammetric point determination using digital images of the asteroid 243 Ida, which were acquired during the second asteroid flyby of the Galileo spacecraft in August 1993. The photogrammetric point determination was carried out with three different methods: Forward intersections assuming error-free orientation parameters, bundle adjustment without orbital constraints, and bundle adjustment including orbital constraints. The forward intersections lead to poor results, since, in fact, the orientation parameters of the images are not error-free. Thus the functional model has significant systematic errors. Much better results could be achieved by the conventional bundle adjustment, where the exterior orientation parameters were treated as unknowns in the collinearity equations and, in addition, introduced as direct observations. The best results were obtained from the bundle adjustment with orbital constraints. This approach guarantees that all exposure sta...

Earth observation is a fundamental source of information in today’s society. A multitude of space... more Earth observation is a fundamental source of information in today’s society. A multitude of spaceborne and airborne sensors collect daily an enormous amount of information in the form of imagery of the earth. It is evident that systematic approaches for information mining in such imagery are required. New sensors and image processing techniques extend the image information base as well as improve quality and speed of availability. In this paper we give information on a new, European, high-resolution optical sensor, which is currently implemented for airborne use and will contribute to geo-referenced earth observation. The project includes also a new approach for image processing. Via parallel computing for the purpose of fully automated generation of digital surface models and orthomosaics, fundamental geometric and visual geoinformation is built up. All of this would be cumbersome without a metadata information system, which allows for archiving and retrieval, dissemination and wor...

The most advanced camera concept makes use of 3 linear CCD arrays. Stereo images are acquired qua... more The most advanced camera concept makes use of 3 linear CCD arrays. Stereo images are acquired quasi simultaneously while the camera platform is moving. The mathematical model of photogrammetric point determination is based on a polynomial approach in case of airborne imagery, whereas orbital constraints should be utilized in case of spaceborne imagery. Computer simulations on point determination have turned out that the most accurate results can be obtained by simultaneous block adjustment of multiple overlapping and additional crossing strips. The usefulness of the 3-line camera concept and the applicability of the proposed mathematical models of point determination have been proven with practical airborne MEOSS and spaceborne MOMS-02 imagery. For both MEOSS and MOMS-02 imagery, empirical accuracies in object space of 1 pixel or better in planimetry and height were obtained as verified by independent check points. 1. THREE-LINE CAMERAS With the introduction of digital image process...

The goal of the project was to establish an operational workflow to update existing VMap Level 1 ... more The goal of the project was to establish an operational workflow to update existing VMap Level 1 data using commercially available satellite imagery. The workflow developed uses both optical and SAR imagery. First, the images are radiometrically enhanced and geocoded. In the second step, different methods for the automatic extraction of area, line and point features are applied. After a raster-vector-conversion, the attributes of the features are assigned interactively. The next step is the GIS validation process, where complex polygons are resolved and the data structure of all features and attributes is checked. The focal point of the update procedure is a semi-automatic feature linking process of the existing VMap1 data and the newly extracted topographic features. This process determines the likeness of linked or unlinked features based on geometry, feature class, attributes and topology. The result of the update procedure is an up-to-date VMap1 data set. The complete workflow w...

The emphasis of that paper is point determination using spaceborne 3-line imagery and orbital con... more The emphasis of that paper is point determination using spaceborne 3-line imagery and orbital constraints. In order to properly utilize the image information contained in conjugate point coordinates and the orbit information contained in tracking data, both data types have to be evaluated in a combined adjustment process. To this end, the conventional bundle block adjustment algorithm is supplemented by a rigorous dynamical modeling of the satellite motion to take orbital constraints into account. For the forthcoming Mars96 HRSC/WAOSS experiment computer simulations on point determination have been performed to obtain a survey of the attainable accuracy at local, regional and global levels. Since WAOSS will image the entire planet, a closed block covering the entire Martian surface may be processed under ideal circumstances. Because of the extraordinary strength of the closed block and based on the complete image, orbit, attitude and ground control information, 60 m accuracy in X, Y...

