scholarly journals Optimizing photogrammetric DEMs for glacier volume change assessment using laser-scanning derived ground-control points

2009 ◽  
Vol 55 (189) ◽  
pp. 106-116 ◽  
Author(s):  
Nicholas E. Barrand ◽  
Tavi Murray ◽  
Timothy D. James ◽  
Stuart L. Barr ◽  
Jon P. Mills
Keyword(s):  
Volume Change ◽  
Laser Scanning ◽  
Airborne Lidar ◽  
Ground Control ◽  
Lidar Data ◽  
Control Points ◽  
Change Models ◽  
Ice Caps ◽  
Ground Control Points ◽  
Stereo Imagery

AbstractPhotogrammetric processing of archival stereo imagery offers the opportunity to reconstruct glacier volume changes for regions where no such data exist, and to better constrain the contribution to sea-level rise from small glaciers and ice caps. The ability to derive digital elevation model (DEM) measurements of glacier volume from photogrammetry relies on good-quality, well-distributed ground reference data, which may be difficult to acquire. This study shows that ground-control points (GCPs) can be identified and extracted from point-cloud airborne lidar data and used to control photogrammetric glacier models. The technique is applied to midtre Lovénbreen, a small valley glacier in northwest Svalbard. We show that the amount of ground control measured and the elevation accuracy of GCP coordinates (based on known and theoretical error considerations) has a significant effect on photogrammetric model statistics, DEM accuracy and the subsequent geodetic measurement of glacier volume change. Models controlled with fewer than 20 lidar control points or GCPs from sub-optimal areas within the swath footprint overestimated volume change by 14–53% over a 2 year period. DEMs derived from models utilizing 20–25 or more GCPs, however, gave volume change estimates within ∼4% of those from repeat lidar data (−0.51 m a−1 between 2003 and 2005). Our results have important implications for the measurement of glacier volume change from archival stereo-imagery sources.

Boresight Calibration of Airborne LiDAR System Without Ground Control Points

2012 ◽  
Vol 9 (1) ◽  
pp. 85-89 ◽  
Author(s):  
Chen Siying ◽  
Ma Hongchao ◽  
Zhang Yinchao ◽  
Zhong Liang ◽  
Xu Jixian ◽  
...  
Keyword(s):  
Airborne Lidar ◽  
Ground Control ◽  
Control Points ◽  
Lidar System ◽  
Ground Control Points

scholarly journals Glacier topography and elevation changes from Pléiades very high resolution stereo images

2014 ◽  
Vol 8 (5) ◽  
pp. 4849-4883 ◽  
Author(s):  
E. Berthier ◽  
C. Vincent ◽  
E. Magnússon ◽  
Á. Þ. Gunnlaugsson ◽  
P. Pitte ◽  
...  
Keyword(s):  
Field Measurements ◽  
Ground Control ◽  
European Alps ◽  
Control Points ◽  
Mass Balances ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Stereo Imagery ◽  
Elevation Changes ◽  
Very High

Abstract. In response to climate change, most glaciers are losing mass and hence contribute to sea-level rise. Repeated and accurate mapping of their surface topography is required to estimate their mass balance and to extrapolate/calibrate sparse field glaciological measurements. In this study we evaluate the potential of Pléiades sub-meter stereo imagery to derive digital elevation models (DEMs) of glaciers and their elevation changes. Our five validation sites are located in Iceland, the European Alps, the Central Andes, Nepal and Antarctica. For all sites, nearly simultaneous field measurements were collected to evaluate the Pléiades DEMs. For Iceland, the Pléiades DEM is also compared to a Lidar DEM. The vertical biases of the Pléiades DEMs are less than 1 m if ground control points (GCPs) are used, but reach up to 6 m without GCPs. Even without GCPs, vertical biases can be reduced to a few decimetres by horizontal and vertical co-registration of the DEMs to reference altimetric data on ice-free terrain. Around these biases, the vertical precision of the Pléiades DEMs is ±1 m and even ±0.5 m on the flat glacier tongues (1-sigma confidence level). We also demonstrate the high potential of Pléiades DEMs for measuring seasonal, annual and multi-annual elevation changes with an accuracy of 1 m or better. The negative glacier-wide mass balances of the Argentière Glacier and Mer de Glace (−1.21 ± 0.16 and −1.19 ± 0.16 m.w.e. yr−1, respectively) are revealed by differencing SPOT5 and Pléiades DEMs acquired in August 2003 and 2012 demonstrating the continuing rapid glacial wastage in the Mont-Blanc area.

