Integrated recovery of elevation and photometric reflectance properties from hyperspectral data

The analysis of optical measurements, i.e. images, may be subdivided into methods with respect to the spatial reflectance distribution, e.g. bundle adjustment and shape from shading, and methods with respect to the spectral reflectance distribution, e.g. determination of object properties based on its colour. Current research considers these problems separately. Hyperspectral imagery, however, simultaneously provides knowledge on the local surface topography, i.e. shading, and the spectral reflectance. One problem that requires treatment in all methods is the dependence of the object's appearance on its shape. The goal of this thesis is to bridge the gap between spatial and spectral analysis of reflectance data, i.e. to extract and combine the spatial and the spectral information from hyperspectral images. This is achieved by an integrated framework for the recovery of local surface topography and the normalisation of spectral data. Photometric shape recovery methods derive the surface orientation, i.e. its gradient field, from the image and retrieve the shape by integrating the estimated gradient field, which is prone to the accumulation of systematic errors originating from the gradient estimation. To suppress these systematic errors, the photometric shape recovery is re-stricted by soft constraints derived from topographic models of lower lateral resolution. These soft constraints are applied to both the gradient field estimation and the gradient field integration. The earth's moon has been of scientific interest for a long time and thus a wealth of measurements exists and is publicly available. The available measurements include high resolution topography models derived from stereo image analysis and laser altimeter measurements, hyperspectral reflec-tance measurements and elemental abundances measured by gamma ray spectrometers. This wealth of data is rarely met in industrial applications and thus the lunar surface is an ideal object for the method development. The developed methods include the refinement, i.e. increase of lateral resolution, of stereo based topographic model and the estimation of the surface's temperature and the parameters of the reflectance model. The computed values allow for a normalisation of the spec-tral data and compensation of the thermal component. The developed techniques are applied to derive a near-global Moon Mineralogy Mapper mosaic. Based on this mosaic, a regression method is applied to map parameters of the spectral absorption bands onto elemental abundances measured by the Lunar Prospector Gamma-Ray Spectrometer. To obtain co-registered images, which are required for an analysis of the spectral data, an illumination independent image registration method is developed based on the recovered elevation models, which, by definition, are co-registered to the original image. Finally, the photometric surface refine-ment methods are applied to Lunar Orbiter Narrow Angle Camera images to derive to elevation models of the highest possible resolution. The results show that the influence of the local topography is nearly eliminated from the normalised reflectance maps. A qualitative analysis of the obtained parameters of the reflectance model, e.g. the single-scattering albedo, is in good agreement with known bright and dark areas, e.g. bright volcanic domes or ash deposits. An analysis of the temperature estimation shows, that accurate estimates of temperatures above 300 K are possible. Comparing the results of the refined topographic models to single high accuracy laser altimeter measurements show that the depth error is comparable to stereo analysis while the lateral resolution is greatly increased. The presented image registration technique based on the topography models achieves sub-pixel accuracy.Die Analyse von optischen Messungen, d. h. Bildern, kann in zwei Gruppen von Methoden eingeteilt werden: Die Analyse der räumlichen Reflektanzverteilung, z. B. Bündelausgleich, und die Analyse der spektralen Reflektanz, z. B. die Bestimmung von Objekteigenschaften auf Basis der Objektfarbe. Übli-cherweise werden beide Methoden getrennt entwickelt. Allerdings ist allen Methoden die Grund-problematik der Abhängigkeit der gemessenen Reflektanz von der Objektform gemein. Ziel dieser Arbeit ist es beide Gruppen zu vereinen und die für die Normalisierung der spektralen Reflektanz geschätzten Reflektanzfunktion für die photometrische Bestimmung der Objektform, z. B. mittels Shape-from-Shading, zu nutzen. Photometrische Methoden nutzen die Abhängigkeit der Objekt-reflektanz von seiner Form um die Orientierung, d. h. das Gradientenfeld, der Objektoberfläche zu bestimmen. In einem zweiten Schritt wird die Form durch Integration des Gradientenfeldes ermittelt. Daher sind photometrische Methoden anfällig für die Akkumulation kleiner, systematischer Fehler bei der Bestimmung des Gradientenfeldes. Um diese Effekte zu beseitigen wird die photometrische Bestimmung der Oberfläche durch Oberflächendaten mit geringerer lateraler Auflösung einge-schränkt. Dies geschieht durch das Einführen sogenannter Soft-Constraints in beiden Stufen der pho-tometrischen Rekonstruktion. Der Mond ist schon lange Forschungsgegenstand und so ist ein gewaltiger Fundus an Daten der Öf-fentlichkeit zugänglich. Diese Messdaten sind z. B. Topographiemodelle aus Stereobildanalyse und Laser Altimetrie, Hyperspektraldaten sowie mittels Gammastrahlenspektroskopie ermittelte Ele-menthäufigkeiten. Daher bildet der Mond ein ideales Testobjekt für die Entwicklung von Methoden. Diese beinhalten die Erhöhung der lateralen Auflösung von topographischen Modellen durch photo-metrische Methoden sowie die Ermittlung der Oberflächentemperatur und der Reflektanzmodell-parameter. Die ermittelten Größen ermöglichen eine Normalisierung der spektralen Reflektanz und eine Kompensation der von der Oberfläche abgestrahlten thermischen Komponente. Die Entwickelten Methoden werden genutzt um ein nahezu globales Moon Mineralogy Mapper Mo-saik zu normalisieren. Ausgehend von dem normalisierten Mosaik wird eine Regressionsmethode genutzt um die spektralen Absorptionen, welche durch bestimmte Elemente in den Mineralen er-zeugt werden, auf die Elementhäufigkeitskarten des Lunar Prospector Gamma-Ray Spectrometers abzubilden. Weil für die Analyse pixelsynchrone Bilder erforderlich sind wird eine robuste und be-leuchtungsunabhängige Bildregistrierungsmethode aus den entwickelten Methoden abgeleitet. Au-ßerdem werden die entwickelten photometrischen Methoden genutzt um aus Lunar Orbiter Narrow Angle Camera Bildern topographische Modelle mit der höchstmöglichen Auflösung zu erzeugen. Die Ergebnisse zeigen, dass der Einfluss der lokalen Topographie auf die Spektraldaten nahezu besei-tigt wird. Eine qualitative Analyse der ermittelten Reflektanzmodellparameter zeigt gute Überein-stimmung mit den bekannten geologischen Verteilungen von hellen und dunklen Gebieten, z. B. helle Vulkankuppen und dunkle Ascheablagerungen. Eine Analyse der Oberflächentemperaturschätzung zeigt, dass Temperaturen über 300 K geschätzt werden können. Ein Vergleich der erzeugten topogra-phischen Modelle mit hochgenauen Laser-Messungen zeigt, dass die vertikale Genauigkeit erhalten bleibt, während der visuelle Eindruck eindeutig eine Verbesserung der lateralen Auflösung gegen-über der Stereobasierten Modelle zeigt. Die abgeleitete Bildregistrierungsroutine auf Basis der topo-graphischen Modelle erreicht Genauigkeiten von unter einem Pixel