Photogrammetric Engineering and Remote Sensing, 2000

This paper deals with the recomputation of the global controlpoint network of the planet Mars. Th... more This paper deals with the recomputation of the global controlpoint network of the planet Mars. The existing Mars control point net is based on Viking data and consists of a large number of ground points, which can be easily identifed in the imagery and whose three-dimensional (30) object coordinates (e.g., latitude p , longitude A, and height h with respect to a reference ellipsoid) are known. These coordinates were redetermined in order to eliminate several disadvantages of the former computations and to include the currently best available input data such as improved Viking trajectory information, the Viking occultation data, present rotational parameters, and the Mars Pathfinder lander data. Within a simultaneous 30 bundle block triangulation, seven interior orientation parameters, the position and attitude pammeters of 1140 images, and the ground coordinates of 3739 tie points and one control point were estimated. The RMS values CLJ~, , q , J. Q of the theoretical standard deviations of the adjusted object coordinates amount to 750 m, 770 m, and 710 m, respectively, which is a significant improvement compared with former results (1 to 5 km). The accuracy of the ground point coordinates is close to the theoretical accuracy limit of 520 m in X, Y, and Z, where error-free orientation parameters are assumed. This new set of orientation parameters and ground points may now be used for local, regional, and global DTM genemtion; for the determination of reference bodies; for mapping purposes; as well as for current (Mars Global Surveyor 1996) and future (e.g.

Theory and Applications of Knowledge Driven Image Information Mining With Focus on Earth Observation, Sep 1, 2004

Earth observation is a fundamental source of information in today's society. A multitude of ... more Earth observation is a fundamental source of information in today's society. A multitude of spaceborne and airborne sensors collect daily an enormous amount of information in the form of imagery of the earth. It is evident that systematic approaches for information mining in such imagery are required. New sensors and image processing techniques extend the image information base as well as improve quality and speed of availability. In this paper we give information on a new, European, high-resolution optical sensor, which is currently implemented for airborne use and will contribute to geo-referenced earth observation. The project includes also a new approach for image processing. Via parallel computing for the purpose of fully automated generation of digital surface models and orthomosaics, fundamental geometric and visual geoinformation is built up. All of this would be cumbersome without a metadata information system, which allows for archiving and retrieval, dissemination and workflow management. Thus, the paper presents aspects of image generation as well as aspects of image information mining.

Lunar and Planetary Science Conference, Feb 28, 1996

This paper deals with the computation of a new global control point network of the planet Mars. T... more This paper deals with the computation of a new global control point network of the planet Mars. The existing Mars control point net is based on Viking data and consists of a large number of ground points, which can be easily identified in the imagery and whose 3-dimensional object coordinates (e.g. latitude ', longitude and height h w.r.t. a reference ellipsoid) are known. These coordinates were now determined again to eliminate several disadvantages of former computations and to include the currently best available input data like improved Viking trajectory information, the Viking occultation data, present rotational parameters and the Mars Pathfinder lander. Within a simultaneous 3D bundle block triangulation, 7 interior orientation parameters, the position and attitude parameters of 1140 images and the ground coordinates of 3739 tie points and 1 control point were estimated. The rms values X, Ŷ , Ẑ of the theoretical standard deviations of the adjusted object coordinates amount to 750 m, 770 m and 710 m, which is a significant improvement compared with former results (1-5 km). The accuracy of the ground point coordinates is close to the theoretical accuracy limit of 520 m in X Y and Z, where error-free orientation parameters are assumed. This new set of orientation parameters and ground points may now be used for local, regional and global DTM generation, the determination of reference bodies, mapping purposes as well as for current (Mars Global Surveyor 1996) and future (e.g.

