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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...

As Antarctica attracts increasing attention in global climate change studies, the demand for field expeditions has increased in recent decades. Aircraft has become the most efficient mode of transportation because of the advantages of short travel times over long distances, access to unreachable locations and capability to carry different types of sensors to obtain large areal coverages. However, few studies have been published regarding Antarctic airfield site selection for heavy-wheeled aircraft. In this paper, we present methods and results of blue-ice airfield preliminary selection near Zhongshan station, East Antarctica. The geographic information system (GIS)-based method is supported by multi-mission high-resolution images from the ZY-3, WorldView-2 and Landsat-8 satellites along with existing remote sensing products. Ground truth observations were integrated with satellite panchromatic and spectral information to identify runway candidate areas. The information inferred by remote sensing data, including firn type, ice movement, surface slope and ice fracture, is used for evaluation of the airfield selection rules. Finally, the rankings and recommendations of runway candidates were performed in a GIS analysis environment. The site selection approach developed in this paper can be applied in preconstruction studies of other similar cryosphere environments to provide appropriate candidates for a final stage field investigation.

The Antarctic ice sheet is well known as the most sensitive and key issue in the global climate change research and is playing a more and more important role for the global sea level change. Measurement of changes in area and mass of the Antarctic ice sheet is critically important and has been made by using different remote sensing technologies and ground exploration data. Sequential mapping of Antarctic boundaries provides a simple and direct method for measuring the area and volume if ice sheet or ice shelves advances or retreats in the Antarctic coasts. Our results show that the total ice shelf area is retreated between 1963 and 2009. However, the trend for each ice shelf is quite different.

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...

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.

This technical note aims to provide a quick reference and some computational examples for the conversion between Antarctic ice-mass changes and global sea level equivalent (SLE) changes using a few assumptions that computationally simplify this complex problem and that acknowledge gaps in our knowledge of the Antarctic environment. A number of factors involved in the conversion process are discussed, and the sensitivity of the conversion result to certain aspects is analyzed. It was found that the global ocean area calculated from a recently improved global shoreline dataset has little impact on the uncertainty of the SLE estimation. SLE estimation using satellite gravity observations, such as those by GRACE, are sensitive to glacial isostatic adjustment (GIA) models. One more important result from the computation is that the effective density of the volume that is gained or lost during mass change may greatly affect the outcome of the conversion if it differs greatly from the actual density of the firn/i...

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...

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).

[1] During 6 years of continuous operations on the Martian surface, the Mars Exploration Rover (MER) Spirit has covered a traverse of approximately 7 km from the landing point to its current position at “Troy” near Home Plate. Localization of Spirit (and Opportunity) has been performed using two different methods: one that employs an incremental bundle adjustment (IBA) using rover imagery, and one that compares image features common to both a rover orthoimage and an orbital orthoimage. The IBA method continuously yields the desired 3-D rover positions at a very high level of accuracy and provides a simultaneous solution for high-quality topographic mapping of neighborhoods surrounding the rover. On the other hand, high-resolution orbital imagery can verify rover positions wherever the rover track is visible. Rapid rover localization on the orbital orthoimage is often achieved by comparing a rover orthoimage to the orbital orthoimage. In this paper, we present research results from a systematic comparison of these two localization methods over the entire length of the Spirit traverse. Two orbital orthoimages were generated from High Resolution Imaging Science Experiment (HiRISE) imagery. Integration of Mars Orbiter Laser Altimeter (MOLA) data into the HiRISE digital elevation model (DEM) and orthoimage generation was performed and proved to be effective in reducing large inconsistencies between MOLA and HiRISE data. This study found an overall difference of 1.5 percent of the traversed distance between the two sets of traverse positions derived using the two different localization methods. After a geometric transformation from one traverse to the other, the remaining inconsistency then represents the local differences between them and can be reduced to a level of less than 0.15 percent. Discussions of error sources and the strength and weakness of the methods are given. Scientific applications of the localization data are also briefly introduced.

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.

Spirit rover experienced significant slips traversing Husband Hill. This paper analyzes the slippage Spirit experienced from Sol 154 to Sol 737. Slippage with respect to terrain type and slope is computed using data downlinked from the rover, rover position, and orientation estimations from visual odometry (VO) and photogrammetry based bundle adjustment (BA) method. Accumulated slippage reached a maximum of 83.86 m on Sol 648. However, as Spirit descended into the Inner Basin, the direction of slippage reversed, and accumulated slippage approached zero by the end of the entire traverse. Eight local regions with significant slips and nineteen traverse segments have been analyzed. Slippage was found to be highly correlated to slope direction and magnitude; the reverse of slope directions in the ascending and descending portions of the traverse proves to be the main contributor to the observed cancellation of slippage. While the horizontal component of the slippage almost canceled out, the difference in elevation continually accumulated, mainly during the ascent. In general, long traverse segments created more slips than short ones. This is reflected in both the accumulated and individual slippages. In considering the four major Mars terrain types, Spirit performed best on bedrock, managing to drive on slopes close to 30°. Fine-grain surfaces were the most challenging; though progress was made on slopes up to 15°, slippages of over 100% (more slippage than distance traveled) occurred for short segments. The results of this work can be incorporate into a traverse planning framework in which rover slippage is minimized. Results can be employed in landed planetary missions for precision navigation to avoid potentially dangerous regions by considering expected slippage.