Can a Red Wood-Ant Nest Be Associated with Fault-Related CH4 Micro-Seepage? A Case Study from Continuous Short-Term In-Situ Sampling

Simple Summary Methane (CH4) is common on Earth but its natural sources are not well-characterized. We investigated concentrations of CH4 and its stable carbon isotope (δ13C-CH4) within a red wood-ant (RWA; Formica polyctena) nest in the Neuwied Basin, a part of the East Eifel Volcanic Field (EEVF), and tested for associations between methane concentration and RWA activity patterns, earthquakes, and earth tides. Methane degassing was not synchronized with earth tides, nor was it influenced by a micro-earthquake or RWA activity. Elevated CH4 concentrations in nest gas appear to result from a combination of microbial activity and fault-related emissions. The latter could result from micro-seepage of methane derived from low-temperature gas-water-rock reactions that subsequently moves via fault networks through the RWA nest or from overlapping micro-seepage of magmatic CH4 from the Eifel plume. Given the abundance of RWA nests on the landscape, their role as sources of microbial CH4 and biological indicators for abiotically-derived CH4 should be included in estimations of methane emissions that are contributing to climatic change. Abstract We measured methane (CH4) and stable carbon isotope of methane (δ13C-CH4) concentrations in ambient air and within a red wood-ant (RWA; Formica polyctena) nest in the Neuwied Basin (Germany) using high-resolution in-situ sampling to detect microbial, thermogenic, and abiotic fault-related micro-seepage of CH4. Methane degassing from RWA nests was not synchronized with earth tides, nor was it influenced by micro-earthquake degassing or concomitantly measured RWA activity. Two δ13C-CH4 signatures were identified in nest gas: −69‰ and −37‰. The lower peak was attributed to microbial decomposition of organic matter within the RWA nest, in line with previous observations that RWA nests are hot-spots of microbial CH4. The higher peak has not been reported in previous studies. We attribute this peak to fault-related CH4 emissions moving via fault networks into the RWA nest, which could originate either from thermogenic or abiotic CH4 formation. Sources of these micro-seepages could be Devonian schists, iron-bearing “Klerf Schichten”, or overlapping micro-seepage of magmatic CH4 from the Eifel plume. Given the abundance of RWA nests on the landscape, their role as sources of microbial CH4 and biological indicators for abiotically-derived CH4 should be included in estimation of methane emissions that are contributing to climatic change

