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Articles 1 - 21 of 21
Full-Text Articles in Physical Sciences and Mathematics
Seafloor Characterization From Spatial Variation Of Multibeam Backscatter Vs. Grazing Angle, Tianhang Hou, Lloyd C. Huff, Yuri Rzhanov, Larry A. Mayer
Seafloor Characterization From Spatial Variation Of Multibeam Backscatter Vs. Grazing Angle, Tianhang Hou, Lloyd C. Huff, Yuri Rzhanov, Larry A. Mayer
Center for Coastal and Ocean Mapping
Backscatter vs. grazing angle, which can be extracted from multibeam backscatter data, depend on characteristics of the multibeam system and the angular responses of backscatter that are characteristic of different seafloor properties, such as sediment hardness and roughness. Changes in backscatter vs. grazing angle that are contributed by the multibeam system normally remain fixed over both space and time. Therefore, they can readily be determined and removed from backscatter data. The variation of backscatter vs. grazing angle due to the properties of sediments will vary from location to location, as sediment type changes. The sediment component of variability can be …
Improvement To The International Bathymetric Chart Of The Arctic Ocean (Ibcao): Updating The Data Base And The Grid Model, Martin Jakobsson, Norman Cherkis
Improvement To The International Bathymetric Chart Of The Arctic Ocean (Ibcao): Updating The Data Base And The Grid Model, Martin Jakobsson, Norman Cherkis
Center for Coastal and Ocean Mapping
The project to develop the IBCAO grid model was initiated in 1997 with the objective of providing to the Arctic research community an improved portrayal of the seabed north of 64-deg N, in a form suitable for digital manipulation and visualization. The model was constructed from a compilation of all single-beam and multibeam echo soundings that were available for the polar region, complemented where appropriate by newly released contour information. The grid features a cell size of 2.5 x 2.5 km on a polar stereographic projection; it is constructed on the WGS 84 datum, with true scale at 75-deg N. …
Volumes And Areas Of Early Weichselian Ice Dammed Lakes In Northern Russia, Martin Jakobsson, Jan Mangerud, Valery Astakov, John Inge Svendsen
Volumes And Areas Of Early Weichselian Ice Dammed Lakes In Northern Russia, Martin Jakobsson, Jan Mangerud, Valery Astakov, John Inge Svendsen
Center for Coastal and Ocean Mapping
No abstract provided.
Harmonising Chart And Navigation-Related Information On Ecdis, Lee Alexander
Harmonising Chart And Navigation-Related Information On Ecdis, Lee Alexander
Center for Coastal and Ocean Mapping
ECDIS is a real-time navigation system that integrates a variety of chart and navigation-related information. More than simply a replacement for a paper nautical chart, ECDIS is capable of continuously determining a vessel's position in relation to land, charted objects, aids-to-navigation, and unseen hazards. Increasingly, ECDIS is being used for both navigation and collision-avoidance tasks. There is growing concern about the display of ever-increasing amounts of both chart and navigation-related information. When it comes to using ECDIS, displaying more information is not necessarily better. Too much information (i.e., clutter) may only lead to confusion. In this regard, there is need …
Hypsometry And Volume Of The Arctic Ocean And Its Constituent's Seas, Martin Jakobsson
Hypsometry And Volume Of The Arctic Ocean And Its Constituent's Seas, Martin Jakobsson
Center for Coastal and Ocean Mapping
No abstract provided.
