High-resolution Topographic Information Research Articles

Habitat mapping as a tool for conservation and sustainable use of marine resources: Some perspectives from the MAREANO Programme, Norway

One of the main goals of marine spatial management is to promote a sustainable use of marine resources without putting biodiversity and habitats at risk.Environmental status assessments of benthic habitats have traditionally been conducted on soft bottom infauna communities. These communities represent only a limited part of the total diversity of seabed environments. Large and habitat forming organisms that are particularly vulnerable to physical disturbance of the seabed are in general associated with mixed or hard substrates. Together with mobile benthos these large organisms have been poorly mapped with the traditional approach. In accordance with a demand for information on all aspects of benthic habitats there is an increasing interest in a broader mapping approach for assessments of the distribution and status of benthos.This has led to an increased demand for a broader mapping approach for assessments of the distribution and status of benthos to include as many habitats as possible.We present mapping strategies based on literature together with perspectives from Norway's MAREANO Mapping Programme (www.mareano.no). A first and important step is to acquire high resolution topographical information from multibeam echosounder surveys. Building upon this baseline data set, video inspection along transects can provide information about how megafauna and surface sediments relate to local and broad scale topographical features. Classification of habitats/biotopes can be carried out through the analysis of the megafauna composition and its relation to environmental variables such as depth, quantitative terrain descriptors, and substrates. Marine landscapes have several definitions but generally refer to the major features delimiting broad-scale habitats. Each landscape will include different substrates that can be subdivided into smaller biotopes with specific fauna composition, functionality and production. For these habitats and biotopes information from all sampling gears can then be used to describe a more complete community composition.Experience from recent seafloor mapping indicates that a broad approach is required to support evidence-based policy and management of benthic species, communities and habitats. The approach presented can be used to identify biologically valuable areas and assess health status for bottom habitats/biotopes in a broad set of marine

Detecting Large-Scale Landslides Using Lidar Data and Aerial Photos in the Namasha-Liuoguey Area, Taiwan

Large-scale landslides often cause severe damage to lives and properties; therefore, their identification is essential in order to adopt proper mitigation measures. The objective of this study was to set up a methodological approach to help identify large-scale landslides using Lidar data, aerial photos and field investigation. The selected study areas were the Namasha and Liuoguey Areas in Kaohsiung City, Taiwan, both of which were severely hit by the Typhoon Morakot in 2009. The identification of large-scale landslides was performed based on Lidar high-resolution topographic information. The linear structures were mapped according to the shading map, with aspect in different azimuth to show good details of the structures. The scarps of the landslides were also identified. Validation of the results was done using both aerial photos and field investigations. In addition, stability analyses were performed on designated cases to further validate the results of Lidar identification.

Effect of Topographic Characteristics on Compound Topographic Index for Identification of Gully Channel Initiation Locations

<abstract><title><italic>Abstract.</italic></title> Sediment loads from gully erosion contribute to water quality problems, reduction in crop productivity by removal of nutrient-rich topsoil, and damage to downstream ecosystems. The identification of areas with high potential for gully channel development is often performed using spatially derived stream power estimates from second-order topographic indices, such as the compound topographic index (CTI). The utilization of CTI to identify where gullies develop is affected by field and local topographic characteristics and DEM resolution. In this study, the effect of overall terrain slope, local relief variance, and raster grid cell size on CTI cumulative distribution values was investigated using theoretical and observed catchment methodology. In the theoretical analysis, stochastic methods were used to generate simulated catchments to quantify the influence of overall terrain slope, local relief variance, and raster grid cell size (each considered individually). The observed methodology used three sites with distinct topographic characteristics, measured gully channels, and high-resolution topographic information. Raster grids for the three observed study sites were generated at varying raster grid cell sizes. Critical CTI values were determined through comparison of measured gully thalwegs with threshold CTI raster grids of the observed watersheds at different resolutions. Results from the theoretical investigation indicate that CTI values were linearly influenced by changes in relief variance and overall slope, while variations in raster grid cell size caused an inverse power variation in CTI values. In addition, variations in raster grid cell size, produced changes in cumulative distributions of the top 0.1% CTI values. The use of normalized CTI values (CTI_n) produced merged cumulative distribution curves when varying overall slope, terrain relief variance, and to a lesser degree DEM resolution. Similar findings were obtained from the analysis of observed catchments. When DEM resolution varied, the differences in critical CTI_n values in the same field were significantly reduced when compared to original critical CTI values, although differences were not fully eliminated. Normalization of the CTI cumulative distributions improved comparisons between different sites with distinct drainage area sizes and topographic characteristics, providing a possible alternative for investigations of large watersheds with more than one topographic characteristic. Results suggest that a normalized critical CTI between 1 and 2 could be used for the identification of areas with high potential for gully development. Knowing where gullies develop is important in understanding the effect of conservation practices on soil erosion through the use of field-scale and watershed-scale simulation models. Effective watershed management plans depend on this information to target the placement of conservation practices for the efficient use of available resources.