As part of the 2nd German Spacelab misssion (D2) the MOMS-02 scanner has collected high-resolutio... more As part of the 2nd German Spacelab misssion (D2) the MOMS-02 scanner has collected high-resolution images with 5 m and 14 m ground pixel size. Based on a 3-line CCD-concept, direct and simultaneous stereo imaging is enabled through nadir, forward, and backward looking CCD lines, that allow to view terrestrial at different aspect angles. Given the known camera position and orientation, the ground position of object points can be determined from MOMS-02 images within the stereoscopic evaluation. In extension of current photogrammmetric algorithms a combined approach to orbit determination and photogrammmetric restitution has been developed, which allows the simultaneous adjustment of orbital parameters and ground coordinates.To this end, the spacecraft trajectory and the covariance matrix from the orbit determination process are incorporated into the photogrammetric processing with associated partial derivatives of spacecraft positionwith respect to epoch state and model parameters. S...

A new approach to photogrammetric restitution of 3-line stereo scanner images is presented for us... more A new approach to photogrammetric restitution of 3-line stereo scanner images is presented for use within the MOMS-02 and MOMS-2P project. It is based on the replacement of the orientation image concept by a rigorous treatment of the orbit information in the bundle adjustment process. To this end, the trajectory data and the orbit determination parameter covariance matrix are incorporated into the photogrammetric processing, together with associated partial derivatives of the spacecraft position with respect to the epoch state and model parameters. By constraining the adjusted trajectory to the physical laws of orbital motion, the bundle adjustment process is stabilized by a significant reduction of the number of required destimation parameters. The basic algorithms for the incorporation of orbital constraints into the photometric evaluation of stereo scanner images and the resulting benefits are described. Special focus is given to the application for MOMS-02 image analysis and nec...

One of the main topics in photogrammetry is the development of automatic processing techniques, e... more One of the main topics in photogrammetry is the development of automatic processing techniques, e.g. for aerotriangulation and stereo restitution, both starting from digital aerial imagery. On the other hand digital cameras and sensors gain more and more importance. One of the most promising sensor concept makes use of three linear CCD arrays. This paper deals with the special geometry of 3-line imagery and the consequences for the processing on a digital photogrammetric workstation.

The emphasis of that paper is point determination using spaceborne 3-line imagery and orbital con... more The emphasis of that paper is point determination using spaceborne 3-line imagery and orbital constraints. In order to properly utilize the image information contained in conjugate point coordinates and the orbit information contained in tracking data, both data types have to be evaluated in a combined adjustment process. To this end, the conventional bundle block adjustment algorithm is supplemented by a rigorous dynamical modeling of the satellite motion to take orbital constraints into account. For the forthcoming Mars96 HRSC/WAOSS experiment computer simulations on point determination have been performed to obtain a survey of the attainable accuracy at local, regional and global levels. Since WAOSS will image the entire planet, a closed block covering the entire Martian surface may be processed under ideal circumstances. Because of the extraordinary strength of the closed block and based on the complete image, orbit, attitude and ground control information, 60 m accuracy in X, Y...

The most advanced camera concept makes use of 3 linear CCD arrays. Stereo images are acquired qua... more The most advanced camera concept makes use of 3 linear CCD arrays. Stereo images are acquired quasi simultaneously while the camera platform is moving. The mathematical model of photogrammetric point determination is based on a polynomial approach in case of airborne imagery, whereas orbital constraints should be utilized in case of spaceborne imagery. Computer simulations on point determination have turned out that the most accurate results can be obtained by simultaneous block adjustment of multiple overlapping and additional crossing strips. The usefulness of the 3-line camera concept and the applicability of the proposed mathematical models of point determination have been proven with practical airborne MEOSS and spaceborne MOMS-02 imagery. For both MEOSS and MOMS-02 imagery, empirical accuracies in object space of 1 pixel or better in planimetry and height were obtained as verified by independent check points. 1. THREE-LINE CAMERAS

In the course of the 2nd German Spacelab mission D2, scheduled for launch in 1993, the MOMS-02 ca... more In the course of the 2nd German Spacelab mission D2, scheduled for launch in 1993, the MOMS-02 camera is intended to acquire digital threefold stereo imagery of the earth's surface from space. In former simulations the influence of certain mission parameters on the attainable geometric accuracy has already been examined. With regard to the future compilation of real data, the functional model was extended with respect to the special MOMS-02 camera geometry and the actual orbit. After a brief description of the extended model, the results of new simulations are presented. They show the influence of the precision of observed exterior orientation parameters, the type and density of ground control, the camera inclination across flight direction and the simultaneous adjustment of two crossing strips with different intersection angles on the theoretical accuracy of the point determination. Because of the improved functional model the obtained accuracy estimates are expected to be repr...