Ecdis Development Laboratory And Navigation Technology Demonstration Center, Lee Alexander, Maxim F. Van Norden, Charles M. Fralick
Ecdis Development Laboratory And Navigation Technology Demonstration Center, Lee Alexander, Maxim F. Van Norden, Charles M. Fralick
Center for Coastal and Ocean Mapping
The U.S. Navy is undergoing a major transition from traditional, paper chart navigation to computer-based electronic charting. The Chief of Naval Operations (CNO) has mandated that all Navy ships will navigate strictly through electronic means by FY07. However, due to some recent groundings, the Navy is now striving to accelerate the full implementation of electronic navigation by FY04. The Naval Oceanographic Office (NAVOCEANO) is making a concerted effort to support this transition with upgrades to state-of-the-art survey ships, instrumentation, and data processing equipment. NAVOCEANO is increasing its capability to rapidly collect and process hydrographic survey data, and to quickly produce …
Field Evaluation Of Sounding Accuracy In Deep Water Multibeam Swath Bathymetry, Christian De Moustier
Field Evaluation Of Sounding Accuracy In Deep Water Multibeam Swath Bathymetry, Christian De Moustier
Center for Coastal and Ocean Mapping
A new Kongsberg-Simrad EM120 multibeam echo-sounder has been installed aboard Scripps Institution of Oceanography's Research Vessel Roger Revelle in January 2001. This system can map reliably a 20 km swath of seafloor in 4000 m water depth with 191 soundings per ping. Such a wide swath width demands highly accurate (<0.05' RMS) roll information from a motion sensor, and makes estimating sounding accuracy across the swath an interesting challenge. It is shown that good accuracy estimates can be obtained by collecting data on station under control of the GPS-aided dynamic positioning system usually available on most modern long-range oceanographic vessels. A number of motion sensors, with RMS roll accuracy specifications ranging from 0.05' to 0.01' ,were tested with the EM120 sonar on station in 3800 m to 4000 m water depths. Unexpectedly, they yielded roughly the same depth uncertainty as a function of receive beam angle. This result might be explained by synchronization errors between the attitude data and the sonar data leading to beam pointing errors, other types of beam pointing errors, a range of roll accuracy narrower than specified for the motion sensors, or a combination of these factors
Geozui3d: Data Fusion For Interpreting Oceanographic Data, Colin Ware, Matthew D. Plumlee, Roland J. Arsenault, Larry A. Mayer, Shep M. Smith Lt, Donald H. House
Geozui3d: Data Fusion For Interpreting Oceanographic Data, Colin Ware, Matthew D. Plumlee, Roland J. Arsenault, Larry A. Mayer, Shep M. Smith Lt, Donald H. House
Center for Coastal and Ocean Mapping
GeoZui3D stands for Geographic Zooming User Interface. It is a new visualization software system designed for interpreting multiple sources of 3D data. The system supports gridded terrain models, triangular meshes, curtain plots, and a number of other display objects. A novel center of workspace interaction method unifies a number of aspects of the interface. It creates a simple viewpoint control method, it helps link multiple views, and is ideal for stereoscopic viewing. GeoZui3D has a number of features to support real-time input. Through a CORBA interface external entities can influence the position and state of objects in the display. Extra …
Derivation Of Del180 From Sediment Core Log Data' Implications For Millennial-Scale Climate Change In The Labrador Sea, M. E. Weber, Larry A. Mayer, C. Hillaire-Marcel, G. Bilodeau, F. Rack, R. N. Hiscott, A. E. Aksu
Derivation Of Del180 From Sediment Core Log Data' Implications For Millennial-Scale Climate Change In The Labrador Sea, M. E. Weber, Larry A. Mayer, C. Hillaire-Marcel, G. Bilodeau, F. Rack, R. N. Hiscott, A. E. Aksu
Center for Coastal and Ocean Mapping
Sediment core logs from six sediment cores in the Labrador Sea show millennial-scale climate variability during the last glacial by recording all Heinrich events and several major Dansgaard-Oeschger cycles. The same millennial-scale climate change is documented for surface water δ18O records of Neogloboquadrina pachyderma (left coiled); hence the surface water δ18O record can be derived from sediment core logging by means of multiple linear regression, providing a paleoclimate proxy record at very high temporal resolution (70 years). For the Labrador Sea, sediment core logs contain important information about deepwater current velocities and also reflect the variable …
Sensor-Assisted Video Mosaicing For Seafloor Mapping, Yuri Rzhanov, Randy G. Cutter Jr., Lloyd C. Huff
Sensor-Assisted Video Mosaicing For Seafloor Mapping, Yuri Rzhanov, Randy G. Cutter Jr., Lloyd C. Huff
Center for Coastal and Ocean Mapping
This paper discusses a proposed processing technique for combining video imagery with auxiliary sensor information. The latter greatly simplifies image processing by reducing complexity of the transformation model. The mosaics produced by this technique are adequate for many applications, in particular habitat mapping. The algorithm is demonstrated through simulations and hardware configuration is described.