Atomic Force Microscopy of Connexin40 Gap Junction Hemichannels Reveals Calcium-dependent Three-dimensional Molecular Topography and Open-Closed Conformations of Both the Extracellular and Cytoplasmic Faces

Atomic force microscopy was used to study the three-dimensional molecular topography and calcium-sensitive conformational changes of Connexin40 hemichannels (connexons) reconstituted in 1,2-dioeloyl-sn-glycero-3-phosphatidylcholine lipid bilayers. Two classes of objects were observed that differed in their protrusion heights above the bilayer (2.6 versus 4.2 nm). Comparison to reconstituted connexons containing Connexin40 truncated to eliminate most of its C-terminal cytoplasmic domain showed that the two height classes corresponded to the shorter extracellular and taller cytoplasmic aspects of the hemichannels and that the C-terminal tail of Connexin40 contributes ∼1.6 nm in thickness. Hemichannels imaged in solutions containing < 10 μm Ca(2+) showed 3.1-3.2 nm depressions (openings) in 30% of the cytoplasmic faces and 65% of the extracellular faces, and high-resolution three-dimensional topography of extracellular or cytoplasmic aspects of some connexons was observed. After addition of 3.6 mm Ca(2+), > 75% of the connexons in either orientation adopted closed conformations. In contrast, hemichannels imaged in the presence of 0.1 mm EDTA showed large (5.6- to 5.8-nm diameter) openings in nearly all hemichannels regardless of orientation, and detailed topography was visible in many connexons. Real-time imaging following the addition of 3.6 mm Ca(2+) showed transitions of both extracellular and cytoplasmic orientations from "open" into "closed" conformations within several minutes. These studies provide the first high-resolution topographic information regarding a connexin with a large cytoplasmic domain and suggest that the extramembranous portions of Connexin40 contribute to a channel entrance that is relaxed by chelation of residual divalent cations.

Uncertainty of debris flow mobility relationships and its influence on the prediction of inundated areas

Empirical mobility relationships can be used for delineating debris flow inundated areas. A database of documented events in alpine mountain catchments of northeastern Italy is used to test the model DFlowz ( Berti and Simoni, 2007). We back-analyzed 25 DF events, ranging in volume from 3000 to 350,000 m 3, with the support of high resolution topographic information derived from LiDAR. The analysis makes use of an objective methodology for evaluating the accuracy of the predictions and involves the calibration of the model based on factors describing the uncertainty associated with the empirical relationships. Results indicate that the model is capable of reproducing the observed behavior with a maximum uncertainty of a factor of 3. The most relevant source of error lies in the estimation of the deposited volumes which affects the results of back-calculation and is mainly responsible also for the scatter associated with the empirical mobility relationships. On the contrary, the influence of different flow properties on the depositional process appears to play a minor role as the mutual relations between the three main scaling parameters (volume, inundated area, and cross-sectional area) are respected in the vast majority of cases and calibrated mobility coefficients show no significant relationship with the angle of reach of the deposit.

Multivariate forest structure modelling and mapping using high resolution airborne imagery and topographic information

Remote sensing has been widely used for modelling and mapping individual forest structural attributes, such as LAI and stem density, however the development and evaluation of methods for simultaneously modelling and mapping multivariate aspects of forest structure are comparatively limited. Multivariate representation of forest structure can be used as a means to infer other environmental attributes such as biodiversity and habitat, which have often been shown to be enhanced in more structurally diverse or complex forests. Image-based modelling of multivariate forest structure is useful in developing an understanding of the associations between different aspects of vertical and horizontal structure and image characteristics. Models can also be applied spatially to all image pixels to produce maps of multivariate forest structure as an alternative to sample-based field assessment. This research used high spatial resolution multispectral airborne imagery to provide spectral, spatial, and object-based information in the development of a model of multivariate forest structure as represented by twenty-four field variables measured in plots within a temperate hardwood forest in southern Quebec, Canada. Redundancy Analysis (RDA) was used to develop a model that explained a statistically significant proportion of the variance of these structural attributes. The resulting model included image variables representing mostly within-crown and within-shadow brightness variance (texture) as well as elevation, taken from a DEM of the study area. It was applied spatially across the entire study area to produce a continuous map of predicted multivariate forest structure. Bootstrapping validation of the model provided an RMSE of 19.9%, while independent field validation of mapped areas of complex and simple structure showed accuracies of 89% and 69%, respectively. Multiscale testing using resampled imagery suggested that the methods could possibly be used with current pan-sharpened, or future sub-metre resolution, multispectral satellite imagery, which would provide much greater spatial coverage and reduced image processing compared to airborne imagery.

