Browsing by Subject "LiDAR"
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Item Algorithms and Software Tools for Extracting Coastal Morphological Information from Airborne LiDAR Data(2010-07-14) Gao, YigeWith the ever increasing population and economic activities in coastal areas, coastal hazards have become a major concern for coastal management. The fundamental requirement of coastal planning and management is the scientific knowledge about coastal forms and processes. This research aims at developing algorithms for automatically extracting coastal morphological information from LiDAR data. The primary methods developed by this research include automated algorithms for beach profile feature extraction and change analysis, and an object-based approach for spatial pattern analysis of coastal morphologic and volumetric change. Automated algorithms are developed for cross-shore profile feature extraction and change analysis. Important features of the beach profile such as dune crest, dune toe, and beach berm crest are extracted automatically by using a scale-space approach and by incorporating contextual information. The attributes of important feature points and segments are derived to characterize the morphologic properties of each beach profile. Beach profiles from different time periods can be compared for morphologic and volumetric change analysis. An object-oriented approach for volumetric change analysis is developed to identify and delineate individual elevation change patches as discrete objects. A set of two-dimensional and three-dimensional attributes are derived to characterize the objects, which includes planimetric attributes, shape attributes, surface attributes, volumetric attributes, and summary attributes. Both algorithms are implemented as ArcGIS extension modules to perform the feature extraction and attribute derivation for coastal morphological change analysis. To demonstrate the utility and effectiveness of algorithms, the cross-shore profile change analysis method and software tool are applied to a case study area located at southern Monterey Bay, California, and the coastal morphology change analysis method and software tool are applied to a case study area located on Assateague Island, Maryland. The automated algorithms facilitate the efficient beach profile feature analysis over large geographical area and support the analysis of the spatial variations of beach profile changes along the shoreline. The explicit object representation of elevation change patches makes it easy to localize erosion hot spots, to classify the elevation changes caused by various mechanisms, and to analyze spatial pattern of morphologic and volumetric changes.Item Constructing a GIS-based 3D urban model using LiDAR and aerial photographs(Texas A&M University, 2005-02-17) Lin, Wei-MingDue to the increasing availability of high-resolution remotely sensed imagery and detailed terrain surface elevation models, urban planners and municipal managers can now model and visualize the urban space in three dimensions. The traditional approach to the representation of urban space is 2D planimetric maps with building footprints, facilities and road networks. Recently, a number of methods have been developed to represent true 3D urban models. Those include panoramic imaging, Virtual Reality Modeling Language (VRML), and Computer-aided Design (CAD). These methods focus on aesthetic representation, but they do not have sufficient spatial query and analytical capabilities. This research evaluates the conventional approaches to 3D urban models, and identifies their advantages and limitations; GIS functionalities have been combined with 3D urban visualization techniques to develop a GIS-based urban modeling method; The algorithms and techniques have been explored to derive urban objects and their attributes from airborne LiDAR and high-resolution imagery for constructing and visualizing 3D urban models; and 3D urban models for the Texas A&M University (TAMU) campus and downtown Houston have been implemented using the algorithms and techniques developed in this research. By adding close-range camera images and highresolution aerial photographs as the texture of urban objects, effect of photorealism visualization has been achieved for walk-through and fly-through animations. The Texas A&M University campus model and the downtown Houston model have been implemented to offer proof-of-concept, namely, to demonstrate the advantages of the GIS-based approach. These two prototype applications show that the GIS-based 3D urban modeling method, by coupling ArcGIS and MultiGen-Paradigm Site Builder 3D software, can realize the desired functionalities in georeferencing, geographical measurements, spatial query, spatial analysis, and numerical modeling in 3D visual environment.Item Development and Progression of Aeolian Blowouts in Padre Island National Seashore(2013-05-28) Jewell, Mallorie EThis study characterizes the development and migration of blowouts within Padre Island National Seashore (PAIS). A combination of aerial photographs and Light Detection