[1] Abundant wind-related features occur along Spirit's traverse into the Columbia Hills over the basaltic plains of Gusev Crater. Most of the windblown sands are probably derived from weathering of rocks within the crater, and possibly from deposits associated with Ma'adim Vallis. Windblown particles act as agents of abrasion, forming ventifacts, and are organized in places into various bed forms. Wind-related features seen from orbit, results from atmospheric models, and considerations of topography suggest that the general wind patterns and transport pathways involve: (1) winter nighttime winds that carry sediments from the mouth of Ma'adim Vallis into the landing site area of Spirit, where they are mixed with locally derived sediments, and (2) winter daytime winds that transport the sediments from the landing site southeast toward Husband Hill; similar patterns occur in the summer but with weaker winds. Reversals of daytime flow out of Gusev Crater and nighttime wind flow into the crater can account for the symmetry of the bed forms and bimodal orientations of some ventifacts.

[1] This paper presents the results of Mars topographic mapping and lander and rover localization for the Opportunity rover at Meridiani Planum during the Mars Exploration Rover (MER) 2003 mission. By Sol 458, the Opportunity rover traversed a distance of 5.20 km. We localized the lander using two-way Doppler radio positioning and cartographic triangulation of craters visible in both orbital and ground images. Additional high-resolution orbital images were taken to verify the determined lander position. Visual odometry and bundle adjustment techniques were applied to overcome wheel slippages, azimuthal angle drift, and other navigation errors (as large as 21% within Eagle crater). In addition, orbit-to-ground image-based adjustment was applied to correct rover location errors where bundle adjustment was not applicable. We generated timely topographic products, including orthoimages, digital terrain models (DTMs), three-dimensional (3-D) crater models, and rover traverse maps. In particular, detailed 3-D terrain models of major features, such as Endurance crater, have been generated using multisite panoramic stereo images based on bundle adjustment and wide baseline stereo technique.

The cratered plains of Gusev traversed by Spirit are generally low-relief rocky plains dominated by impact and eolian processes. Ubiquitous shallow, soil-filled, circular depressions, called hollows, are modified impact craters. Rocks are dark, fine-grained basalts, and the upper 10 m of the cratered plains appears to be an impact-generated regolith developed over intact basalt flows. Systematic field observations across the cratered plains identified vesicular clasts and rare scoria similar to original lava flow tops, consistent with an upper inflated surface of lava flows with adjacent collapse depressions. Crater and hollow morphometry are consistent with most being secondaries. The size frequency distribution of rocks >0.1 m diameter generally follows exponential functions similar to other landing sites for total rock abundances of 5-35%. Systematic clast counts show that areas with higher rock abundance and more large rocks have higher thermal inertia. Plains with lower thermal inertia have fewer rocks and substantially more pebbles that are well sorted and evenly spaced, similar to a desert pavement or lag. Eolian bed forms (ripples and wind tails) have coarse surface lags, and many are dust covered and thus likely inactive. Deflation of the surface _5-25 cm likely exposed two-toned rocks and elevated ventifacts and transported fines into craters creating the hollows. This observed redistribution yields extremely slow average erosion rates of _0.03 nm/yr and argues for very little long-term net change of the surface and a dry and desiccating environment similar to today's since the Hesperian (or _3 Ga).

[1] The Mars Exploration Rovers investigated numerous craters in Gusev crater and Meridiani Planum during the first ∼400 sols of their missions. Craters vary in size and preservation state but are mostly due to secondary impacts at Gusev and primary impacts at Meridiani. Craters at both locations are modified primarily by eolian erosion and infilling and lack evidence for modification by aqueous processes. Effects of gradation on crater form are dependent on size, local lithology, slopes, and availability of mobile sediments. At Gusev, impacts into basaltic rubble create shallow craters and ejecta composed of resistant rocks. Ejecta initially experience eolian stripping, which becomes weathering-limited as lags develop on ejecta surfaces and sediments are trapped within craters. Subsequent eolian gradation depends on the slow production of fines by weathering and impacts and is accompanied by minor mass wasting. At Meridiani the sulfate-rich bedrock is more susceptible to eolian erosion, and exposed crater rims, walls, and ejecta are eroded, while lower interiors and low-relief surfaces are increasingly infilled and buried by mostly basaltic sediments. Eolian processes outpace early mass wasting, often produce meters of erosion, and mantle some surfaces. Some small craters were likely completely eroded/buried. Craters >100 m in diameter on the Hesperian-aged floor of Gusev are generally more pristine than on the Amazonian-aged Meridiani plains. This conclusion contradicts interpretations from orbital views, which do not readily distinguish crater gradation state at Meridiani and reveal apparently subdued crater forms at Gusev that may suggest more gradation than has occurred.

