Dr. Hartmut M. Schimpf Profile

Dr. Hartmut M. Schimpf

at Fraunhofer FHR

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Publications (9)

Proceedings Article | 19 May 2011 Paper

Variability and robustness of scatterers in HRR/ISAR ground target data and its influence on the ATR performance

R. Schumacher, H. Schimpf, J. Schiller

Proceedings Volume 8049, 804911 (2011) https://doi.org/10.1117/12.882289

KEYWORDS: Automatic target recognition, Radar, Scattering, Synthetic aperture radar, Matrices, Image resolution, Image processing, Target recognition, Feature extraction, Statistical analysis

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The most challenging problem of Automatic Target Recognition (ATR) is the extraction of robust and independent target features which describe the target unambiguously. These features have to be robust and invariant in different senses: in time, between aspect views (azimuth and elevation angle), between target motion (translation and rotation) and between different target variants. Especially for ground moving targets in military applications an irregular target motion is typical, so that a strong variation of the backscattered radar signal with azimuth and elevation angle makes the extraction of stable and robust features most difficult. For ATR based on High Range Resolution (HRR) profiles and / or Inverse Synthetic Aperture Radar (ISAR) images it is crucial that the reference dataset consists of stable and robust features, which, among others, will depend on the target aspect and depression angle amongst others. Here it is important to find an adequate data grid for an efficient data coverage in the reference dataset for ATR. In this paper the variability of the backscattered radar signals of target scattering centers is analyzed for different HRR profiles and ISAR images from measured turntable datasets of ground targets under controlled conditions. Especially the dependency of the features on the elevation angle is analyzed regarding to the ATR of large strip SAR data with a large range of depression angles by using available (I)SAR datasets as reference. In this work the robustness of these scattering centers is analyzed by extracting their amplitude, phase and position. Therefore turntable measurements under controlled conditions were performed targeting an artificial military reference object called STANDCAM. Measures referring to variability, similarity, robustness and separability regarding the scattering centers are defined. The dependency of the scattering behaviour with respect to azimuth and elevation variations is analyzed. Additionally generic types of features (geometrical, statistical), which can be derived especially from (I)SAR images, are applied to the ATR-task. Therefore subsequently the dependence of individual feature values as well as the feature statistics on aspect (i.e. azimuth and elevation) are presented. The Kolmogorov-Smirnov distance will be used to show how the feature statistics is influenced by varying elevation angles. Finally, confusion matrices are computed between the STANDCAM target at all eleven elevation angles. This helps to assess the robustness of ATR performance under the influence of aspect angle deviations between training set and test set.

Proceedings Article | 19 May 2011 Paper

The influence of multipath on ship ATR performance

Hartmut Schimpf

Proceedings Volume 8049, 804912 (2011) https://doi.org/10.1117/12.880747

KEYWORDS: Matrices, Radar, Antennas, Automatic target recognition, Sensors, Atmospheric modeling, Atmospheric propagation, Reflection, Reflectivity, Statistical analysis

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Proceedings Article | 22 October 2010 Paper

Polarimetric millimetre wave SAR for precision farming applications

H. Essen, D. Nüßler, C. Krebs, H. Schimpf, W. Johannes, A. Wahlen

Proceedings Volume 7824, 78241Q (2010) https://doi.org/10.1117/12.863519

KEYWORDS: Synthetic aperture radar, Radar, Reflectivity, Polarimetry, Polarization, Vegetation, Humidity, Sensors, Data modeling, Extremely high frequency

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Proceedings Article | 5 May 2009 Paper

Polarimetric calibration and its influence on target recognition performance

Hartmut Schimpf

Proceedings Volume 7335, 73350Z (2009) https://doi.org/10.1117/12.818107

KEYWORDS: Polarimetry, Calibration, Automatic target recognition, Scattering, Matrices, Radar, Polarization, Target recognition, Reflectivity, Sensors

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Proceedings Article | 21 September 2004 Paper

