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- 摘要
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- 实验方案
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Use of DEMs Derived from TLS and HRSI Data for Landslide Feature Recognition
摘要： This paper addresses the problems arising from the use of data acquired with two different remote sensing techniques—high-resolution satellite imagery (HRSI) and terrestrial laser scanning (TLS)—for the extraction of digital elevation models (DEMs) used in the geomorphological analysis and recognition of landslides, taking into account the uncertainties associated with DEM production. In order to obtain a georeferenced and edited point cloud, the two data sets require quite different processes, which are more complex for satellite images than for TLS data. The differences between the two processes are highlighted. The point clouds are interpolated on a DEM with a 1 m grid size using kriging. Starting from these DEMs, a number of contour, slope, and aspect maps are extracted, together with their associated uncertainty maps. Comparative analysis of selected landslide features drawn from the two data sources allows recognition and classification of hierarchical and multiscale landslide components. Taking into account the uncertainty related to the map enables areas to be located for which one data source was able to give more reliable results than another. Our case study is located in Southern Italy, in an area known for active landslides.
关键词： kriging,Geo-Eye-1,TLS,morphometric feature,HRSI,uncertainty,DEM
更新于2025-09-23 15:22:29
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Pléiades Tri-Stereo Data for Glacier Investigations—Examples from the European Alps and the Khumbu Himal
摘要： In this study, we use Pléiades tri-stereo data to generate a digital elevation model (DEM) from the Pléiades images using a workflow employing semi-global matching (SGM). We examine the DEM accuracy in complex mountain glaciated terrain by comparing the new DEMs with an independent high-quality DEM based on airborne laser scanning (ALS) data for a study area in the Austrian Alps, and with ground control points for a study area in the Khumbu Himal of Nepal. The DEMs derived using the SGM algorithm compare well to the independent high-quality ALS DEM, and the workflow produces models of sufficient quality to resolve ground control points, which are based on Pléiades imagery that are of sufficient quality to perform high spatio-temporal resolution assessments of remote areas for which no field data is available. The relative accuracy is sufficient to investigate glacier surface elevation changes below one meter, and can therefore be applied over relatively short periods of time, such as those required for annual and seasonal assessments of change. The annual geodetic mass balance for the Alpine case derived from our DEM compares well to the glaciological mass balance, and multitemporal DEM analysis is used to resolve the seasonal changes of five glaciers in the Khumbu Himal, revealing that glaciological processes such as accumulation, ablation, and glacier movement mainly take place during the summer season, with the winter season being largely inactive in the year sampled.
关键词： Khumbu Himal,semi-global matching,Pléiades tri-stereo data,surface change,optical satellite data,DEM,glaciers
更新于2025-09-23 15:22:29
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Phasor Quaternion Neural Networks for Singular Point Compensation in Polarimetric-Interferometric Synthetic Aperture Radar
摘要： Interferograms obtained by synthetic aperture radar often include many singular points (SPs), which makes it difficult to generate an accurate digital elevation model. This paper proposes a filtering method to compensate SPs adaptively by using polarization and phase information around the SPs. Phase value is essentially related to polarization changes in scattering as well as propagation. In order to handle the polarization and phase information simultaneously in a consistent manner, we define a new number, phasor quaternion (PQ), by combining quaternion and complex amplitude, with which we construct the theory of PQ neural networks (PQNNs). Experiments demonstrate that the proposed PQNN filter compensates SPs very effectively. Even in the situations where the conventional methods deteriorate in their performance, it realizes accurate compensation, thanks to its good generalization characteristics in integrated Poincare-sphere polarization space and the complex-amplitude space. We find that PQNN is an excellent framework to deal with the polarization and phase of electromagnetic wave adaptively and consistently.
关键词： Complex-valued neural network (CVNN),phase singular point,polarimetric interferometric synthetic aperture radar (PolInSAR),quaternion neural network (QNN),digital elevation model (DEM)
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - Shenzhen, China (2018.7.13-2018.7.15)] 2018 IEEE 3rd International Conference on Signal and Image Processing (ICSIP) - Interferometric SAR Baseline Estimation by Partitioned High Coherence Areas
摘要： In this article, a novel interferometric synthetic aperture radar (InSAR) baseline estimation method based on ground control points (GCPs) and partitioning is proposed. Instead of introducing the existing low-resolution digital elevation model (DEM) to correct the phase jumps between high and low coherence regions in the process of phase unwrapping, we use the high coherence regional block to calibrate the interferometric parameters. In the process of calibration, the GCPs can reference for low resolution DEM, also can be obtained through the filed measurement. Because the interferometric parameters calibration does not change the absolute phase, which avoids the local DEM restriction by low resolution DEM. In addition, the block based on the coherence map avoids DEM inversion error due to overall absolute phase deviation. Gaofen-3 InSAR data of Ningbo area are used to verify the effectiveness of the proposed method.
