Toward reduction of artifacts in fused images

Most fusion satellite image methodologies at pixel-level introduce false spatial details, i.e.artifacts, in the resulting fusedimages. In many cases, these artifacts appears because image fusion methods do not consider the differences in roughness or textural characteristics between different land covers. They only consider the digital values associated with single pixels. This effect increases as the spatial resolution image increases. To minimize this problem, we propose a new paradigm based on local measurements of the fractal dimension (FD). Fractal dimension maps (FDMs) are generated for each of the source images (panchromatic and each band of the multi-spectral images) with the box-counting algorithm and by applying a windowing process. The average of source image FDMs, previously indexed between 0 and 1, has been used for discrimination of different land covers present in satellite images. This paradigm has been applied through the fusion methodology based on the discrete wavelet transform (DWT), using the à trous algorithm (WAT). Two different scenes registered by optical sensors on board FORMOSAT-2 and IKONOS satellites were used to study the behaviour of the proposed methodology. The implementation of this approach, using the WAT method, allows adapting the fusion process to the roughness and shape of the regions present in the image to be fused. This improves the quality of the fusedimages and their classification results when compared with the original WAT metho

Soil moisture estimation from Sentinel-1 interferometric observations over arid regions

We present a methodology based on interferometric synthetic aperture radar (InSAR) time series analysis that can provide surface (top 5 cm) soil moisture (SSM) estimations. The InSAR time series analysis consists of five processing steps. A co-registered Single Look Complex (SLC) SAR stack as well as meteorological information are required as input of the proposed workflow. In the first step, ice/snow-free and zero-precipitation SAR images are identified using meteorological data. In the second step, construction and phase extraction of distributed scatterers (DSs) (over bare land) is performed. In the third step, for each DS the ordering of surface soil moisture (SSM) levels of SAR acquisitions based on interferometric coherence is calculated. In the fourth step, for each DS the coherence due to SSM variations is calculated. In the fifth step, SSM is estimated by a constrained inversion of an analytical interferometric model using coherence and phase closure information. The implementation of the proposed approach is provided as an open-source software toolbox (INSAR4SM) available at www.github.com/kleok/INSAR4SM. A case study over an arid region in California/Arizona is presented. The proposed workflow was applied in Sentinel- 1 (C-band) VV-polarized InSAR observations. The estimated SSM results were assessed with independent SSM observations from a station of the International Soil Moisture Network (ISMN) (RMSE: 0.027 $m^3/m^3$ R: 0.88) and ERA5-Land reanalysis model data (RMSE: 0.035 $m^3/m^3$ R: 0.71). The proposed methodology was able to provide accurate SSM estimations at high spatial resolution (~250 m). A discussion of the benefits and the limitations of the proposed methodology highlighted the potential of interferometric observables for SSM estimation over arid regions

Landslide detection using ALOS optical and radar data. A case study from the Ilia prefecture.

