An evaluation of the effectiveness of low-cost UAVs and structure from motion for geomorphic change detection

Cook, Kristen

doi:10.1016/j.geomorph.2016.11.009

Cited by 318 publications

(295 citation statements)

References 44 publications

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“…These results agree with other studies that have used aerial platforms to capture images across large areas in complex terrain (RMSE values ranging from 0.05 m to~1 m [18,36,47,[101][102][103]), and ground-based approaches to model gully systems (RMSE values ranging from 0.025 m to 0.155 m [40][41][42]46,47,49,104,105]). While the overall elevation errors of the UAV topographic models were large relative to a pre-existing airborne LiDAR dataset and RTK validation points, cross-sections extracted from the UAV DSM broadly match the shape of gully profiles, although are vertically offset.…”

Section: Resolution and Accuracysupporting

confidence: 90%

“…In the point-to-point comparison, elevation values were extracted from the dense point cloud (prior to rasterization) and compared to concordant RTK validation points, using the 'compute cloud/cloud distance' tool in CloudCompare. Point-to-point comparison is useful in topographically complex environments [101] such as gullies, where steep sides and overhangs are common [46], as a given set of x and y coordinates can have multiple z values [42,102]. In the raster-to-raster comparison, the UAV DSM was subtracted from the airborne LiDAR DEM, allowing examination of the spatial distribution of error.…”

Section: Elevation Accuracy Of Sfm-mvs Topographic Modelsmentioning

confidence: 99%

“…Vegetation is particularly problematic for SfM-MVS in tropical savannas, which are characterised by a grassy understory of variable density and structure and a discontinuous layer of trees and shrubs. Vegetation obstructs the view of the ground, is prone to movement (key-point matching algorithms rely on a static scene), and has a complex structure that is difficult to reconstruct [13,101,102]. Examination of the error model between the airborne LiDAR DEM and UAV DSM clearly identify higher errors in areas corresponding to the position of dense vegetation patches (such as tree canopies and bushes).…”

Section: Vegetationmentioning

confidence: 99%

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Assessment of UAV and Ground-Based Structure from Motion with Multi-View Stereo Photogrammetry in a Gullied Savanna Catchment

Koci

Jarihani

Leon

et al. 2017

IJGI

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Abstract:Structure from Motion with Multi-View Stereo photogrammetry (SfM-MVS) is increasingly used in geoscience investigations, but has not been thoroughly tested in gullied savanna systems. The aim of this study was to test the accuracy of topographic models derived from aerial (via Unmanned Aerial Vehicle, 'UAV') and ground-based (via handheld digital camera, 'ground') SfM-MVS in modelling hillslope gully systems in a dry-tropical savanna, and to assess the strengths and limitations of the approach at a hillslope scale and an individual gully scale. UAV surveys covered three separate hillslope gully systems (with areas of 0.412-0.715 km 2 ), while ground surveys assessed individual gullies within the broader systems (with areas of 350-750 m 2 ). SfM-MVS topographic models, including Digital Surface Models (DSM) and dense point clouds, were compared against RTK-GPS point data and a pre-existing airborne LiDAR Digital Elevation Model (DEM). Results indicate that UAV SfM-MVS can deliver topographic models with a resolution and accuracy suitable to define gully systems at a hillslope scale (e.g., approximately 0.1 m resolution with 0.4-1.2 m elevation error), while ground-based SfM-MVS is more capable of quantifying gully morphology (e.g., approximately 0.01 m resolution with 0.04-0.1 m elevation error). Despite difficulties in reconstructing vegetated surfaces, uncertainty as to optimal survey and processing designs, and high computational demands, this study has demonstrated great potential for SfM-MVS to be used as a cost-effective tool to aid in the mapping, modelling and management of hillslope gully systems at different scales, in savanna landscapes and elsewhere.

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Section: Resolution and Accuracysupporting

confidence: 90%

Section: Elevation Accuracy Of Sfm-mvs Topographic Modelsmentioning

confidence: 99%

Section: Vegetationmentioning

confidence: 99%

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Assessment of UAV and Ground-Based Structure from Motion with Multi-View Stereo Photogrammetry in a Gullied Savanna Catchment

Koci

Jarihani

Leon

et al. 2017

IJGI

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Section: Us Environmental Protection Agencymentioning

confidence: 99%

“…Although the powerful SfM method has been applied to a wide range of geoscience research, such as gully water erosion, ice surface research, and landform evolution (Cook 2017;James and Robson 2012;Nouwakpo et al 2016;Prosdocimi et al 2017;Smith et al 2016;Stöcker et al 2015), this is the first time it is used in the wind erosion field to our knowledge. Neither the numerical simulations in the previous section nor the field measurements in this section could consider a wide range of pile parameters, and we want to check if the proposed factor can reflect the general trend of the influence of pile heights on wind erosion instead of specific erosion values.…”

