This research is focused on searching for frequency and noise characteristics for available GNSS (Global Navigation Satellite Systems). The authors illustrated frequency stability and noise ...characteristics for a selected set of data from four different GNSS systems. For this purpose, 30-s-interval clock corrections were used for the GPS weeks 1982-2034 (the entirety of 2018). Firstly, phase data (raw clock corrections) were preprocessed for shifts and removal of outliers; GLONASS and GPS satellites characterize a smaller number of outliers than BeiDou and Galileo clock products. Secondly, frequency and Hadamard deviation were calculated. This study concludes that the stability of GPS and Galileo is better than that of BDS (BeiDou Navigation Satellite System) and GLONASS. Regarding noise, the GPS, Galileo, and BDS clocks are affected by the random walk modulation noise (RWFM), flashing frequency modulation noise (FFM), and white frequency modulation noise (WFM), whereas the GLONASS clocks are mainly affected only by WFM.
Analyses of riverbed shape evolution are crucial for environmental protection and local water management. For narrow rivers located in forested, mountain areas, it is difficult to use remote sensing ...data used for large river regions. We performed a study of the Prądnik River, located in the Ojców National Park (ONP), Poland. A multitemporal analysis of various data sets was performed. Light detection and ranging (LiDAR)-based data and orthophotomaps were compared with classical survey methods, and 78 cross-sectional profiles were done via GNSS and tachymetry. In order to add an extra time step, the old maps of this region were gathered, and their content was compared with contemporary data. The analysis of remote sensing data suggests that they do not provide sufficient information on the state and changes of riverbanks, river course or river depth. LiDAR data sets do not show river bottoms, and, due to plant life, do not document riverbanks. The orthophotomaps, due to tree coverage and shades, cannot be used for tracking the whole river course. The quality of old maps allows only for general shape analysis over time. This paper shows that traditional survey methods provide sufficient accuracy for such analysis, and the resulted cross-sectional profiles can and should be used to validate other, remote sensing, data sets. We diagnosed problems with the inventory and monitoring of such objects and proposed methods to refine the data acquisition.
In this paper, I will show and describe a method of integrating infrared images with a 3D model of the front of an excavation in the longwall type of workings. I will also test the created 3D model ...for its potential usefulness in geological prospecting, used for looking for changes in geological layout at the front of the excavation. Geological information on the amount of coal in the front is important for the economic side of the excavation. The mine does not want to take out waste rock, but mostly for the safety of operations. The longwall shearers and plows are not designed for excavation in extremely changeable conditions, so if too much shale appears, this might change the speed and economic results of excavation. In addition, if a fold appears, this can destroy the excavating complex. Currently, the geological survey requires a geologist to get to the front, often to the unsupported roof part of the wall, clean the front and sample, and measure the geology. This is dangerous for the geologist. Thus, remote, infrared measurements would improve the safety of the staff and allow the survey to be taken in more places along the longwall. In this paper, I will also propose how such a system could be implemented and what the limitations are.
This study aimed to measure and validate altitudes from existing sources with direct GNSS measurements and airborne lidar data. For this purpose, 12 mountain peaks located in the south part of Polish ...territory were selected. Measurements were performed using a GNSS receiver using the Real-Time Kinematic (RTK) or static techniques enabling altitude measurements with accuracy of 10 cm. GNSS was treated as the primary data source, as the direct field measurements can determine the highest point on each peak. The obtained results were confronted with historical, internet sources, and official altitude data. Moreover, each altitude was determined using lidar data from an airborne lidar dataset of Poland from the ISOK program and provided by the national agency. Significant discrepancies in data were already detected during the analysis of internet materials and traditional maps, up to a few meters. The differences between measured and internet sources in altitude of mountain peak range from 27 cm to 504 cm. This study has shown the need to re-measure the altitudes of the mountain peaks and determine the highest point correctly.