We performed a photogrammetric evaluation of 36 images of Ida and its satellite, obtained by the ... more We performed a photogrammetric evaluation of 36 images of Ida and its satellite, obtained by the Galileo SSI camera during the flyby inAug. 1993 with the goal to determine the size, global shape, and, possibly, mass of the asteroid. In the first approach of our analysis we considered the rotational elements of Ida, the position of its moon, and the spacecraft trajectory to be fixed. Only camera pointingdata and image coordinates were included as estimation parameters in the adjustment procedure. We obtained (1) a dense network of ground points, (2) high-resolution terrain models in selected regions of Ida, (3) the mean position of Ida's moon at the time of the Galileo flyby. Determining the orbital motion of the small satellite is crucial, as this will offer the unique opportunity to determine the mass and density of Ida. The digital terrain models obtained in this study will be used to produce color ortho images (rectified images) for spectrophotometric analyses.

This paper describes the process of photogrammetric point determination by bundle adjustment usin... more This paper describes the process of photogrammetric point determination by bundle adjustment using three-line imagery collected by MOMS-2P, the German Modular Optoelectronic Multispectral Scanner. Since May 1996 MOMS-2P is attached to the remote sensing module PRIRODA of the Russian space station MIR. Its stereo module with three differently oriented lenses allows for the acquisition of three-fold along track stereoscopic imagery. The forward and aft looking channels provide 18 m, the nadir looking high resolution (HR) channel 6 m ground pixel size. For the photogrammetric evaluation 9 image scenes of orbit T083C were composed to an approximately 415 km long image strip covering parts of Southern Germany and Austria. For the German part control points provided by AMilGeo (Amt für Militärisches Geowesen) were used as ground control, with an accuracy of 1.5 m in X, Y and Z. The navigation data are recorded simultaneously with the image lines by the MOMS-NAV package mounted next to MOM...

The paper deals with the photogrammetric point determination using digital images of the asteroid... more The paper deals with the photogrammetric point determination using digital images of the asteroid 243 Ida, which were acquired during the second asteroid flyby of the Galileo spacecraft in August 1993. The photogrammetric point determination was carried out with three different methods: Forward intersections assuming error-free orientation parameters, bundle adjustment without orbital constraints, and bundle adjustment including orbital constraints. The forward intersections lead to poor results, since, in fact, the orientation parameters of the images are not error-free. Thus the functional model has significant systematic errors. Much better results could be achieved by the conventional bundle adjustment, where the exterior orientation parameters were treated as unknowns in the collinearity equations and, in addition, introduced as direct observations. The best results were obtained from the bundle adjustment with orbital constraints. This approach guarantees that all exposure sta...

Earth observation is a fundamental source of information in today’s society. A multitude of space... more Earth observation is a fundamental source of information in today’s society. A multitude of spaceborne and airborne sensors collect daily an enormous amount of information in the form of imagery of the earth. It is evident that systematic approaches for information mining in such imagery are required. New sensors and image processing techniques extend the image information base as well as improve quality and speed of availability. In this paper we give information on a new, European, high-resolution optical sensor, which is currently implemented for airborne use and will contribute to geo-referenced earth observation. The project includes also a new approach for image processing. Via parallel computing for the purpose of fully automated generation of digital surface models and orthomosaics, fundamental geometric and visual geoinformation is built up. All of this would be cumbersome without a metadata information system, which allows for archiving and retrieval, dissemination and wor...