Στην εργασία αυτή παρουσιάζεται  η χρήση οπτικών δεδομένων καθώς και ραντάρ δεδομένων  από  το  δορυφόρο ALOS   για  τον  εντοπισμό  μίας  κατολίσθησης.  Ο δορυφόρος ALOS   διαθέτει  τρεις  δέκτες.  Έναν  παγχρωματικό  δέκτη  (PRISM)  που λαμβάνει στερεοεικόνες, ένα   πολυφασματικό δέκτη (AVNIR-2) και ένα δέκτη ραντάρ (PALSAR).   Η περιοχή μελέτης εντοπίζεται στη Δυτική Πελοπόννησο στην περιοχή της Ανδρίτσαινας και  συγκεκριμένα  στο  χωριό  Συκιές.  Η  περιοχή  υπέστη  σημαντικές καταστροφές  από  τις  πυρκαγιές  του  2007.  Σαν  αποτέλεσμα πολλές  κατολισθήσεις καταγράφησαν  τα επόμενα  χρόνια. Η  συγκεκριμένη κατολίσθηση  σημειώθηκε  τον Ιανουάριο του 2009 συνεπεία πολύ έντονων βροχοπτώσεων και χαρτογραφήθηκε στο πεδίο  με  χρήση DGPS   .  Η  δυνατότητα  εντοπισμού  της  κατολίσθησης  από  τα δορυφορικά δεδομένα ALOS  εξετάζεται στην παρούσα εργασία και παρουσιάζονται τα αποτελέσματα. Γίνεται χρήση τεχνικών συμβολομετρίας για την επεξεργασία τριάντα εικόνων ραντάρ καθώς και χρήση φωτογραμμετρικών τεχνικών για την επεξεργασία των στερεοσκοπικών οπτικών δεδομένων.In this study the usefulness of the ALOS optical and radar data for landslide monitoring  is  examined.  ALOS  contains  three  sensors,  commonly  referred  to  as  the “three eyes” of ALOS. These sensors are: the Panchromatic Remote-Sensing Instrument for Stereo Mapping (PRISM), the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2), and the Phased Array type L-band Synthetic Aperture Radar (PALSAR). The area of study is located in a small village named Sykies near to the city of Andritsena in Western Peloponnese. The area suffered during the last years from enormous fires. As a result many landslides have been recorded. One of the latest Landslides has been recorded on January 2009 as a consequence of heavy rains. That landslide was mapped in situ using differential GPS. The possibility of detecting and mapping the specific landslide using ALOS data is examined in this study and the results are presented. Thirty ALOS radar images within a period of three years, two ALOS Prism data sets and two ALOS AVNIR collected over the same area within a year were used

Landslide detection using ALOS optical and radar data. A case study from the Ilia prefecture.

Στην εργασία αυτή παρουσιάζεται  η χρήση οπτικών δεδομένων καθώς και ραντάρ δεδομένων  από  το  δορυφόρο ALOS   για  τον  εντοπισμό  μίας  κατολίσθησης.  Ο δορυφόρος ALOS   διαθέτει  τρεις  δέκτες.  Έναν  παγχρωματικό  δέκτη  (PRISM)  που λαμβάνει στερεοεικόνες, ένα   πολυφασματικό δέκτη (AVNIR-2) και ένα δέκτη ραντάρ (PALSAR).   Η περιοχή μελέτης εντοπίζεται στη Δυτική Πελοπόννησο στην περιοχή της Ανδρίτσαινας και  συγκεκριμένα  στο  χωριό  Συκιές.  Η  περιοχή  υπέστη  σημαντικές καταστροφές  από  τις  πυρκαγιές  του  2007.  Σαν  αποτέλεσμα πολλές  κατολισθήσεις καταγράφησαν  τα επόμενα  χρόνια. Η  συγκεκριμένη κατολίσθηση  σημειώθηκε  τον Ιανουάριο του 2009 συνεπεία πολύ έντονων βροχοπτώσεων και χαρτογραφήθηκε στο πεδίο  με  χρήση DGPS   .  Η  δυνατότητα  εντοπισμού  της  κατολίσθησης  από  τα δορυφορικά δεδομένα ALOS  εξετάζεται στην παρούσα εργασία και παρουσιάζονται τα αποτελέσματα. Γίνεται χρήση τεχνικών συμβολομετρίας για την επεξεργασία τριάντα εικόνων ραντάρ καθώς και χρήση φωτογραμμετρικών τεχνικών για την επεξεργασία των στερεοσκοπικών οπτικών δεδομένων.In this study the usefulness of the ALOS optical and radar data for landslide monitoring  is  examined.  ALOS  contains  three  sensors,  commonly  referred  to  as  the “three eyes” of ALOS. These sensors are: the Panchromatic Remote-Sensing Instrument for Stereo Mapping (PRISM), the Advanced Visible and Near Infrared Radiometer type 2 (AVNIR-2), and the Phased Array type L-band Synthetic Aperture Radar (PALSAR). The area of study is located in a small village named Sykies near to the city of Andritsena in Western Peloponnese. The area suffered during the last years from enormous fires. As a result many landslides have been recorded. One of the latest Landslides has been recorded on January 2009 as a consequence of heavy rains. That landslide was mapped in situ using differential GPS. The possibility of detecting and mapping the specific landslide using ALOS data is examined in this study and the results are presented. Thirty ALOS radar images within a period of three years, two ALOS Prism data sets and two ALOS AVNIR collected over the same area within a year were used