We present an approach for extracting quantifiable information from archival aerial photographs to extend the temporal record of change over a region of the central eastern Greenland Ice Sheet. The ...photographs we use were gathered in the 1930s as part of a surveying expedition, and so they were not acquired with photogrammetric analysis in mind. Nevertheless, we are able to make opportunistic use of this imagery, as well as additional, novel datasets, to explore changes at ice margins well before the advent of conventional satellite technology. The insights that a longer record of ice margin change bring is crucial for improving our understanding of how glaciers are responding to the changing climate. In addition, our work focuses on a series of relatively small and little studied outlet glaciers from the eastern margin of the ice sheet. We show that whilst air and sea surface temperatures are important controls on the rates at which these ice masses change, there is also significant heterogeneity in their responses, with non-climatic controls (such as the role of bathymetry in front of calving margins) being extremely important. In general, there is often a tendency to focus either on changes of the Greenland Ice Sheet as a whole, or on regional variations. Here, we suggest that even this approach masks important variability, and full understanding of the behaviour and response of the ice sheet requires us to consider changes that are taking place at the scale of individual glaciers.
Knowledge of the global navigation satellite system (GNSS) satellite clock error is crucial in real-time precise point positioning (PPP), seismology, and many other high-rate GNSS applications. In ...this work, the authors show the characterisation of the atomic GNSS clock’s stability and its dependency on the adopted orbit type using Allan deviation with two methods of averaging time. Four International GNSS Service (IGS) orbit types were used: broadcast, ultra-rapid, rapid and final orbit. The calculations were made using high-rate 1 Hz observations from the IGS stations equipped with external clocks (oscillators). The most stable receiver oscillator was chosen as a reference clock. The results show the advantage of the newest GPS satellite block with respect to the other satellites. Significant differences in the results based on the orbit type used have not been recorded. Many averaging time methods used in Allan deviation (ADEV) show the clock’s fluctuations, usually smoothed in 2n s averaging times.
This paper describes the means of supporting virtual reconstruction of wooden and masonry buildings with the use of thermal infrared images. Not all remaining architectural heritage can be physically ...preserved. War, climate change and rapidly growing cities have caused damage and degradation to valuable historical buildings. In order to preserve them virtually, various methods of 3D modelling have been employed. This paper presents information on how to create a full 3D inventory of a building’s exterior. This includes a 3D thermal model of the building, merging thermal camera data with a spatial model, which aids the reconstruction of previous stages of a building’s existence. The authors argue that in cases when it is impossible to force heat transfer from inside the structure (via man‐made heating), 24 hours of observations using only solar heating can be sufficient to find heat bridges and other thermal anomalies that can be used for virtual reconstruction.
Résumé
Cet article décrit une méthode de reconstruction virtuelle de bâtiments en bois et en maçonnerie à l’aide d’images acquises en infrarouge thermique. Tout le patrimoine architectural restant ne peut pas être physiquement préservé. La guerre, le changement climatique et la croissance rapide des villes ont engendré des dommages et des dégradations sur des bâtiments historiques de grande valeur. Différentes méthodes de modélisation 3D ont été mises en œuvre pour qu’ils soient conservés virtuellement. Cet article montre comment créer l’inventaire 3D complet de l’extérieur d’un bâtiment. Cela comprend un modèle thermique 3D du bâtiment, qui fusionne les données d’une caméra thermique avec un modèle spatial, ce qui facilite la reconstruction des états antérieurs à l’existence du bâtiment. Les auteurs soutiennent que dans les cas où il est impossible de forcer le transfert de chaleur depuis l’intérieur de la structure (par chauffage artificiel), 24 heures d’observations utilisant uniquement la chaleur solaire peuvent suffire pour trouver des ponts thermiques et autres anomalies thermiques, et permettre ainsi la reconstruction virtuelle.