The most advanced camera concept makes use of 3 linear CCD arrays. Stereo images are acquired qua... more The most advanced camera concept makes use of 3 linear CCD arrays. Stereo images are acquired quasi simultaneously while the camera platform is moving. The mathematical model of photogrammetric point determination is based on a polynomial approach in case of airborne imagery, whereas orbital constraints should be utilized in case of spaceborne imagery. Computer simulations on point determination have turned out that the most accurate results can be obtained by simultaneous block adjustment of multiple overlapping and additional crossing strips. The usefulness of the 3-line camera concept and the applicability of the proposed mathematical models of point determination have been proven with practical airborne MEOSS and spaceborne MOMS-02 imagery. For both MEOSS and MOMS-02 imagery, empirical accuracies in object space of 1 pixel or better in planimetry and height were obtained as verified by independent check points. 1. THREE-LINE CAMERAS With the introduction of digital image process...

The goal of the project was to establish an operational workflow to update existing VMap Level 1 ... more The goal of the project was to establish an operational workflow to update existing VMap Level 1 data using commercially available satellite imagery. The workflow developed uses both optical and SAR imagery. First, the images are radiometrically enhanced and geocoded. In the second step, different methods for the automatic extraction of area, line and point features are applied. After a raster-vector-conversion, the attributes of the features are assigned interactively. The next step is the GIS validation process, where complex polygons are resolved and the data structure of all features and attributes is checked. The focal point of the update procedure is a semi-automatic feature linking process of the existing VMap1 data and the newly extracted topographic features. This process determines the likeness of linked or unlinked features based on geometry, feature class, attributes and topology. The result of the update procedure is an up-to-date VMap1 data set. The complete workflow w...

The emphasis of that paper is point determination using spaceborne 3-line imagery and orbital con... more The emphasis of that paper is point determination using spaceborne 3-line imagery and orbital constraints. In order to properly utilize the image information contained in conjugate point coordinates and the orbit information contained in tracking data, both data types have to be evaluated in a combined adjustment process. To this end, the conventional bundle block adjustment algorithm is supplemented by a rigorous dynamical modeling of the satellite motion to take orbital constraints into account. For the forthcoming Mars96 HRSC/WAOSS experiment computer simulations on point determination have been performed to obtain a survey of the attainable accuracy at local, regional and global levels. Since WAOSS will image the entire planet, a closed block covering the entire Martian surface may be processed under ideal circumstances. Because of the extraordinary strength of the closed block and based on the complete image, orbit, attitude and ground control information, 60 m accuracy in X, Y...

Photogrammetric Engineering and Remote Sensing, 2000

This paper deals with the recomputation of the global controlpoint network of the planet Mars. Th... more This paper deals with the recomputation of the global controlpoint network of the planet Mars. The existing Mars control point net is based on Viking data and consists of a large number of ground points, which can be easily identifed in the imagery and whose three-dimensional (30) object coordinates (e.g., latitude p , longitude A, and height h with respect to a reference ellipsoid) are known. These coordinates were redetermined in order to eliminate several disadvantages of the former computations and to include the currently best available input data such as improved Viking trajectory information, the Viking occultation data, present rotational parameters, and the Mars Pathfinder lander data. Within a simultaneous 30 bundle block triangulation, seven interior orientation parameters, the position and attitude pammeters of 1140 images, and the ground coordinates of 3739 tie points and one control point were estimated. The RMS values CLJ~, , q , J. Q of the theoretical standard deviations of the adjusted object coordinates amount to 750 m, 770 m, and 710 m, respectively, which is a significant improvement compared with former results (1 to 5 km). The accuracy of the ground point coordinates is close to the theoretical accuracy limit of 520 m in X, Y, and Z, where error-free orientation parameters are assumed. This new set of orientation parameters and ground points may now be used for local, regional, and global DTM genemtion; for the determination of reference bodies; for mapping purposes; as well as for current (Mars Global Surveyor 1996) and future (e.g.

