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Permafrost is extremely sensitive to variance in external hydrothermal conditions. InSAR has advantages in monitoring surface deformation with decent temporal and spatial resolution as well as mill...

Marine Geodesy will publish a special issue on Seafloor Geodesy and Acoustic Positioning in early 2022. The guest editors will be Prof. Yuanxi Yang from Xi'an Research Institute of Surveying and Ma...

Marine Geodesy will publish a special issue on Cryosphere and Climate Change in late 2019. The guest editors will be Dr. Yinsheng Zhang from Chinese Academy of Science and Dr Tong Hao from Tongji U...

This paper introduces a new method for bluffline extraction based on analysis of surface normal vectors derived from a 2.5-dimensional Delaunay triangulation network generated using a set of LiDAR points. The developed method has been implemented and tested for the extraction of blufflines in a section of the Lake Erie coastline near Painesville, Ohio. Comparison of the research results with those generated by a method for bluffline extraction based on slope information along elevation profiles on transects shows an improvement in both horizontal and vertical accuracies in situations where the bluff has a relatively sharp edge formation.

Changes in the coverage of seagrass populations are considered to be a key indicator of the health and biodiversity of coastal ecosystems. The overall extent of seagrass meadows is declining worldwide, primarily due to human-induced disturbances. In Tampa Bay, Florida, a nearly 35% loss of seagrass coverage occurred from the 1950s to the 2000s. This decline was primarily due to the effects of human population growth. To examine closely the continuing declining trend of this major indicator of the health of coastal ecosystems, a systematic approach for extracting seagrass patches using EO-1 Hyperion hyperspectral imagery has been developed. In our previous work, a method based on Locally Excitatory Globally Inhibitory Oscillator Networks (LEGION) was developed and successfully applied to military object recognition using hyperspectral and multispectral imagery. It showed great potential in target detection of hyperspectral imagery. In this work, it is extend and applied in seagrass extraction. This study i...

Mesoporous molecular sieves (MCM-41) was successfully synthesized using hydrothermal synthesis and characterized by X-ray diffraction and nitrogen adsorption–desorption. Characterization results show that synthesized MCM-41 is a good adsorption material of good crystallinity, large surface area (1,040m2/g) and uniform diameter (centered at 2.8 nm). Removal of Cr (VI) from aqueous solution using MCM-41 was carried out by UV-Vis spectrophotometry. The different parameters affecting the adsorption efficiency were investigated and obtained their optimal values (pH 4, temperature 35°C, initial Cr (VI) concentration < 10 mg/L, adsorption time 2 h, adsorbent concentration of 10mg/L). It is very useful and important to deal with Cr (VI) from aqueous solution. The adsorption isotherm was also investigated. It is found that the adsorption isotherm follows the Langmuir model better. What’s more, b of 76.71 mg-1 and q of 904 mg/g were calculated from Langmuir linear fitting. The adsorption reaction is spontaneous and...

The study of fifteen possible chemical reaction in the SiCl4 hydrogenation system in Siemens process based on the thermodynamic data for related pure compositions are reported in this paper. Curves of ΔGmθ-T for the 15 chemical reactions in the system have been fitted. The five independent reactions in the process have also been obtained and the relations of Κpθ and temperature have been fitted. Furthermore, diagrams of the equilibrium gas phase composition versus temperature under pressures of 1 atm, 3 atm, and 5 atm and feed mole ratios (χH2 / χSiCl4) of 2 : 1, 3 : 1, and 4 : 1 are present herein. Finally, the influencing factors (such as temperature, pressure and the feeding molar ratio) on the conversion ratio from SiCl4 to SiHCl3 have been studied. Diagrams of the η-conversion ratio are presented as a function of temperature, pressure and feed mole ratio, respectively. The optimum operation parameters in the actual production are determined by thermodynamic and kinetic studies. The results show that the conditions of 1100°C, 3 atm and feed mole ratio (χH2 / xSiCl4) of 4 : 1 are most preferable. Under these conditions, the conversion ratio from SiCl4 to SiHCl3 is 24.81%, contrary to the less than 20% in actual production.