지상 LiDAR를 이용한 만리포 해변 정밀 지형측량 및 지형 변화 분석

A terrestrial LiDAR was used to acquire precise and high-resolution topographical information of Malipo beach, Korea. Terrestrial LiDAR and RTK-DGPS (VRS) were mounted on top of a survey vehicle and used to scan 20 times stop-and-go method with 250 m spacing intervals at ebb tides. In total, 7 measurements were made periodically from 2008 to 2009 and after each beach replenishment event. We carried out GIS-based 3D spatial analysis such as slope and volume calculations in order to assess topographical changes over time. In relation to beach replenishment, comparative analysis of each volume change revealed them to be similar. This result indicates that the terrestrial LiDAR measurements are accurate and can be used to analyze temporal topographical changes. In conclusion, the methodology employed in this study can be used efficiently to exercise coastal management through monitoring and analyzing beach process such as erosion and deposition.

Transient deterministic shallow landslide modeling: Requirements for susceptibility and hazard assessments in a GIS framework

Application of transient deterministic shallow landslide models over broad regions for hazard and susceptibility assessments requires information on rainfall, topography and the distribution and properties of hillside materials. We survey techniques for generating the spatial and temporal input data for such models and present an example using a transient deterministic model that combines an analytic solution to assess the pore-pressure response to rainfall infiltration with an infinite-slope stability calculation. Pore-pressures and factors of safety are computed on a cell-by-cell basis and can be displayed or manipulated in a grid-based GIS. Input data are high-resolution (1.8 m) topographic information derived from LiDAR data and simple descriptions of initial pore-pressure distribution and boundary conditions for a study area north of Seattle, Washington. Rainfall information is taken from a previously defined empirical rainfall intensity–duration threshold and material strength and hydraulic properties were measured both in the field and laboratory. Results are tested by comparison with a shallow landslide inventory. Comparison of results with those from static infinite-slope stability analyses assuming fixed water-table heights shows that the spatial prediction of shallow landslide susceptibility is improved using the transient analyses; moreover, results can be depicted in terms of the rainfall intensity and duration known to trigger shallow landslides in the study area.

Nondestructive, High-Resolution Materials Characterization with the Confocal Raman-AFM

Abstract Materials research, biomedical research, and semiconductor manufacturing can all benefit from nondestructive, high-resolution methods of analysis. As most materials are heterogeneous, it is important to not only acquire high resolution topographic information, but also to identify the chemical composition of samples. A combination of high resolution microscopy with chemically sensitive spectroscopy combined in one instrument allows the detailed characterization of samples with different analytical techniques. When individual instruments are used, returning to a previously surveyed sample area can be very time consuming if not impossible without surface markers.

DEM AGGREGATION FOR WATERSHED MODELING1

ABSTRACT: The widely available USGS 7.5‐minute Digital Elevation Model (DEM) has a cell size of approximately 30 m × 30 m. This high resolution topographic information is impractical for many applications of distributed hydrologic and water quality models. In this study, cells were aggregated into coarse‐resolution areal units, termed grids, and a method to approximate flow direction for coarse‐resolution grids from 30 m DEM cells was developed. The method considers the flow path defined from the fine‐resolution DEM in determining a grid's flow direction and makes flow directions for grids closely follow the flow pattern suggested by the DEM. The aggregation method was applied to a DEM of Goodwater Creek, a nearly flat watershed that is located in central Missouri. The drainage networks derived for different levels of cell aggregations showed that grid aggregates of the Goodwater Creek watershed provided an adequate representation of the landscape topography.

Scanning near-field optical microscopy and microspectroscopy of green fluorescent protein in intact Escherichia coli bacteria

Scanning near-field optical microscopy (SNOM) yields high-resolution topographic and optical information and constitutes an important new technique for visualizing biological systems. By coupling a spectrograph to a near-field microscope, we have been able to perform microspectroscopic measurements with a spatial resolution greatly exceeding that of the conventional optical microscope. Here we present SNOM images of Escherichia coli bacteria expressing a mutant green fluorescent protein (GFP), an important reporter molecule in cell, developmental, and molecular biology. Near-field emission spectra confirm that the fluorescence detected by SNOM arises from bacterially expressed GFP molecules.

Demonstration of antigens at both sides of plasma membranes in one coincident electron microscopic image: a double-immunogold replica study of virus-infected cells.