Millimeter-wave ATR: a study on feature robustness

Hartmut Schimpf

Proceedings Volume 5426, (2004) https://doi.org/10.1117/12.542057

KEYWORDS: Polarimetry, Automatic target recognition, Statistical analysis, Target recognition, Distance measurement, Radar, Principal component analysis, Synthetic aperture radar, Extremely high frequency, Pattern recognition

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Proceedings Article | 5 February 2004 Paper

Polarimetric properties of land clutter at millimeterwave bands

Helmut Essen, Hartmut Schimpf

Proceedings Volume 5238, (2004) https://doi.org/10.1117/12.510668

KEYWORDS: Polarimetry, Polarization, Reflectivity, Synthetic aperture radar, Calibration, Stereolithography, Automatic target recognition, Algorithm development, Doppler effect, Data modeling

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Proceedings Article | 19 July 2000 Paper

Aspects of automatic target recognition with a two-frequency millimeter-wave SAR

Elmar Seidenberg, Hartmuf Schimpf

Proceedings Volume 4033, (2000) https://doi.org/10.1117/12.391847

KEYWORDS: Synthetic aperture radar, Polarimetry, Doppler effect, Polarization, Scattering, Target detection, Automatic target recognition, Antennas, Fourier transforms, Cesium

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Proceedings Article | 7 July 1998 Paper

Millimeter-wave interferometric SAR and polarimetry

Stephan Boehmsdorff, Helmut Essen, Hartmuf Schimpf, Alfred Wahlen

Proceedings Volume 3375, (1998) https://doi.org/10.1117/12.327173

KEYWORDS: Polarimetry, Interferometry, Radar, Synthetic aperture radar, Polarization, Interferometric synthetic aperture radar, Scattering, Image processing, Antennas, Sensors

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Using synthetic aperture radars with appropriate signal processing algorithms is a recognized technique for remote sensing applications. A wide spectrum of radar frequencies is used and a high degree of sophistication implies polarimetric and further multichannel approaches. Each frequency band used, exhibits special sensitivities to features of the earth's surface or man-made targets. This is mostly due to the coupling of the electromagnetic waves to backscattering geometries which are related to the radarwavelength. A part of the spectrum which has been covered not very intensely is the millimeterwave region. This may be mostly due to the relatively high atmospheric absorption at millimeterwaves which obstructs the use of such sensors for long range applications. On the other hand for military applications IR-imaging sensors are widely used which suffer even more from adverse transmission properties of the atmosphere. Application of multichannel techniques as polarimetry, multifrequency techniques and interferometry are also done with more ease due to compactness of the hardware and simplicity of processing. As there exist no data which would allow to investigate the potential of multifrequency polarimetric and interferometric mmW-SAR the Millimeterwave Experimental Multifrequency Polarimetric High Resolution Interferometric Imaging System was installed into an aircraft C-160 `Transall' to gather respective data over different land scenarios. The off-line evaluation of the radar data starts with off-line track, calibration and reformatting procedures. Afterwards synthetic aperture processing is applied to these data to generate radar images for co- and cross-polarization at 35 GHz and 94 GHz. As already mentioned above, SAR-processing at millimeterwavelengths requires a considerable lower amount of sophistication in comparison with algorithms applied at lower radar-frequencies. This can mainly be attributed to the short aperture length at mm-wave frequencies. Taking this into account, the SAR-algorithm used here is relatively simple although fully automatic autofocussing is applied, using only radar-data without supply of external INS information. The interferometric evaluation uses phase unwrapping techniques tailored to the high resolution achieved at mm-waves. The paper describes experiments with the interferometric 35/94-GHz-SAR, describes the IFSAR and phase unwrapping algorithms as well as polarimetric segmentation approaches and shows respective results.

Proceedings Article | 22 July 1997 Paper

SAR measurements of mines and minefields at 35 GHz and 94 GHz

Hartmuf Schimpf, M. Puehl, Gregor Biegel

Proceedings Volume 3079, (1997) https://doi.org/10.1117/12.280890

KEYWORDS: Land mines, Mining, Synthetic aperture radar, Extremely high frequency, Polarization, Radar, Doppler effect, Sensors, Lawrencium, Image processing

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Showing 5 of 9 publications

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