Zusammenfassung
Dieser Beitrag beschreibt Mittel und Wege, die virtuelle Rekonstruktion von Gebäuden aus Holz‐ und Mauerwerk mit Hilfe von thermalen Infrarot Aufnahmen zu unterstützen. Nicht alle Überreste von Baudenkmälern können physisch erhalten werden. Kriege, Klimawandel und schnell wachsende Städte haben Schäden und Zerstörung an wertvollen historischen Gebäuden verursacht. Um sie virtuell zu erhalten, wurden verschiedene Methoden der 3D Modellierung angewandt. Dieser Beitrag stellt vor, wie eine komplette 3D Inventur der Außenhülle eines Gebäudes erstellt werden kann. Dazu wird ein thermales 3D Modell des Gebäudes durch eine Verknüpfung von Thermalaufnahmen mit einem räumlichen Modell erstellt, das hilft, die vorhergehenden Phasen des Gebäudes zu rekonstruieren. Nach Meinung der Autoren, kann in dem Fall, dass eine Wärmeübertragung aus dem Inneren des Gebäudes durch künstliche Beheizung nicht möglich ist, als Alternative 24 Stunden Beobachtung unter Sonneneinstrahlung ausreichen, um Wärmebrücken und andere thermal Anomalien zu erkennen und für die virtuelle Rekonstruktion zu nutzen.
Resumen
Este artículo describe recursos para la reconstrucción virtual de edificios de madera y mampostería usando imágenes infrarrojas térmicas. No todo el patrimonio arquitectónico que ha llegado al presente puede conservarse físicamente. La guerra, el cambio climático y el rápido crecimiento de las ciudades han causado daños y degradación en edificios históricos valiosos. Para preservarlos virtualmente, se han empleado varios métodos de modelado 3D. Este documento presenta información sobre cómo crear un inventario completo 3D del exterior de un edificio. Incluyendo un modelo térmico 3D del edificio, que combina los datos de cámaras térmicas con un modelo espacial, lo que ayuda a la reconstrucción de las etapas anteriores al estado presente de un edificio. Los autores sostienen que para encontrar puentes calientes y otras anomalías térmicas que puedan usarse para la reconstrucción virtual, en aquellos casos en que forzar la transferencia de calor desde el interior de la estructura (a través de calefacción artificial) es imposible, 24 horas de observaciones utilizando solo calefacción solar pueden ser suficientes.
摘要
本文提出使用红外热影像以协助重建木制和砖石建筑虚拟模型的方法。 并非所有现存的建筑遗产均可以实体保存。 战争、气候变化和城市的快速发展，对珍贵的历史建筑造成了破坏和剥蚀。 已经有许多的三维建模方法来虚拟化保存历史建筑。 本文就创建建筑物外部完整的三维模型进行探讨。 其中包括建筑物之三维热模型，将热像仪数据与空间模型整合，有助于重建建筑物之前几个阶段的状况的。 作者认为，在无法经由建筑物内部人工加热以了解热传递的情况下，对以太阳为热源的热变化进行24小时观测，就足以找到可用于虚拟重建的热传递通道和其他热异常。
In order to preserve wooden and masonry buildings virtually, this paper presents information on creating a full 3D inventory of a building’s exterior, merging thermal camera data with a spatial model, which aids the reconstruction of previous stages of a building’s existence. Twenty‐four hours of observations using only solar heating can be sufficient to find heat bridges and other thermal anomalies that can be used for virtual reconstruction.