Evaluation of 3D Geo-Positioning Based on Bias-Compensated RPCs for Across-Track QuickBird Stereo Imagery

2012 ◽  
Vol 226-228 ◽  
pp. 1958-1964
Author(s):  
Weian Wang ◽  
Shu Ying Xu ◽  
Gang Qiao
Keyword(s):  
Vertical Direction ◽  
Ground Control ◽  
Control Points ◽  
Accuracy Analysis ◽  
Geometric Correction ◽  
Positioning Accuracy ◽  
Ground Control Points ◽  
Order Polynomial ◽  
Stereo Imagery ◽  
Very High

This paper investigates the geo-positioning accuracy of across-track QuickBird stereo imagery in Shanghai, China, where the terrain relief is very low about 3m but with very high buildings up to 380m. The rational function model (RFM) and the bias-compensated RFM with different parameters are employed to do accuracy analysis with different configurations of ground control points (GCPs). The systematic errors in vendor provided RPCs are revealed and discussed. The results of bias-compensated RFM show that different strategies in terms of the number of GCP and different geometric correction methods should be taken into consideration in order for a better and reasonable positioning accuracy in the three directions. The results also show that the best accuracy of 0.6m in horizontal direction and 0.8m in vertical direction can be acquired by the second-order polynomial model when GCPs are more than 8.

scholarly journals Glacier topography and elevation changes derived from Pléiades sub-meter stereo images

2014 ◽  
Vol 8 (6) ◽  
pp. 2275-2291 ◽  
Author(s):  
E. Berthier ◽  
C. Vincent ◽  
E. Magnússon ◽  
Á. Þ. Gunnlaugsson ◽  
P. Pitte ◽  
...  
Keyword(s):  
Field Measurements ◽  
Ground Control ◽  
European Alps ◽  
Control Points ◽  
Mass Balances ◽  
Ground Control Points ◽  
Digital Elevation ◽  
Stereo Imagery ◽  
Elevation Changes ◽  
Spot 5

Abstract. In response to climate change, most glaciers are losing mass and hence contribute to sea-level rise. Repeated and accurate mapping of their surface topography is required to estimate their mass balance and to extrapolate/calibrate sparse field glaciological measurements. In this study we evaluate the potential of sub-meter stereo imagery from the recently launched Pléiades satellites to derive digital elevation models (DEMs) of glaciers and their elevation changes. Our five evaluation sites, where nearly simultaneous field measurements were collected, are located in Iceland, the European Alps, the central Andes, Nepal and Antarctica. For Iceland, the Pléiades DEM is also compared to a lidar DEM. The vertical biases of the Pléiades DEMs are less than 1 m if ground control points (GCPs) are used, but reach up to 7 m without GCPs. Even without GCPs, vertical biases can be reduced to a few decimetres by horizontal and vertical co-registration of the DEMs to reference altimetric data on ice-free terrain. Around these biases, the vertical precision of the Pléiades DEMs is ±1 m and even ±0.5 m on the flat glacier tongues (1σ confidence level). Similar precision levels are obtained in the accumulation areas of glaciers and in Antarctica. We also demonstrate the high potential of Pléiades DEMs for measuring seasonal, annual and multi-annual elevation changes with an accuracy of 1 m or better if cloud-free images are available. The negative region-wide mass balances of glaciers in the Mont-Blanc area (−1.04 ± 0.23 m a−1 water equivalent, w.e.) are revealed by differencing Satellite pour l'Observation de la Terre 5 (SPOT 5) and Pléiades DEMs acquired in August 2003 and 2012, confirming the accelerated glacial wastage in the European Alps.