and Ranging (LIDAR) are used to track the migration of eighteen blowouts, while Ground-penetrating Radar (GPR) is used to investigate the subsurface at two smaller sites in the study area. This data, coupled with beach morphology and changing anthropogenic factors, helps understand why the dune blowouts develop and are restricted to a particular section of the National Seashore. Aerial Photographs taken at least twice a decade since 1969 were used to track blowouts. Each blowout was digitized in order to understand its morphometric characteristics by studying its length, width, area, segmentation, perimeter, and the width of the neck, when present, through the foredune. The velocity and direction of movement were also calculated. Cluster analysis was used to analyze the blowouts using these morphological variables. Based on this data, blows appear to group into two morphologically different clusters. Blowouts grouped into Cluster 1 are longer, thinner, have smaller perimeters and areas, smaller throat widths, and are furthest from the beach access road. A lower dune elevation leads to a larger wave runup to crest height ratio. A larger ratio suggests that the dunes are more easily overtopped during large storms, thus scarping, a precursor to blowout development, is increased. Cluster 2 blowouts tend to be longer, wider, and stabilized faster leading to a more undulated perimeter in addition to a smaller wave runup potential due to a higher dune elevation. Historically blowouts covered the entire northern portion of PAIS. In the 1970?s the portion of the beach north of Park Road 22 was designated as non-driving. Since then all blowouts in this section have revegetated, while, blowouts in the driving section are still active. Beach driving pulverizes seaweed leading to less deposition along the dune toe and therefore a lower elevation of the backshore. As a result there is a greater wave runup in storms leading to an increase in susceptibility to scarping, and therefore, blowouts. Despite the fact that storms are the primary mechanism for blow development, anthropogenic effects, such as vehicle traffic, flatten the beach profile allowing for lower areas to become inundated during storms. This, along with decreased sediment budget and increased storm frequency increases the potential for blowouts to form events and leave the island vulnerable to an increased rate of sea level rise. GPR surveys were completed at two sites; an active blowout with a foredune that is not completely reestablished (Site 1) and a blowout that is stabilized by vegetation (Site 2). Six GPR surveys were completed at Site 1 and four surveys were completed at Site 2 that show the preservation of historic phases, surfaces, and facies used to interpret sequences and compare to aerial photography and LiDAR data. Site 1 moves through five phases that begin in 1969 and end at the present location, while Site 2 moves through three active phases and then ends in a fourth phase by becoming completely stabilized with vegetation in 2010.Item Estimating forest structural characteristics with airborne lidar scanning and a near-real time profiling laser systems(2009-05-15) Zhao, KaiguangLiDAR (Light Detection and Ranging) directly measures canopy vertical structures, and provides an effective remote sensing solution to accurate and spatiallyexplicit mapping of forest characteristics, such as canopy height and Leaf Area Index. However, many factors, such as large data volume and high costs for data acquisition, precludes the operational and practical use of most currently available LiDARs for frequent and large-scale mapping. At the same time, a growing need is arising for realtime remote sensing platforms, e.g., to provide timely information for urgent applications. This study aims to develop an airborne profiling LiDAR system, featured with on-the-fly data processing, for near real- or real- time forest inventory. The development of such a system involves implementing the on-board data processing and analysis as well as building useful regression-based models to relate LiDAR measurements with forest biophysical parameters. This work established a paradigm for an on-the-fly airborne profiling LiDAR system to inventory regional forest resources in real- or near real- time. The system was developed based on an existing portable airborne laser system (PALS) that has been previously assembled at NASA by Dr. Ross Nelson. Key issues in automating PALS as an on-the-fly system were addressed, including the design of an archetype for the system workflow, the development of efficient and robust algorithms for automatic data processing and analysis, the development of effective regression models to predict forest biophysical parameters from LiDAR measurements, and the implementation of an integrated software package to incorporate all the above development. This work exploited the untouched potential of airborne laser profilers for realtime forest inventory, and therefore, documented an initial step toward developing airborne-laser-based, on-the-fly, real-time, forest inventory systems. Results