The Chilcayoc Chico volcano is classified as a scoria cone and a part of the Quaternary Andahua Group, southern Peru. In 2017, we performed detailed geological and morphological surveys, including a ...collection of 163 photographs that allowed for the creation of a 3D model based on Structure-from-Motion (SfM) algorithms. We compare the results of morphometric analyses of cone parameters (basal diameter, height, crater diameter) obtained in different ways: 1:50 000 scale map, satellite based DEM (from SRTM and ASTER missions), and from 3D SfM based models in order to evaluate data source quality. We concluded that maps and DEM based data is not detailed enough to bring any meaningful concussions for evaluation of age of small volcanic cones and more detailed 3D models, are necessary. We propose a method for fast image and spatial data gathering for SfM of volcanic cones. Models of Chilcayoc Chico show shelf-like structures within the crater that indicate that the cone was formed by multiple consecutive volcanic activities. We identified at least four, Strombolian or Hawaiian-type eruptive (3 Strombolian style eruption dominated episodes and 1 effusive style eruption). Evidences of effusive activity were observed, eruption dynamics became subsequently less explosive until culminating in a final effusive eruption phase. This is in contrast to previous studies that suggested that Chilcayoc Chico is a long-lived scoria cone with the sign of slight shifts of the active vents within the crater. We also provided a similar analysis of other cones from the area (Chilcayoc, Chilcayoc Grande, Jechapita, Puca Mauras) in order to estimate their relative age.
•Chilcayoc Chico Volcano Peru had 3 Strombolian and 1 Hawaiian style episodes.•1:50 000 scale maps and 30 m DEM are not sufficient for morphological analysis of small scoria cones.•SfM models are ideal for morphological analysis of small scoria cones.
The subject of this study is selection of mathematical description (interpolation method) of landslides surface for the purpose of periodic control of terrain movements. Monitoring of landslides, ...considered in this work, concerns points of periodic GPS or tacheometric measurements carried out in a relatively regular grid. For economic reasons, the grid usually consists of limited group of about several dozen of points that do not allow for an exact description of the terrain surface, nevertheless a general movement of a landslide can be detected (observed). Replacement of discrete set of points to a continuous surface model allows for a better assessment of the phenomenon especially within the scope of its main directions of activity. The choice of best performing interpolation method in order to construct a reliable numerical terrain model was performed through tests carried out on complex model surfaces. These model surfaces encompassed various configurations of terrain relief. In this study four interpolation methods i.e. splines, kriging triangulation with linear interpolation and IDW are compared. Tests on model surfaces distinguished the method of splines as the best performing one as well as the method of kriging which is suitable in some instances. The selected method of splines was then applied to periodically monitored landslide in Milówka in the south of Poland. Interpolation by means of splines allowed for observing progressive movements of the landslide surface with accuracy up to several millimeters. This confirms the usefulness and reliability of this method in landslides monitoring. Specialized field: Surveying & Geo-Spatial Engineering: Deformation Surveying.
The Valley of the Volcanoes is a representative area of the extension of the Quaternary Andahua Group with which it overlaps. Some of its eruption centres have renewed activity after more than 500 ...ka. Recreating the history of the Valley of the Volcanoes activity required satellite data and remote sensing-based methods for visualizing the terrain surface. We used SRTM 30 m DEM, channels 4, 3, 2; Landsat 7, 8 and ASTER images. We verified and refined the obtained data during field works using Structure-from-Motion (SfM) to create of 3D models of selected geoforms. Satellite data allowed us to create: Red Relief Image Map, Topographic Position Index and Normalised Difference Vegetation Index (NDVI) maps. In the Valley of the Volcanoes, we analysed 12 lava fields with a total area of 326.3 km2 and a volume of approx. 20 km3. We determined the number of eruption centres that yielded to 41 small lava domes and 23 scoria cones. This domes are classified as monogenetic volcanoes, however five of them can be considered polygenetic e.g. Puca Mauras. We used NDVI to develop chronology map of lavas. This allowed us to extract same-age eruption centres and associated volcanoes that represent the same eruptive time phase connected by fault lines: first generation (0.5–0.27 Ma) NW-SE and NE-SW, second (Pleistocene/Holocene) NNW-SSE and third (Holocene-Historical) again NW-SE and NE-SW. We carried out the reconstruction of the central part of the Valley of the Volcanoes because only there repeated phases of volcanic activity can be inferred with remote sensing and geological mapping. The results of this study led us to indicate that this area should be observed since it is very likely that future eruptions will occur.
Display omitted
PDF