Improvement Of Image Alignment Using Camera Attitude Information, Yuri Rzhanov, Lloyd C. Huff, Randy G. Cutter Jr.
Improvement Of Image Alignment Using Camera Attitude Information, Yuri Rzhanov, Lloyd C. Huff, Randy G. Cutter Jr.
Center for Coastal and Ocean Mapping
We discuss a proposed technique for incorporation of information from a variety of sensors in a video imagery processing pipeline. The auxiliary information allows one to simplify computations, effectively reducing the number of independent parameters in the transformation model. The mosaics produced by this technique are adequate for many applications, in particular habitat mapping. The algorithm, demonstrated through simulations and hardware configuration, is described in detail
Moving Icons, Detection And Distraction, Lyn Bartram, Colin Ware, Tom Calvert
Moving Icons, Detection And Distraction, Lyn Bartram, Colin Ware, Tom Calvert
Center for Coastal and Ocean Mapping
Simple motion has great potential for visually encoding information but there are as yet few experimentally validated guidelines for its use. Two studies were carried out to look at how efficiently simple motion cues were detected and how distracting they were in different task contexts. The results show that motion outperforms static representations and identify certain types of motions which are more distracting and irritating than others.
Error Estimation Of Bathymetric Grid Models Derived From Historic And Contemporary Data Sets, Martin Jakobsson, Brian R. Calder, Larry A. Mayer, Andy Armstrong
Error Estimation Of Bathymetric Grid Models Derived From Historic And Contemporary Data Sets, Martin Jakobsson, Brian R. Calder, Larry A. Mayer, Andy Armstrong
Center for Coastal and Ocean Mapping
The past century has seen remarkable advances in technologies associated with positioning and the measurement of depth. Lead lines have given way to single beam echo sounders, which in turn are being replaced by multibeam sonars and other means of remotely and rapidly collecting dense bathymetric datasets. Sextants were replaced by radio navigation, then transit satellite, GPS and now differential GPS. With each new advance comes tremendous improvement in the accuracy and resolution of the data we collect. Given these changes and given the vastness of the ocean areas we must map, the charts we produce are mainly compilations of …
Automatic Detection Of Outliers In Multibeam Echo Sounding Data, Tianhang Hou, Lloyd C. Huff, Larry A. Mayer
Automatic Detection Of Outliers In Multibeam Echo Sounding Data, Tianhang Hou, Lloyd C. Huff, Larry A. Mayer
Center for Coastal and Ocean Mapping
The data volumes produced by new generation multibeam systems are very large, especially for shallow water systems. Results from recent multibeam surveys indicate that the ratio of the field survey time, to the time used in interactive editing through graphical editing tools, is about 1:1. An important reason for the large amount of processing time is that users subjectively decide which soundings are outliers. There is an apparent need for an automated approach for detecting outliers that would reduce the extensive labor and obtain consistent results from the multibeam data cleaning process, independent of the individual that has processed the …
Robust Automatic Multi-Beam Bathymetric Processing, Brian R. Calder, Larry A. Mayer
Robust Automatic Multi-Beam Bathymetric Processing, Brian R. Calder, Larry A. Mayer
Center for Coastal and Ocean Mapping
No abstract provided.
Geographic Information Systems Tools For Collecting And Accessing Arctic Bathymetry: International Bathymetric Chart Of The Arctic Ocean, Martin Jakobsson
Geographic Information Systems Tools For Collecting And Accessing Arctic Bathymetry: International Bathymetric Chart Of The Arctic Ocean, Martin Jakobsson
Center for Coastal and Ocean Mapping
No abstract provided.