[1] The impact basins of Mars reveal important insights on Martian tectonic evolution. They involve strongly disrupted, depressed regions of crust with likely enhanced porosity and permeability that may locally concentrate water and other crustal fluids. Hence the crustal properties of impact basins can also be important in the hunt for water and related clues for life on Mars. We assess the crustal details of impact basins by separating the Mars Global Surveyor free-air anomalies into terrain-correlated and terrain-decorrelated components. The separation is based on the correlation spectrum between the free-air anomalies and the gravity effects evaluated from the topography mapped by the Mars Orbital Laser Altimeter (MOLA). For topographically visible multiring basins like Isidis, striking circular patterns of alternating terrain-correlated free-air maxima and minima mark the uncompensated components of the central mantle plug and surrounding rings. The first vertical derivatives of these anomalies effectively estimate the basin ring locations and a transient cavity depth-to-diameter ratio of 0.09 that is consistent with the ratio observed for lunar nearside multiring basins. For the Isidis Basin we obtain an excavation depth of roughly 66 km that reflects considerably disrupted crust for concentrating local fluids since the Noachian impact. Furthermore, the related crustal terrain-decorrelated free-air anomalies suggest up to 2 km of high-density basin fill may cap the central basin. Subtle quasi-circular depressions in the relatively featureless MOLA terrain of the northern hemisphere have identified potentially buried impact basins [Frey et al., 2002]. An altimetry depression in Acidalia Planitia and another in Utopia are also associated with ringed patterns of terrain-decorrelated free-air anomalies that may mark the uncompensated mass effects of buried impact basins. The gravity-derived transient excavation depths for these inferred basins are roughly 41 and 20 km, respectively, while the related ring diameters (D) follow the ubiquitous D rule of planetary impact basins. The crust of these buried basins is likely to contain water at higher levels than the crust of the equatorial basins that was substantially dewatered with the development of the great northern basin. Hence analyzing surface fractures, faults, and other crustal discontinuities that can tap the more saturated crust of these inferred buried basins may facilitate the hunt for water on Mars.

[1] CAHVOR is a camera model used in machine vision for three-dimensional measurements. It models the transformation from the object domain to the image domain using vectors C, A, H, and V and corrects radial lens distortions with a vector O and a triplet R. In photogrammetric mapping the camera model is usually represented by collinearity equations with interior and exterior orientation parameters. In NASA's planetary missions the CAHVOR model has been widely used for rover navigation and scientific exploration. On the other hand, a photogrammetric model is often needed in mapping and photogrammetric data processing systems. This paper presents a method for conversions between the CAHVOR model and the photogrammetry model. A numerical example is given to validate the conversion equations.

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

There is a need to accurately link the water level to the shoreline vertical datum for various applications including coastal management, lake/river/estuary/wetland hydrological or storm surge modeling/forecasting. Coastal topography is historically surveyed and referenced to the predetermined vertical datum in terms of orthometric heights, or the heights above the geoid, which is poorly known in terms of accuracy and lack of adequate spatial resolution for coastal applications such as estuary or storm surge modeling. We demonstrate an accurate linking of the lake surface to a shoreline datum using satellite techniques, including GPS buoy and satellite altimetry, water level gauges, and local geoid and lake circulation models. The possible error sources are analyzed and an error budget is reported in this study. An innovated method to estimate geoid height near the water level gauge using a GPS buoy is proposed. It is found that at a 95% confidence interval, the method is consistent with the National Geodetic Survey GEOID03 geoid model. The lake surface represented using a lake circulation model provided by the Great Lakes Forecasting Systems is also verified with kriging based on the data (1999 - 2001) from the water level gauge, and TOPEX/POSEIDON altimeter. Mean discrepancies of 2.7 and 7.2 cm are found with the data from the gauges around Lake Erie, and from the combination of the gauges and the altimeter, respectively. It reveals that the current dominant limitation of more accurate linking of water surface to shoreline is the insufficient knowledge of geoid in the current models. Further improvement is feasible through more accurate and higher resolution modeling of the lake geoid.

[1] The planned 2003 Mars Exploration Rover (MER) Mission and follow-on surface activities associated with landed missions will focus on long distance roving and sample return, which require detailed knowledge of vehicle locations in both local and global reference systems. In this paper we argue that this rover localization should be known to within 0.1 of the distance traversed for local coordinate systems. To test the ability to meet this goal using only descent and rover-based data, we conducted experiments with simulated descent images and Field Integrated Design and Operations Rover data collected during field tests at Silver Lake, California, in April 1999. Specifically, an integrated bundle adjustment system incorporating both descent and rover-based images was developed and used to localize the rover positions. On the basis of surveyed ground control points it is demonstrated that the joint analysis produces RMS errors of 0.24, 0.15, and 0.38 m in x, y, and z% directions in a local coordinate system, respectively, for ground points within 500 m from the landing point and 0.23, 0.21, and 0.46 m within a distance of 1.5 km. Results show that it is possible to meet the 0.1 goal using descent and rover-based data only.