Theory and Applications of Knowledge Driven Image Information Mining With Focus on Earth Observation, Sep 1, 2004

Earth observation is a fundamental source of information in today's society. A multitude of ... more Earth observation is a fundamental source of information in today's society. A multitude of spaceborne and airborne sensors collect daily an enormous amount of information in the form of imagery of the earth. It is evident that systematic approaches for information mining in such imagery are required. New sensors and image processing techniques extend the image information base as well as improve quality and speed of availability. In this paper we give information on a new, European, high-resolution optical sensor, which is currently implemented for airborne use and will contribute to geo-referenced earth observation. The project includes also a new approach for image processing. Via parallel computing for the purpose of fully automated generation of digital surface models and orthomosaics, fundamental geometric and visual geoinformation is built up. All of this would be cumbersome without a metadata information system, which allows for archiving and retrieval, dissemination and workflow management. Thus, the paper presents aspects of image generation as well as aspects of image information mining.

Lunar and Planetary Science Conference, Feb 28, 1996

This paper deals with the computation of a new global control point network of the planet Mars. T... more This paper deals with the computation of a new global control point network of the planet Mars. The existing Mars control point net is based on Viking data and consists of a large number of ground points, which can be easily identified in the imagery and whose 3-dimensional object coordinates (e.g. latitude ', longitude and height h w.r.t. a reference ellipsoid) are known. These coordinates were now determined again to eliminate several disadvantages of former computations and to include the currently best available input data like improved Viking trajectory information, the Viking occultation data, present rotational parameters and the Mars Pathfinder lander. Within a simultaneous 3D bundle block triangulation, 7 interior orientation parameters, the position and attitude parameters of 1140 images and the ground coordinates of 3739 tie points and 1 control point were estimated. The rms values X, Ŷ , Ẑ of the theoretical standard deviations of the adjusted object coordinates amount to 750 m, 770 m and 710 m, which is a significant improvement compared with former results (1-5 km). The accuracy of the ground point coordinates is close to the theoretical accuracy limit of 520 m in X Y and Z, where error-free orientation parameters are assumed. This new set of orientation parameters and ground points may now be used for local, regional and global DTM generation, the determination of reference bodies, mapping purposes as well as for current (Mars Global Surveyor 1996) and future (e.g.

As part of the 2nd German Spacelab misssion (D2) the MOMS-02 scanner has collected high-resolutio... more As part of the 2nd German Spacelab misssion (D2) the MOMS-02 scanner has collected high-resolution images with 5 m and 14 m ground pixel size. Based on a 3-line CCD-concept, direct and simultaneous stereo imaging is enabled through nadir, forward, and backward looking CCD lines, that allow to view terrestrial at different aspect angles. Given the known camera position and orientation, the ground position of object points can be determined from MOMS-02 images within the stereoscopic evaluation. In extension of current photogrammmetric algorithms a combined approach to orbit determination and photogrammmetric restitution has been developed, which allows the simultaneous adjustment of orbital parameters and ground coordinates.To this end, the spacecraft trajectory and the covariance matrix from the orbit determination process are incorporated into the photogrammetric processing with associated partial derivatives of spacecraft positionwith respect to epoch state and model parameters. S...

A new approach to photogrammetric restitution of 3-line stereo scanner images is presented for us... more A new approach to photogrammetric restitution of 3-line stereo scanner images is presented for use within the MOMS-02 and MOMS-2P project. It is based on the replacement of the orientation image concept by a rigorous treatment of the orbit information in the bundle adjustment process. To this end, the trajectory data and the orbit determination parameter covariance matrix are incorporated into the photogrammetric processing, together with associated partial derivatives of the spacecraft position with respect to the epoch state and model parameters. By constraining the adjusted trajectory to the physical laws of orbital motion, the bundle adjustment process is stabilized by a significant reduction of the number of required destimation parameters. The basic algorithms for the incorporation of orbital constraints into the photometric evaluation of stereo scanner images and the resulting benefits are described. Special focus is given to the application for MOMS-02 image analysis and nec...