关键词： baseline estimation,DEM,InSAR
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Multi-Pass SAR Interferometry for 3D Reconstruction of Complex Mountainous Areas Based on Robust Low Rank Tensor Decomposition
摘要： During the past decades, multi-pass SAR interferometry (InSAR) techniques have been developed for retrieving geophysical parameters such as elevation, over large areas. Conventional method such as periodogram usually requires a fairly large SAR image stack (usually in the order of tens), in order to achieve reliable estimates of these parameters. However, when it comes to large-area processing, it is time-consuming and luxury to obtain a sufficient number of SAR images for the reconstruction. In this paper, we demonstrate a novel multi-pass InSAR method for 3D reconstruction using low rank tensor decomposition. By exploiting the low rank prior knowledge in the multi-pass InSAR stack, simulations show that the proposed method can improve the accuracy of elevation estimates by a factor of two, compared to the state-of-the-art InSAR filtering methods, such as SqueeSAR. The capability of the proposed algorithm is also demonstrated on real data using one TanDEM-X InSAR stack of a complex mountainous area.
关键词： Multi-pass InSAR,TanDEM-X,DEM,Low Rank
更新于2025-09-23 15:22:29
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Evaluation of Ground Surface Models Derived from Unmanned Aerial Systems with Digital Aerial Photogrammetry in a Disturbed Conifer Forest
摘要： Detailed vertical forest structure information can be remotely sensed by combining technologies of unmanned aerial systems (UAS) and digital aerial photogrammetry (DAP). A key limitation in the application of DAP methods, however, is the inability to produce accurate digital elevation models (DEM) in areas of dense vegetation. This study investigates the terrain modeling potential of UAS-DAP methods within a temperate conifer forest in British Columbia, Canada. UAS-acquired images were photogrammetrically processed to produce high-resolution DAP point clouds. To evaluate the terrain modeling ability of DAP, first, a sensitivity analysis was conducted to estimate optimal parameters of three ground-point classification algorithms designed for airborne laser scanning (ALS). Algorithms tested include progressive triangulated irregular network (TIN) densification (PTD), hierarchical robust interpolation (HRI) and simple progressive morphological filtering (SMRF). Points were classified as ground from the ALS and served as ground-truth data to which UAS-DAP derived DEMs were compared. The proportion of area with root mean square error (RMSE) <1.5 m were 56.5%, 51.6% and 52.3% for the PTD, HRI and SMRF methods respectively. To assess the influence of terrain slope and canopy cover, error values of DAP-DEMs produced using optimal parameters were compared to stratified classes of canopy cover and slope generated from ALS point clouds. Results indicate that canopy cover was approximately three times more influential on RMSE than terrain slope.
关键词： Structure from Motion (SfM),point cloud classification,unmanned aerial systems (UAS),digital elevation model (DEM)
更新于2025-09-23 15:22:29
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Deformation of Bhuj Earthquake Area Obtained with Persistent Scatterer Interferometric Analysis of Alos L-Band Sar Data
摘要： Long-term ground surface displacements of seismically active Bhuj area in India between two time spans are derived from L-band ALOS-1 and ALOS-2 images using Persistent Scatterer Interferometry approach. The work also focuses on studying the influence of high resolution TanDEM-X Global DEM on topographic phase removal and it's effect on deformation estimates. The results over the 2001 Bhuj earthquake epicentral region indicate minor deformation rates in the range of ±20 mm year?1. Interpretation of results revealed new subsidence areas between 2014 and 2017.