Charakterisierung von Tumorstammzellen des Medulloblastoms und Analyse ihrer molekularen Regulation

Das maligne Medulloblastom, welches aus unreifen neuralen Zellen des Kleinhirnes entsteht, zeigt eine zelluläre und molekulare Heterogenität. Die CSC (Cancer Stem Cell)-Hypothese soll zu einem besseren Verständnis der Tumorbiologie mithilfe eines hierarchisch aufgebauten Modells verhelfen. Wesentliche Aspekte dieser Hypothese sind die Selbsterneuerungs- und Differenzierungs-Fähigkeit von Tumorstammzellen. Dabei stehen die sich selbsterneuernden Tumorstammzellen unter der Kontrolle von Signalwegen, die dereguliert/aktiviert sein und zur unkontrollierten Proliferation führen können. Im Medulloblastom wurden CD133 positive Zellen mit Stammzelleigenschaften identifiziert. In der vorliegenden Arbeit wurden die Charakterisierung von Tumorstammzellen des Medulloblastoms und die Analyse ihrer molekularen Regulation zunächst mithilfe des CD133-Tumorstammzellmarkers analysiert. Hierbei wurde festgestellt, dass CD133-positive Subpopulationen der D283 Med Linie eine höhere Kapazität zur Neurosphärenbildung hatte als CD133-negative. Jedoch korrelierte die Potenz, Neurosphären auszubilden, nicht in allen Zellmodellen mit der Expression des Tumorstammzellmarkers CD133. Die verschiedenen untersuchten Medulloblastomzellen wiesen in vitro ein unterschiedliches ausgeprägtes Selbsterneuerungs-Potential auf. Des Weiteren wurden in CD133-angereicherten Zellpopulationen differentiell exprimierte Gene mittels Array-Hybridisierung identifiziert und mittels quantitativer PCR (Taqman) validiert. In der CD133-angereicherten Population konnten wir das im pränatalen Gehirn exprimierte Gen MPPED2, sowie TTR (Transthyretin) als überexprimiert identifizieren. Zellzyklus-Analysen ergaben, dass sich CD133-positive Populationen eher im Zellzyklus befinden und CD133-negative in der G0/G1-Phase. Im DAOY-Zellmodell konnten wir keine langsam proliferierenden Stammzellen mit der Methode des Label Retaining nachweisen. Die in Stammzellen und Vorläuferzellen erhöhte Aldehyddehydrogenase-Aktivität wurde als weiteres Charakteristikum untersucht. Hierbei fanden sich überlappende CD133+- und ALDH+-Populationen, mit Nachweis einer doppelt positiven Fraktion. Die Entwickungskontrollsignalwege Sonic Hedgehog, Notch und Wnt regulieren das Zellschicksal von normalen Stammzellen und von Tumorstammzellen. Die Untersuchung der Abhängigkeit der Zellen von diesen drei Entwicklungskontrollsignalwegen mittels spezifischer Inhibierung oder Stimulierung führte zu einer heterogenen Antwort in Hinsicht auf die Bildung von Neurosphären. Dieses Ergebnis weist erneut auf die Diversität des aus unterschiedlichen Zelltypen entstehenden Medulloblastoms auf. Die Differenzierungs-Fähigkeit von Neurosphären fand sich eingeschränkt; es konnten auch unter differenzierenden Bedingungen Stammzell- bzw. Vorläufermarker wie Sox2 nachgewiesen werden; eine terminale Differenzierung der Medulloblastomzellen blieb aus. Die Charakterisierung von Medulloblastom-Stammzellen und ihre Bedeutung für die Klinik der Patienten bedarf weiterer AnalysenCharacterization of medulloblastoma stem cells and analysis of their molecular regulation The malignant medulloblastoma, which arises from immature neural cells of the cerebellum, shows cellular and molecular heterogeneity. The CSC (cancer stem cell) hypothesis should provide a better understanding of the tumour biology using a hierarchical model. Key aspects of this hypothesis are the self-renewal and differentiation ability of cancer stem cells. The self-renewing cancer stem cells are under the control of developmental signaling pathways that can be deregulated / activated and may lead to uncontrolled proliferation. CD133 positive cells with stem cell properties were identified in the medulloblastoma. In the present work, the characterization of tumour stem cells of the medulloblastoma and the