The cost of solar-grade silicon cannot be reduced in the Siemens process, which is the major process of producing polycrystalline silicon through current technologies. Therefore, the zinc reduction process, which can reduce solar-grade silicon in a cost effective manner, should be redeveloped for these conditions. The thermodynamics in the zinc reduction process are studied in this paper. When the reactions reach equilibrium, the equilibrium gas phase composition has been analyzed within the temperature range of 1184 to 1500 K at nSiCl4/nZn of 1/2, 1/4, 1/8 and P = 1 atm, 3 atm and 6 atm. Furthermore, the relations of the production ratio of silicon and pressure, temperature and the feed molar ratio (nZn/nSiCl4) are investigated and the graphs thereof are plotted. The major side-reactions affecting the production ratio of silicon have been established as: SiCl4(g) + Zn(g) → SiCl2(g) + ZnCl2(g) and SiCl4(g) + Si(s) → SiCl2(g). Finally, suitable operational conditions in the practical process of poly-silicon manufacture have been established, with 1200 K, 2 atm and the feed molar ratio (nZn/nSiCl4) of 4 at the entrance is the best conditions. A production ratio of silicon of 90.3% is achieved under these conditions. Furthermore, 1184 K, 2 atm and the feed molar ratio (nZn/nSiCl4) of 4 are the ideal conditions. Under these conditions, the theoretical yield is 98%.

This paper investigates the geopositioning accuracy achievable from integrating IKONOS and QuickBird satellite stereo image pairs with aerial images acquired over a region at Tampa Bay, Florida. The results showed that the accuracy is related to a few factors of imaging geometry. For example, the geopositioning accuracy of a stereo pair of IKONOS or QuickBird images can be improved by integrating a set of aerial images, even just a single aerial image or a stereo pair of aerial images. Shorelines derived from the IKONOS and QuickBird stereo images, particularly the vertical positions, are compared with the corresponding observations of water-penetrating LiDAR and water gauge stations and proved that differences are within the limit of the geopositioning uncertainty of the satellite images.

Civil infrastructure objects are important elements in GIS applications. Due to the wide variety of object types, automatic recognition of infrastructure objects from imagery has been a challenging issue for the last two decades. Different approaches have been developed for recognition of buildings, one kind of infrastructure object most frequently dealt with in GIS. by defining and employing individual criteria. A Hopfield neural network can effectively combine different criteria in an overall network structure for a global optimization in finding object. In this paper we develop a holistic feature extraction approach including edge extraction, noise edge elimination by Gabor filters, contour extraction based on morphological operations, polygon simplification by local Hough transform, and building roof candidate selection using central contour sequence moment. In addition, shadows associated with buildings are extracted. This improved feature extraction approach greatly enhances the quality of ...

The shoreline is one of the most important features on earth's surface. It is valuable to a diverse user community. But the dynamic nature of the shoreline makes it difficult to be represented in a naturally dynamic style and to be utilized in applications. The officially used shoreline, for example in nautical charts, is the so-called tide-coordinated shoreline. It is also the shoreline that makes the computation of shoreline changes and associated environmental changes meaningful. Mapping of the tide-coordinated shoreline has been very costly. On the other hand, instantaneous shorelines extracted from different data sources may be available. Also, high-resolution satellite and airborne imagery have the capacity of stereo imaging and can be used to extract instantaneous shorelines at a high accuracy and low cost. This article proposes an approach to derivation of digital tidecoordinated shorelines from (a) those instantaneous shorelines and (b) digital coastal surface models and a digital water surface m...

This article introduces a mathematical model for photogrammetric processing of linear array stereo images acquired by high-resolution satellite imaging systems such as IKONOS. The experimental result of the generation of simulated IKONOS stereo images based on photogrammetric principles, IKONOS imaging geometry and a set of georeferenced aerial images is presented. An accuracy analysis of ground points derived from the simulated IKONOS stereo images is performed. The impact of the number of GCPs (ground control points), distribution of GCPs, and image measurement errors on the ground point accuracy is investigated. It is concluded that an accuracy of ground coordinates from 2 m to 3 m is attainable with GCPs, and 5 m to 12 m without GCPs. Two data sets of HRSC (high resolution stereo camera) and MOMS (modular opto-electronic multispectral stereo-scanner)-2P are also utilized to test the model and system. The presented data processing method is a key to the generation of mapping products such as digital te...