Physiography And Late Quaternary-Holocene Processes Of Northeastern Gulf Of Mexico Outer Continental Shelf Off Mississippi And Alabama, James V. Gardner, Peter Dartnell, Kenneth J. Sulak, Brian R. Calder, Laurent Hellequin
Physiography And Late Quaternary-Holocene Processes Of Northeastern Gulf Of Mexico Outer Continental Shelf Off Mississippi And Alabama, James V. Gardner, Peter Dartnell, Kenneth J. Sulak, Brian R. Calder, Laurent Hellequin
Center for Coastal and Ocean Mapping
High-resolution multibeam mapping of the mid- and outer continental shelf and upper slope off Mississippi and Alabama reveals a complex bathymetry that reflects conditions during the last eustatic rise and the present high stand of sea level. The most prominent bathymetric features are pinnacles and hardgrounds that are scattered throughout the area. These features generally stand <10 m above the surrounding seafloor, cover large areas, and display a variety of morphologies. Almost all the reef pinnacles and hardgrounds have zones of high acoustic backscatter on their summits and on the seafloor immediately adjacent to their southwest walls. In addition, they also have erosional moats on the seafloor to the southwest. Large fields of bedforms are scattered throughout the mapped area. The asymmetries and orientations of the bedforms suggest that they were formed by excursions of the northeast-flowing Loop Current. In contrast, the pervasive ponding of sediment on the northeast sides of bathymetric highs indicates that one of the predominant directions of sediment transport has been to the south and southwest. The shelf break is a zone of numerous landslides of various sizes and complexities. The morphology of several landslide scars indicates that some of the failures occurred recently. One large reef-capped salt dome was mapped in the area, surrounded by a large field of pock-marks. Fields of pockmarks are also scattered on the shelf. The growth and demise of the reefs are related to the fluctuating transgression of eustatic sea level during the last deglaciation. Two episodes of reef drowning are correlated with the increased rates of sea-level rise during documented melt-water pulses; the first occurred from 14.8 to 14.2 ka and the second from 11.8 to 11.2 ka. Rates of sea-level rise exceeded the maximum growth rate of hermatypic corals only during these two intervals since the last glacial maximum and thus drowned the coral communities.
On The Estimation Of Errors In Gridded Bathymetric Compilations, Martin Jakobsson, Brian R. Calder, Larry A. Mayer, Andy Armstrong
On The Estimation Of Errors In Gridded Bathymetric Compilations, Martin Jakobsson, Brian R. Calder, Larry A. Mayer, Andy Armstrong
Center for Coastal and Ocean Mapping
No abstract provided.
The Maximum Extent Of The Saalian And Weichselian Glaciations In Eurasis, John Inge Svendsen, Valery Astakov, H Alexanderson, I Demidov, Julian A. Dowdeswell, V. Gataulin, M Henriksen, C Hjort, H W. Hubberten, Martin Jakobsson, M Houmark-Nielsen, K H. Kajeer, E Larsen, J P. Lunkka, Jan Mangerud, A D. Matiouchkov, Per Moller, M Siegert, C Siegert, M Saarnisto, O Maslenikova
The Maximum Extent Of The Saalian And Weichselian Glaciations In Eurasis, John Inge Svendsen, Valery Astakov, H Alexanderson, I Demidov, Julian A. Dowdeswell, V. Gataulin, M Henriksen, C Hjort, H W. Hubberten, Martin Jakobsson, M Houmark-Nielsen, K H. Kajeer, E Larsen, J P. Lunkka, Jan Mangerud, A D. Matiouchkov, Per Moller, M Siegert, C Siegert, M Saarnisto, O Maslenikova
Center for Coastal and Ocean Mapping
No abstract provided.
Martha's Vineyard Survey: Data Collected By Bill Schwab And Bill Danforth - Usgs, Larry A. Mayer
Martha's Vineyard Survey: Data Collected By Bill Schwab And Bill Danforth - Usgs, Larry A. Mayer
Center for Coastal and Ocean Mapping
No abstract provided.
Surficial Backscatter Of The Eel River Margin: It's Just Gas!, Luciano E. Fonseca, Larry A. Mayer, Neal Driscoll, Dan Orange, Janet Yun
Surficial Backscatter Of The Eel River Margin: It's Just Gas!, Luciano E. Fonseca, Larry A. Mayer, Neal Driscoll, Dan Orange, Janet Yun
Center for Coastal and Ocean Mapping
No abstract provided.