Section: Us Environmental Protection Agencymentioning

confidence: 99%

Amplification factors to estimate wind erosion of piles of soil with different heights: Numerical simulation and structure-from-motion photogrammetry verification

Liu¹,

Qu²,

Ning³

2018

Journal of Soil and Water Conservation

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Abstract:In this study, we propose amplification factors of single conical piles with different heights and sizes to describe wind erosion acceleration effects of piles compared to flat erodible surfaces. It is not difficult using traditional wind erosion models to estimate wind erosion of flat agricultural land or pastoral surfaces. However, in the current form these models cannot be used for elevated surfaces such as dunes or piles, which may lead to more serious dust emission and air pollution. A computational fluid dynamics simulation was used to refine a wind erosion estimation method of pile from the US Environmental Protection Agency (USEPA) by dividing the pile surface into multiple subareas with constant wind speed for each subarea and then obtaining ratios of pile erosion to the corresponding flat surface by calculating the total erosion rate of the pile and that of a flat surface with the same floor area. The ratios as amplification factors, E amp , for six pile sizes (from 1 to 12 m) and five wind speed scenarios covering most erosive daily wind speeds from 824 stations throughout China were analyzed and fitted to equations to enable consideration of other heights and wind speed conditions. The changing patterns of the factors were verified using experimental surveys of two plots via the structure-from-motion photogrammetry method, which generated high-resolution digital elevation maps and detected detailed erosion changes. The erosion from a stockpile surface was found to be 2.52 to 7.16 times that from a flat surface with the same floor area, and the influence of pile height on amplification factor could be expressed by a logarithmic equation. These factors can be easily applied to estimate pile erosion by multiplying them by wind erosion results for flat surfaces obtained from other indexes or models. The procedure described in this paper can be extended to consider amplification or reduction effects of dunes, hills, piles, pits, and gullies with different shapes or configurations in relation to wind erosion. Furthermore, the reliability of wind erosion estimation over complex surfaces can be improved to implement specific soil conservation practices.Key words: computational fluid dynamics-Dunhuang-pile-structure-from-motion photogrammetry-wind erosion Wind erosion produces suspended particles from erodible surfaces and causes air pollution, land degradation, and human health problems. The impact of wind erosion is significant in areas severely affected by poor air quality, such as northern China. The effects of terrain obstructions like dunes or piles on modifying wind speed and wind erosion have long been identified (Bagnold 1941; Stunder and Arya 1988;Sullivan and Ajwa 2011). Several models have been developed and improved to estimate wind erosion from agricultural, pastoral, and, sometimes, human disturbed surfaces (Alfaro and Gomes 2001;Hagen 2001;Tatarko et al. 2016;Wagner 2013;Zhang et al. 2017). However, there are no models capable of estimating wind erosion from elevated surfaces because ...

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Advances in understanding river‐groundwater interactions

Brunner

Therrien

Renard

et al. 2017

Reviews of Geophysics

191

126

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River‐groundwater interactions are at the core of a wide range of major contemporary challenges, including the provision of high‐quality drinking water in sufficient quantities, the loss of biodiversity in river ecosystems, or the management of environmental flow regimes. This paper reviews state of the art approaches in characterizing and modeling river and groundwater interactions. Our review covers a wide range of approaches, including remote sensing to characterize the streambed, emerging methods to measure exchange fluxes between rivers and groundwater, and developments in several disciplines relevant to the river‐groundwater interface. We discuss approaches for automated calibration, and real‐time modeling, which improve the simulation and understanding of river‐groundwater interactions. Although the integration of these various approaches and disciplines is advancing, major research gaps remain to be filled to allow more complete and quantitative integration across disciplines. New possibilities for generating realistic distributions of streambed properties, in combination with more data and novel data types, have great potential to improve our understanding and predictive capabilities for river‐groundwater systems, especially in combination with the integrated simulation of the river and groundwater flow as well as calibration methods. Understanding the implications of different data types and resolution, the development of highly instrumented field sites, ongoing model development, and the ultimate integration of models and data are important future research areas. These developments are required to expand our current understanding to do justice to the complexity of natural systems.

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An evaluation of the effectiveness of low-cost UAVs and structure from motion for geomorphic change detection

Cited by 318 publications

References 44 publications

Assessment of UAV and Ground-Based Structure from Motion with Multi-View Stereo Photogrammetry in a Gullied Savanna Catchment

Assessment of UAV and Ground-Based Structure from Motion with Multi-View Stereo Photogrammetry in a Gullied Savanna Catchment

Amplification factors to estimate wind erosion of piles of soil with different heights: Numerical simulation and structure-from-motion photogrammetry verification

Advances in understanding river‐groundwater interactions

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