from this work demonstrated the utility and effectiveness of airborne scanning or profiling laser systems for remotely measuring various forest structural attributes at a range of scales, i.e., from individual tree, plot, stand and up to regional levels. The system not only provides a regional assessment tool, one that can be used to repeatedly, remotely measure hundreds or thousands of square kilometers with little/no analyst interaction or interpretation, but also serves as a paradigm for future efforts in building more advanced airborne laser systems such as real-time laser scanners.Item Forecasting Recovery Opportunities for the Red-cockaded Woodpecker on Private Lands in Eastern North Carolina Using a Spatial Model of Tree Age(2014-11-21) Dube, Amanda MCurrently, recovery efforts for the federally endangered red-cockaded woodpecker (RCW; Picoides borealis) primarily occur on public lands throughout the Southeast, where proven management practices ensure availability of mature, open pine savannahs able to support populations. Many populations on public lands are approaching carrying capacity, suggesting RCW management on private lands will become increasingly important to achieve recovery goals. Recovery on private lands will involve developing recruitment clusters through management practices that produce sufficient quality and spatial aggregation of trees age 60 or older to provide nesting habitat, and trees age 30 or older to provide foraging habitat, as outlined in the U.S. Fish and Wildlife Service (USFWS) Recovery Plan. In this analysis, relationships between tree age, canopy height, and site index were applied to land cover, LiDAR-derived canopy height, and expected site index data in a geographic information system (GIS) to produce a tree age model for pines on private lands in eastern North Carolina. Modeling provided a means to spatially and temporally identify recovery opportunities over the next 10 to 40 years, predict locations for potential recruitment clusters within the next 10 years, and assess connectivity between potential recruitment clusters. Depending on predominant species, modeling produced acceptable estimates for tree age and suitability timeframes for 69-95% and 85-92% of surveyed parcels, respectively, compared to expected age and suitability timeframes derived from field-collected diameter at breast height (DBH). Over 90% of existing RCW clusters on public lands were modeled to contain trees age 40 or older, suggesting age was underestimated in some cases. Results indicate almost 80% of existing pines will remain too young over the next 10 years to support RCW cavity trees. However, over 3,000 potential recruitment cluster sites were identified. These could contribute to increased carrying capacity by providing habitat for potential breeding groups, and create links between existing populations. The prevalence of young pines suggests more opportunities to create RCW recruitment clusters will become available over time with proper habitat and population management. Modeling such as done in this study can serve as a valuable conservation planning tool to guide recovery efforts over space and time.Item Geomorphic and anthropogenic influences on hydrologic connectivity along the lower Mississippi River(2012-12) Sounny-Slitine, Moulay Mohamed Anwar Adounia; Latrubesse, Edgardo; Hudson, Paul F; Dana, Peter HThis thesis examines geomorphic and anthropogenic factors in natural levee construction and presents a new digital elevation model extraction method for delineating natural levees. The method is applied to the lower Mississippi River to interpolate the elevation profile of the western natural levee. The resulting levee profile uncovers the complex nature of the bankfull stage level, which varies spatially along the length of the river in elevation. This profile is compared to human modifications of the river to show the morphology of the natural levee. While the levee may initially develop at a quick rate, the acceleration of growth slows over time due to lower stage-duration intervals. This leads to depressed levee systems and lower bankfull stage levels at sections of the river. These stages are used to model longitudinal hydrological connectivity between the river's main channel and the adjacent floodplain. High magnitudes of connectivity of 87% inundation occur with a 10% probability. These inundation models highlight the increased interaction that takes place between the river and its floodplain. It can be concluded that the modifications of the river’s channel in the form of cut-offs and revetments led to immature natural levees embanking the river, which are more prone to overbank processes and increase the frequency of inundation of the floodplain. This finding has significance to riparian conservation, planning, and engineering design, highlighting the lingering impacts of river engineering projects through increased hydrological connectivity.Item Modeling stormwater sewer systems using high resolution data(2014-05) Galdeano Alexandres, Carlos; Maidment, David R.More than 54% of the world