关键词： time series,surface deformation,bhuj earthquake,TanDEM-X Global DEM,persistent scatterer interferometry
更新于2025-09-23 15:21:21
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Seven Years of Tandem-X: Volume Loss of Grosser Aletschgletscher, Switzerland
摘要： Grosser Aletschgletscher, the largest glacier in the European Alps, contains 20% of the entire Swiss ice mass. However, mass balance simulations based on current climate models predict 90% mass loss by 2100. The glacier is a super-test site for the TanDEM-X satellite mission and data series starting from 2011 are available. In this study we analyzed almost 100 digital elevation models computed from bistatic radar interferograms and compare the derived height loss with model predictions. Additionally, we used patch-based offset tracking to determine a new velocity map of the complete glacier. The results show that the current height loss of 3.3 meters per year is close to that mass balance simulation which uses the ensemble median of common European climate models which predict, relative to 1999, a warming of 4.3?C by 2100.
关键词： offset tracking,radar interferometry,DEM generation,mass balance,Aletsch Glacier,ice velocity
更新于2025-09-23 15:21:21
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LiDAR DEM Data for Flood Mapping and Assessment; Opportunities and Challenges: A Review
摘要： Flooding is the most catastrophic, wide spread, and frequent natural hazards causing extensive damages on infrastructure, human life, and the environment. The frequency and severity of flooding has been increasing all over the world attributed to climate change and escalated urbanization. As such, the issue and techniques of monitoring and mapping flood inundated areas are also increasing. Advancement of state-of-the-art technologies have facilitated and improved flood mapping and monitoring. Earth observation plays important role in flood mapping, monitoring, and damage assessment. However, there are fundamental issues that restricts satellite data from being used for flood studies. LiDAR DEM data based flood modeling approach solves some of the limitations of Earth observation. On the other hand, flood modeling using LiDAR DEM data are challenging. The aim of this review is, therefore, to identify the opportunities and challenges of using LIDAR DEM data for flood mapping and assessment. Substantial literature review was done to attain the stated objective. The study revealed that flood modeling techniques could significantly improve the limitations of detecting flood using Earth observation such as detecting flooded areas under dense canopies and in urban areas. This is attributed to the accurate and fine resolution LiDAR DEM. Furthermore, LiDAR technology provide several opportunities such as relatively cost and time effective data collection system, capability of penetrating dense vegetation, and improved flood model accuracy and fine scale flood modeling. On the other hand, LiDAR data filtering (classification), data availability and accessibility, data file size, high computational time, inability to characterize channels bathymetry, and insufficiency of representing complex urban features are some of the challenges. Therefore, multi-platform LiDAR data (i.e., ground-based, airborne and space borne) and data from additional sources such as echo soundings and electronic theodolite surveys should be integrated to increase the effectiveness of the LiDAR technology for flood modeling.
关键词： Opportunities,Flooding,Flood modeling,Challenges,LiDAR DEM data
更新于2025-09-23 15:21:01
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Multi-physics modelling of molten pool development and track formation in multi-track, multi-layer and multi-material selective laser melting
摘要： Selective laser melting (SLM) is a promising powder-based additive manufacturing technology due to its capability to fabricate metallic components with complex geometries. While most previous investigations focus on printing with a single material, recent industry-orientated studies indicate the need for multi-material SLM in several high-value manufacturing sectors including medical devices, aerospace and automotive industries. However, understanding the underlying physics in multi-material SLM remains challenging due to the di?culties of experimental observation. In this paper, an integrated modelling framework for multi-track, multi-layer and multi-material SLM is developed to advance the in-depth understanding of this process. The main novelty is in modelling the molten pool evolvement and track morphology of multiple materials deposited on the same and across different layers. Discrete element method (DEM) is employed to reproduce the powder deposition process of multiple materials in different deposition patterns, with particle size distribution imported from a particle size analyser. Various phenomena including balling effect, keyhole depression, and lack of fusion between layers are investigated with different laser energy inputs. As a result of the different thermal properties, several process parameters including energy density and hatch spacing are optimised for different powder materials to obtain a continuous track pro?le and improved scanning e?ciency. The interface between two layers of different materials is visualised by simulation; it was found that the phase migration at the interface is related to the convection ?ow inside the molten pool, which contributes to the mixing of the two materials and elemental diffusion. This study signi?cantly contributes to the challenging area of multi-material additive manufacturing by providing a greater in-depth understanding of the SLM process from multi-material powder deposition to laser interaction with powders across multiple scanning tracks and different building layers than can be achieved by experimentation alone.
关键词： Additive manufacturing,Discrete element method (DEM),Computational ?uid dynamics (CFD),Heat transfer,Multi-material,Selective laser melting (SLM)
更新于2025-09-23 15:19:57