We present here a procedure for obtaining high-resolution topographical information about the spatial distribution of antigens at both sides of isolated plasma membranes. HeLa cells grown on coverslips and infected with measles virus served as a model system. Virus glycoproteins appearing at the cell surface were demonstrated by tagging them with rabbit anti-measles antibodies and protein A-gold probes. Cells were stabilized with tannic acid, covered with a cationized coverslip, and then split in potassium-containing buffer. Membranes adherent to the cationized coverslip were fixed in formaldehyde-glutaraldehyde and reacted with mouse monoclonal antibodies against various structural proteins of measles virus. Antibody binding sites at the cytoplasmic surface were visualized either by the antibody bridge method, using normal mouse Ig coupled to gold colloid of different sizes, or by the peroxidase-antiperoxidase procedure. After osmication and critical point-drying, the cytoplasmic surfaces were replicated by platinum-carbon evaporation and examined by TEM without prior cleaning from biological material. This new method permits concomitant localization of antigens present at the inner and outer leaflets of the plasma membrane, and provides high-resolution information about the three-dimensional organization of the cytoplasmic surface.

High-resolution three-dimensional views of membrane-associated clathrin and cytoskeleton in critical-point-dried macrophages.

We obtained high-resolution topographical information about the distribution of clathrin and cytoskeletal filaments on cytoplasmic membrane surfaces of macrophages spreading onto glass coverslips by both critical-point drying of broken-open cells and preparation of rotary platinum replicas. Irregular patches of the adherent ventral surface of the plasma membrane were exposed in these cells, and large areas of these exposed membranes were covered with clathrin-coated patches, pits, and vesicles. Various amounts of cytoskeleton were attached to the plasma membranes of these spreading cells, either as distinct starlike foci, or as individual filaments and bundles radiating out from the cytoskeletal meshwork. In newly adherent cells a well developed Golgi-GERL complex, characterized by smooth, dish-like cisternae associated with rough endoplasmic reticulum, was observed. There were many coated vesicles budding off from the Golgi cisternae, and these were predominantly of the large type (150 nm) usually associated with the plasma membrane. In critical-point-dried samples, both cytoskeleton and membranes were preserved in detail comparable to that of quick-frozen samples, after appropriate fixation. Rotary replication of critical-point-dried cells provides a rapid, easily controlled, and generally easy to perform method for obtaining samples of exposed membrane large enough to permit quantification of membrane-associated clathrin and cytoskeleton under various experimental conditions.

Mars: Topographic control of clouds, 1907–1973

Mariner 9 high-resolution photos and topographic information were used to make a topographic analysis of “blue” and “red” cloud positions reported over a 66-year period in Lowell Observatory records. A sample of 77 “blue” cloud sites lay preferentially at the highest Martian elevations; 60% centered precisely on the seven major volcanic mountain peaks (unknown when the clouds were observed); another 16% lay on substantial slopes or contacts between cratered terrain and lower plains. The median altitude of blue cloud sites was 2.1 km above the global topographic median. These results agree with other evidence that most Earth-detected blue clouds are orographic uplift clouds, composed of condensates. Over half of 131 sporadic yellowish or red clouds were associated with blue clouds or volcanoes, and thus probably did not represent dust storm phenomena, contrary to a commonly held belief. Of 88 “possible dust clouds” (chosen by additional criteria), about two-thirds occur at borders between light and dark areas, in the light regions. These sites may have thin veneers of dust, and current depositional or denudational activity. Median altitude of “possible dust cloud” sites was 0.5 km below the global topographic median. Major dust storms begin in a few “core areas,” two of which associate with major basins Hellas and Isidis, probable reservoirs of mobile dust; but exact topographic control and causes of dust storms are unclear.

High-resolution topographical images of small metal particles

A technique to obtain high-resolution topographical information of particles in the Angstrom-size with a transmission electron microscope is described. This consists of obtaining dark-field images of particles which are tilted away from the Bragg angle and in a N-beam diffracting condition. The effective extinction distance is then substantially reduced and topographical analysis of the small crystallities can be obtained from Pendellösung fringes.

Photometric Reduction of Lunar Orbiter Video Tapes

The development of a system for the photometric reduction of Lunar Orbiter video magnetic tapes to obtain high-resolution topographic information of proposed Apollo landing sites was initiated by the Mapping Sciences Branch at the NASA Manned Spacecraft Center (MSC). The task of system design, hardware development, and integration (begun in late 1965) was assigned to the Information Systems Division of MSC The Computation and Analysis Division provided analyses of the programs and the development and operation of the system. This paper describes the system, its operational features, the special analysis techniques involved, results obtained to date, and continuing investigations.