population lives in urban areas, and this percentage is projected to increase rapidly in future years. This growth significantly affects the hydrological cycle, which translates into social and economic costs due to urban flooding. This thesis develops a procedure to evaluate the current storm water infrastructure using Airborne LiDAR data. This evaluation is essential to mitigate and prevent the effect of floods in urban areas. Airborne LiDAR data provides the elevation data necessary to characterize the elements involved in the storm water system. The processing of this data, digitization, and characterization of the storm drainage system is computed with ArcGIS, Geographic Information System (GIS) software. Scenarios for 4 return periods (2, 10, 25 and 100 years) are modeled using StormCAD in order to evaluate the capacity of the stormwater sewer system in the northwest area of The University of Texas at Austin main campus. The performance of the drainage system might work under strain for a 100-year storm event; therefore, it is suggested to modify the pipe sizes to prevent flooding in the area analyzed. The results indicate that the methodology proposed for evaluating the current conditions of a stormwater drainage system produces valid results, but can be improved using Ground-based LiDAR data.Item Patterns and paleoshorelines of White Sands Dune Field, New Mexico(2011-05) Baitis, Elke Elise; Kocurek, Gary; Mohrig, David; Helper, MarkThe dune field at White Sands, New Mexico, shows a well-defined pattern of dunes and interdune areas, as well as spatial variations in this pattern. The purpose of this research is to determine which measured pattern parameters are most consistent across the dune field and to determine the cause of depositional spatial variability. This was accomplished using an airborne LiDAR generated digital-elevation model (DEM) collected in June 2007 and covering 39 km² of the dune field. Properties of the dune field are defined by measurements from three dune populations: 1) 110 randomly selected dunes, 2) 247 dunes along transects oriented in the net transport direction, and 3) 171 dunes from three zones within the field where differences in pattern are visible. Measurements of eight common dune parameters show that the lowest coefficients of variation occur with dune orientation and crestline sinuosity, which largely define the field pattern. Cross-plotting of parameters shows generally poor correlations, which is thought to reflect variation around field-scale means that are comparable to other dune fields globally. Removing the dunes from the LiDAR DEM reveals a depositional substrate with breaks in slope interpreted as three paleoshorelines associated with Pleistocene Lake Otero. The paleoshorelines are antecedent boundary conditions that exert the primary control on spatial variability within the dune pattern.Item Sedimentological Reinterpretation of Surficial Unconsolidated Debris Flows and Stream Deposits of the Southern Flanks of Grand Mesa, CO: An Integrated LiDAR Approach(2014-08-08) Blakeley, Mitchell W.The southern slopes of Grand Mesa Colorado consist of glacio-fluvial sediments deposited when the Pleistocene ice cap draping Grand Mesa melted. Debris flows intermixed with braided and meandering stream deposits, were the focus of this study. This study developed a sedimentological description and interpretation of these deposits and tested the capabilities of terrestrial LiDAR (Light Detection and Ranging) for use in sedimentological studies. This research addressed the origin of the deposits south of Grand Mesa and evaluated the significance of terrestrial LiDAR for examination, description and interpretation of sedimentary facies at outcrop scale. The main outcrop exposed along highway 65 near Cory Grade, Colorado, was studied along with similar outcrops in the area. Field observations aided in calibrating interpretations from LiDAR scans and GigaPan? panoramic images. Facies were distinguished by grain size, depositional fabric, sedimentary structures and stratal geometries. Eight facies, making up three depositional environments were interpreted; Debris flows from the mesa, glacio-fluvial deposits from drainage of melt water, and fluvial deposits from the paleo Gunnison River. A stratigraphic column of the Cory Grade outcrop shows changes in depositional environments through time. This measured section aided in creation of facies models illustrating changing depositional environments. The first model illustrates the onset of melt sending large volumes of sediment in braided streams and outwash deposits. These north-south trending deposits are cross-cut by low sinuosity east-west trending abandoned channel and overbank deposits of the paleo Gunnison River. The second model illustrates that ice cap melt exposed a basalt cap and greater numbers of massive debris flows occurred. The ancestral Gunnison River continued to avulse and abandon channels, and with the increase in water and influx of sediment it migrated south to establish stable channels and banks. The third model suggests that once