Coastal erosion presents a serious problem throughout U.S. coastal areas. The Ohio Geological Survey estimates that more than 3,200 acres of Ohio's Lake Erie shore have been lost to erosion since the 1870s, resulting in economic losses exceeding tens of millions of dollars per year. This article presents research results of a project that monitors shoreline erosion using high-resolution imagery and examines erosion causes. Spatial modeling and analysis methods are applied to the project area along the south shore of Lake Erie. The shoreline is represented as a dynamically-segmented linear model that is linked to a large amount of data describing shoreline changes. A new method computes an instantaneous shoreline using a digital water level model, a coastal terrain model, and bathymetric data. This method provides an algorithm for deriving the Mean-Lower Low Water (MLLW) and the Mean High Water (MHW) shorelines that are essential to navigation charts. The results describe a part of our effort towards a coa...

An UNderwater Digital Photogrammetric System (UNDIPS) has been developed jointly by The University of Calgary and Canadian Hydrographic Services (CHS). An underwater photogrammetric model considering the lens distortion, housing cover corrections, and the medium refraction has been developed. It corrects the displacements of image points caused by the distortion and refraction so that the photogrammetric processing can be treated as a reduced central perspective transformation and modified direct linear transformation (DLT) can be applied. The calibration of the system is performed in two phases. This allows the examination of characteristics of the system associated with the cameras, the housing covers, and the medium refractions separately. With the current configuration, the achievable accuracy of object points which are 2–2.5 m from the cameras in the object space is 0.3 cm in the x and y directions and 1.0 cm in the z direction (depth).

In geological subsurface modeling, large quantities of data are usually involved, which require extensive efforts to process using traditional methods. In addition, 3D representations and spatial operations are essential for computerised processing. With the recent advance in Geographic Information Systems (GIS) and computer technology, a wide range of spatial analysis and processing procedures for geological subsurface modeling are expected to be improved if 2D and 2.5D GIS functions are to be extended to handle 3D objects such as subsurface layers. This paper gives a brief description of a 3D system for modeling geological subsurface information developed at the Department of Geomatics Engineering, The University of Calgary. In this system, an octree data structure is employed to model 3D information due to its efficiency in Boolean operations, compactness in storing data and capability of intelligent data access. Surface representations are used for visualisation purposes. An algorithm for sea...

Geographic Information Systems (GIS) have been developed during the last decade. Their land‐based applications range from land information management, urban planning, and environmental research to engineering design and management in the utility and oil industries, geological subsurface analysis, and others. However, applications of GIS in the marine environment are still in the initial stages. This may be due to, among other things, the large marine data sets, the demands of 3D data processing, and the difficulty of ocean data acquisition. This article presents the result of the development of an integrated Marine Geographic Information System (MGIS) for the exploration and development of the Exclusive Economic Zone (EEZ) in the U.S. Pacific Islands region by the Pacific Mapping Center, University of Hawaii. Features such as spatial marine data processing, integration of GIS and mapping systems, 3D data structures, and simulation and animation of marine operations are developed and applied in th...

Shape from shading is one of the methods that derive geometric information of objects from analysis of monocular images. Application of this technique to underwater sonar images enables the conversion of imposed reflectance characteristics in sonar images to shape information, namely, slopes, about the seafloor surface. A combination of this shape information and available sparse distributed depth points results in improved dense bathymetric data. The reconstruction of shape models of seafloor surfaces from sonar images is treated as an inverse problem and is solved by the regularization theory. Sparse gridded points are used for boundary constraints. The regularization is implemented as a relaxation procedure with a hierarchical structure of multiresolution grids.

(1992). Correction of pixel locations of sidescan sonar images using bathymetric data acquired separately. Marine Geodesy: Vol. 15, No. 2-3, pp. 211-213.