One of the main topics in photogrammetry is the development of automatic processing techniques, e... more One of the main topics in photogrammetry is the development of automatic processing techniques, e.g. for aerotriangulation and stereo restitution, both starting from digital aerial imagery. On the other hand digital cameras and sensors gain more and more importance. One of the most promising sensor concept makes use of three linear CCD arrays. This paper deals with the special geometry of 3-line imagery and the consequences for the processing on a digital photogrammetric workstation.

The emphasis of that paper is point determination using spaceborne 3-line imagery and orbital con... more The emphasis of that paper is point determination using spaceborne 3-line imagery and orbital constraints. In order to properly utilize the image information contained in conjugate point coordinates and the orbit information contained in tracking data, both data types have to be evaluated in a combined adjustment process. To this end, the conventional bundle block adjustment algorithm is supplemented by a rigorous dynamical modeling of the satellite motion to take orbital constraints into account. For the forthcoming Mars96 HRSC/WAOSS experiment computer simulations on point determination have been performed to obtain a survey of the attainable accuracy at local, regional and global levels. Since WAOSS will image the entire planet, a closed block covering the entire Martian surface may be processed under ideal circumstances. Because of the extraordinary strength of the closed block and based on the complete image, orbit, attitude and ground control information, 60 m accuracy in X, Y...

The most advanced camera concept makes use of 3 linear CCD arrays. Stereo images are acquired qua... more The most advanced camera concept makes use of 3 linear CCD arrays. Stereo images are acquired quasi simultaneously while the camera platform is moving. The mathematical model of photogrammetric point determination is based on a polynomial approach in case of airborne imagery, whereas orbital constraints should be utilized in case of spaceborne imagery. Computer simulations on point determination have turned out that the most accurate results can be obtained by simultaneous block adjustment of multiple overlapping and additional crossing strips. The usefulness of the 3-line camera concept and the applicability of the proposed mathematical models of point determination have been proven with practical airborne MEOSS and spaceborne MOMS-02 imagery. For both MEOSS and MOMS-02 imagery, empirical accuracies in object space of 1 pixel or better in planimetry and height were obtained as verified by independent check points. 1. THREE-LINE CAMERAS

In the course of the 2nd German Spacelab mission D2, scheduled for launch in 1993, the MOMS-02 ca... more In the course of the 2nd German Spacelab mission D2, scheduled for launch in 1993, the MOMS-02 camera is intended to acquire digital threefold stereo imagery of the earth's surface from space. In former simulations the influence of certain mission parameters on the attainable geometric accuracy has already been examined. With regard to the future compilation of real data, the functional model was extended with respect to the special MOMS-02 camera geometry and the actual orbit. After a brief description of the extended model, the results of new simulations are presented. They show the influence of the precision of observed exterior orientation parameters, the type and density of ground control, the camera inclination across flight direction and the simultaneous adjustment of two crossing strips with different intersection angles on the theoretical accuracy of the point determination. Because of the improved functional model the obtained accuracy estimates are expected to be repr...

We performed a photogrammetric evaluation of 36 images of Ida and its satellite, obtained by the ... more We performed a photogrammetric evaluation of 36 images of Ida and its satellite, obtained by the Galileo SSI camera during the flyby inAug. 1993 with the goal to determine the size, global shape, and, possibly, mass of the asteroid. In the first approach of our analysis we considered the rotational elements of Ida, the position of its moon, and the spacecraft trajectory to be fixed. Only camera pointingdata and image coordinates were included as estimation parameters in the adjustment procedure. We obtained (1) a dense network of ground points, (2) high-resolution terrain models in selected regions of Ida, (3) the mean position of Ida's moon at the time of the Galileo flyby. Determining the orbital motion of the small satellite is crucial, as this will offer the unique opportunity to determine the mass and density of Ida. The digital terrain models obtained in this study will be used to produce color ortho images (rectified images) for spectrophotometric analyses.