the ice cap melted, the lack of sediment from the north restricted river avulsion and small finger mesas were created. Additionally, with the lack of sediment from the mesa, the Gunnison River established a more permanent floodplain, and today flows south of the outcrops.Item Spatial Trends and Factors of Pimple Mound Formation in East-Central Texas(2012-07-16) Robinson, ChancePimple mounds are circular to elliptical domes with basal diameters ranging from 3 to more than 30 m, and heights of 30 cm to more than 2 m above intermound levels. For almost two centuries, the origin of these features has been speculated upon by scientists without general consensus as to one of over 30 different mechanisms suggested for their origin. These soil microfeatures can be observed throughout portions of East Texas as well as Louisiana, Arkansas, Oklahoma, and Missouri. Pimple mounds have been extensively mapped throughout East Texas as complexes covering over 1.0 million ha in 47 soil survey areas. About 600,000 ha are on Pleistocene-age geological formations. This study focused on 5,500 ha in Leon County, Texas, mapped as Rader-Derly complex and Derly-Rader complex. Rader (Aquic Paleustalfs) is on mounds and Derly (Typic Glossaqualfs) in the low intermounds. These soils are mapped primarily on terraces of the Trinity River system within the survey area. Using elevation levels published for the various fluviatile terrace deposits of the Trinity River, six groups (five terrace level groups and an upland group) were identified for analysis of mounds within the study area. Processes and factors of soil formation during the life of these features were considered using two methods ? remotely sensed elevation data and sampling data collected in the field. Size, shape, and relief of mounds were analyzed using airborne-based, remotely sensed LiDAR (Light Detection and Ranging) elevation data. Particle size distributions and pedon descriptions of mounds formed on materials of various ages were compared across the study area with special emphasis given to spatial trends. Analyses indicate a fluvial origin with pimple mound orientation corresponding to surrounding ridge and swale features of the paleoriver. Pimple mounds within the study area formed in the presence of sandy to loamy alluvial sediments and require the presence of accretionary ridge microtopography over point bar deposits. This alluvial parent material and topography were further developed by fluctuations in climate and vegetation over time. The erosional influence of bioturbation by animals and the intense rainfall and flood events which frequent the study area provided an environment in which these soil microfeatures have developed and over time exhibit increased levels of pedogenesis.Item Using LiDAR and normalized difference vegetation index to remotely determine LAI and percent canopy cover at varying scales(2009-05-15) Griffin, Alicia Marie RutledgeThe use of airborne LiDAR (Light Detection and Ranging) as a direct method to evaluate forest canopy parameters is vital in addressing both forest management and ecological concerns. The overall goal of this study was to develop the use of airborne LiDAR in evaluating canopy parameters such as percent canopy cover (PCC) and leaf area index (LAI) for mixed pine and hardwood forests (primarily loblolly pine, Pinus taeda, forests) of the southeastern United States. More specific objectives were to: (1) Develop scanning LiDAR and multispectral imagery methods to estimate PCC and LAI over both hardwood and coniferous forests; (2) investigate whether a LiDAR and normalized difference vegetation index (NDVI) data fusion through linear regression improve estimates of these forest canopy characteristics; (3) generate maps of PCC and LAI for the study region, and (4) compare local scale LiDAR-derived PCC and regional scale MODIS-based PCC and investigate the relationship. Scanning LiDAR data was used to derive local scale PCC estimates, and TreeVaW, a LiDAR software application, was used to locate individual trees to derive an estimate of plot-level PCC. A canopy height model (CHM) was created from the LiDAR dataset and used to determine tree heights per plot. QuickBird multispectral imagery was used to calculate the NDVI for the study area. LiDAR- and NDVI-derived estimates of plot-level PCC and LAI were compared to field observations for 53 plots over 47 square kilometers. Linear regression analysis resulted in models explaining 84% and 78% of the variability associated with PCC and LAI, respectively. For these models to be of use in future studies, LiDAR point density must be 2.5 m. The relationship between regional scale PCC and local scale PCC was investigated by resizing the local scale LiDAR-derived PCC map to lower resolution levels, then determining a regression model relating MODIS data to the local values of PCC. The results from this comparison showed that MODIS PCC data is not very accurate at local scales. The methods discussed in this paper show great potential for improving the speed and accuracy of ecological studies and forest management.