Single view single light multispectral object segmentation

In this paper we present an approach for the acquisition and segmentation of spectral Bidirectional Reflectance Distribution Function (BRDF) measurements of real-world objects. The acquisition setup is a priori fully calibrated and provides pixel-synchronous image and depth data of the examined objects. Based on one single viewing and illumination geometry, we are able to determine spectrally distinct surface regions for objects with abruptly changing surface materials (painted surface patches) and for objects with gradually changing materials (partially oxidized iron). For clustering we apply the k-means algorithm and the mean-shift algorithm. The segmented clusters are used to adapt individual spectral BRDFs (Lambert, Phong, Cook-Torrance) to the obtained cluster data. Additionally, the elemental abundances of iron and rust on a metal surface are analyzed using spectral unmixing. The paper presents a detailed discussion of our method and provides critical insight into the obtained results

Early Results of Three-Year Monitoring of Red Wood Ants’ Behavioral Changes and Their Possible Correlation with Earthquake Events

Short-term earthquake predictions with an advance warning of several hours or days are currently not possible due to both incomplete understanding of the complex tectonic processes and inadequate observations. Abnormal animal behaviors before earthquakes have been reported previously, but create problems in monitoring and reliability. The situation is different with red wood ants (RWA; Formica rufa-group (Hymenoptera: Formicidae)). They have stationary mounds on tectonically active, gas-bearing fault systems. These faults may be potential earthquake areas. For three years (2009–2012), two red wood ant mounds (Formica rufa-group), located at the seismically active Neuwied Basin (Eifel, Germany), have been monitored 24/7 by high-resolution cameras with both a color and an infrared sensor. Early results show that ants have a well-identifiable standard daily routine. Correlation with local seismic events suggests changes in the ants’ behavior hours before the earthquake: the nocturnal rest phase and daily activity are suppressed, and standard daily routine does not resume until the next day. At present, an automated image evaluation routine is being applied to the more than 45,000 hours of video streams. Based on this automated approach, a statistical analysis of the ants’ behavior will be carried out. In addition, other parameters (climate, geotectonic and biological), which may influence behavior, will be included in the analysis

Global mapping of lunar refractrory elements: multivariate regression vs. machine learning

天体を構成する元素はそれぞれ特徴的な波長吸収を示す。本研究ではChandrayaan-1に搭載されたMoon Mineralogy Mapper (M3)によって計測された月面の鉱物分布とLunar Prospectorおよびかぐや（SELENE）搭載のガンマ線分光計の元素分布を用いて各鉱物の主要な構成元素の詳細な月面分布を取得した

Can a red wood-ant nest be associated with fault-related CH4 micro-seepage?

We measured methane (CH4) and stable carbon isotope of methane (δ13C-CH4) concentrations in ambient air and within a red wood-ant (RWA; Formica polyctena) nest in the Neuwied Basin (Germany) using high-resolution in-situ sampling to detect microbial, thermogenic, and abiotic fault-related micro-seepage of CH4. Methane degassing from RWA nests was not synchronized with earth tides, nor was it influenced by micro-earthquake degassing or concomitantly measured RWA activity. Two δ13C-CH4 signatures were identified in nest gas: −69‰ and −37‰. The lower peak was attributed to microbial decomposition of organic matter within the RWA nest, in line with previous observations that RWA nests are hot-spots of microbial CH4. The higher peak has not been reported in previous studies. We attribute this peak to fault-related CH4 emissions moving via fault networks into the RWA nest, which could originate either from thermogenic or abiotic CH4 formation. Sources of these micro-seepages could be Devonian schists, iron-bearing “Klerf Schichten”, or overlapping micro-seepage of magmatic CH4 from the Eifel plume. Given the abundance of RWA nests on the landscape, their role as sources of microbial CH4 and biological indicators for abiotically-derived CH4 should be included in estimation of methane emissions that are contributing to climatic change