scholarly journals A LIGHT-WEIGHT LASER SCANNER FOR UAV APPLICATIONS

2016 ◽  
Vol XLI-B1 ◽  
pp. 711-715 ◽  
Author(s):  
A. M. G. Tommaselli ◽  
F. M. Torres
Keyword(s):  
Laser Scanning ◽  
Cost Benefit ◽  
Ground Control ◽  
Raspberry Pi ◽  
Weight System ◽  
Scanning System ◽  
Light Weight ◽  
Control Points ◽  
Ground Control Points ◽  
Flight Height

Unmanned Aerial Vehicles (UAV) have been recognized as a tool for geospatial data acquisition due to their flexibility and favourable cost benefit ratio. The practical use of laser scanning devices on-board UAVs is also developing with new experimental and commercial systems. This paper describes a light-weight laser scanning system composed of an IbeoLux scanner, an Inertial Navigation System Span-IGM-S1, from Novatel, a Raspberry PI portable computer, which records data from both systems and an octopter UAV. The performance of this light-weight system was assessed both for accuracy and with respect to point density, using Ground Control Points (GCP) as reference. Two flights were performed with the UAV octopter carrying the equipment. In the first trial, the flight height was 100 m with six strips over a parking area. The second trial was carried out over an urban park with some buildings and artificial targets serving as reference Ground Control Points. In this experiment a flight height of 70 m was chosen to improve target response. Accuracy was assessed based on control points the coordinates of which were measured in the field. Results showed that vertical accuracy with this prototype is around 30 cm, which is acceptable for forest applications but this accuracy can be improved using further refinements in direct georeferencing and in the system calibration.

Highway Cross-Slope Measurement using Mobile LiDAR

2018 ◽  
Vol 2672 (39) ◽  
pp. 88-97 ◽  
Author(s):  
Alireza Shams ◽  
Wayne A. Sarasua ◽  
Afshin Famili ◽  
William J. Davis ◽  
Jennifer H. Ogle ◽  
...  
Keyword(s):  
South Carolina ◽  
Laser Scanning ◽  
Effective Means ◽  
Cost Effective ◽  
Measurement Unit ◽  
Ground Control ◽  
Lidar Data ◽  
Ground Control Points ◽  
South Carolina Department ◽  
The Difference

Ensuring adequate pavement cross-slope on highways can improve driver safety by reducing the potential for ponding to occur or vehicles to hydroplane. Mobile laser scanning (MLS) systems provide a rapid, continuous, and cost-effective means of collecting accurate 3D coordinate data along a corridor in the form of a point cloud. This study provides an evaluation of MLS systems in terms of the accuracy and precision of collected cross-slope data and documentation of procedures needed to calibrate, collect, and process this data. Mobile light detection and ranging (LiDAR) data were collected by five different vendors on three roadway sections. The results indicate the difference between ground control adjusted and unadjusted LiDAR derived cross-slopes, and field surveying measurements less than 0.19% at a 95% confidence level. The unadjusted LiDAR data incorporated corrections from an integrated inertial measurement unit and high-accuracy real-time kinematic GPS, however it was not post-processed adjusted with ground control points. This level of accuracy meets suggested cross-slope accuracies for mobile measurements (±0.2%) and demonstrates that mobile LiDAR is a reliable method for cross-slope verification. Performing cross-slope verification can ensure existing pavement meets minimum cross-slope requirements, and conversely is useful in identifying roadway sections that do not meet minimum standards, which is more desirable than through crash reconnaissance where hydroplaning was evident. Adoption of MLS would enable the South Carolina Department of Transportation (SCDOT) to address cross-slope issues through efficient and accurate data collection methods.

scholarly journals Potential of RADARSAT-2 stereo radargrammetry for the generation of glacier DEMs