analysis of their molecular regulation were initially analysed using the CD133 cancer stem cell marker. Here it was found that CD133 positive subpopulations of the D283 Med cell line possessed a higher capacity for neurosphere formation than CD133 negative cells. However, the capacity for neurosphere formation did not correlate with the expression of the tumour stem cell marker CD133 in all cell models. The various medulloblastoma cells that were studied showed a distinct self-renewal potential in vitro. Furthermore, CD133-enriched cell populations revealed differentially expressed genes by way of microarray hybridisation. These genes were validated by way of quantitative PCR (Taqman). We were able to identify MPPED2 and TTR (Transthyretin) genes that were over-expressed in the CD133-enriched population. MPPED2 is expressed in the prenatal brain. Cell cycle analysis revealed that CD133 positive populations are predominantly active in cycling cells, while CD133 negative populations are found in the G0/G1 phase. It was not possible to detect slow-cycling stem cells in the DAOY cell model using the label retaining cell approach.The increased aldehyde dehydrogenase activity in stem cells and progenitor cells was investigated as a further characteristic. Here there were overlapping CD133+ and ALDH+ populations, with evidence of a double-positive fraction. The developmental control signaling pathways Sonic hedgehog, Notch and Wnt regulate the cell fate of normal stem cells and tumour stem cells. The study of the cells as a function of these three developmental control signaling pathways by means of specific inhibition or stimulation resulted in a heterogeneous response with respect to the formation of neurospheres. This result again demonstrates the diversity of the medulloblastoma consisting of different cell types. The differentiation ability of neurospheres was restricted. It was also possible to detect stem cell markers and progenitor markers, such as Sox2, under differentiating conditions. Terminal differentiation of medulloblastoma cells was not possible. Characterizing medulloblastoma stem cells and their significance for the patient’s clinic requires further analysis

Estimation of the Number of Endmembers Using Robust Outlier Detection Method

This paper introduces a novel approach for estimating the numbers of endmembers in hyperspectral imagery. It exploits the geometrical properties of the noise hypersphere and considers the signal as outlier of the noise hypersphere. The proposed method, called outlier detection method (ODM), is automatic and non-parametric. In a principal component space, noise is spherically symmetric in all directions and lies on the surface of a hypersphere with a constant radius. Reversely, signal radiuses are much larger that noise radius and vary in all directions, thus signal lies in a hyperellipsoid. The proposed method involves three steps: 1) noise estimation; 2) minimum noise fraction transformation; and 3) outlier detection using inter quartile range. Estimation of the number of endmembers is accomplished by the estimation of the number of noise hypersphere outliers using a robust outlier detection method. The ODM was evaluated using simulated and real hyperspectral data, and it was also compared with well-known methods for estimating the number of endmembers. Evaluation of the method showed that the method produces robust and satisfactory results, and outperforms in relation to its competitors

Exploring elements of the cheese purchase decision process through application of purchasing involvement methodology : the case of cheese products in Athens, Greece.

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Exploring elements of the cheese purchase decision process through application of purchasing involvement methodology The case of cheese products in Athens, Greece

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