2016 ◽  
Vol 62 (233) ◽  
pp. 486-496 ◽  
Author(s):  
C. PAPASODORO ◽  
A. ROYER ◽  
A. LANGLOIS ◽  
E. BERTHIER
Keyword(s):  
Remote Sensing ◽  
Mass Loss ◽  
Mass Balance ◽  
Confidence Level ◽  
Ground Control ◽  
Control Points ◽  
Ice Caps ◽  
Ice Cap ◽  
Ground Control Points ◽  
Elevation Changes

ABSTRACTThe study of glaciers and ice caps in remote and cloudy regions remains difficult using current remote sensing tools. Here the potential of stereo radargrammetry (SRG) with RADARSAT-2 Wide Ultra-Fine images is explored for DEM extraction, elevation changes and mass-balance calculations on Barnes Ice Cap (Nunavut, Canada). Over low-relief terrain surrounding Barnes, a vertical precision of ~7 m (1σ confidence level) is measured, as well as an average vertical bias of ~4 m. Moreover, we show that the C-band penetration depth over the ice cap is insignificant at this time of the year (i.e. late ablation season). This is likely due to a wet surface and the presence of superimposed ice that leads to a surface radar response. Comparing the SRG DEMs with other datasets, an historical glacier-wide mass balance of −0.52 ± 0.19 m w.e. a−1is estimated for 1960–2013, whereas it decreases to −1.06 ± 0.84 m w.e. a−1between 2005 and 2013. This clear acceleration of mass loss is in agreement with other recent studies. Given its all-weather functionality and its possible use without ground control points, the RADARSAT-2 SRG technology represents an appropriate alternative for glacier monitoring in cloudy and remote regions.

scholarly journals Corridor Mapping of Sandy Coastal Foredunes with UAS Photogrammetry and Mobile Laser Scanning

2019 ◽  
Vol 11 (11) ◽  
pp. 1352 ◽  
Author(s):  
Alphonse Nahon ◽  
Pere Molina ◽  
Marta Blázquez ◽  
Jennifer Simeon ◽  
Sylvain Capo ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Management Practices ◽  
Control Point ◽  
Unmanned Aircraft ◽  
Ground Control ◽  
Scanning System ◽  
Control Points ◽  
Ground Control Points ◽  
Spatial Coverage ◽  
Mean Square Errors

Recurrent monitoring of sandy beaches and of the dunes behind them is needed to improve the scientific knowledge on their dynamics as well as to develop sustainable management practices of those valuable landforms. Unmanned Aircraft Systems (UAS) are sought as a means to fulfill this need, especially leveraged by photogrammetric and LiDAR-based mapping methods and technology. The present study compares different strategies to carry UAS photogrammetric corridor mapping over linear extensions of sandy shores. In particular, we present results on the coupling of a UAS with a mobile laser scanning system, operating simultaneously in Cap Ferret, SW France. This aerial-terrestrial tandem enables terrain reconstruction with kinematic ground control points, thus largely avoiding the deployment of surveyed ground control points on the non-stable sandy ground. Results show how these three techniques—mobile laser scanning, photogrammetry based on ground control points, and photogrammetry based on kinematic ground control points—deliver accurate (i.e., root mean square errors < 15 cm) 3D reconstruction of beach-to-dune transition areas, the latter being performed at lower survey and logistic costs, and with enhanced spatial coverage capabilities. This study opens the gate for exploring longer (hundreds of kilometers) shoreline dynamics with ground-control-point-free air and ground mapping techniques.

COMPARATIVE ANALYSIS OF ASTER DEM, ASTER GDEM, AND SRTM DEM BASED ON GROUND-TRUTH GPS DATA

2015 ◽  
Vol 76 (1) ◽  
Author(s):  
Komeil Rokni ◽  
Anuar Ahmad ◽  
Sharifeh Hazini
Keyword(s):  
Ground Truth ◽  
Ground Control ◽  
Control Points ◽  
Pixel Size ◽  
Dual Frequency ◽  
Srtm Dem ◽  
Aster Gdem ◽  
Ground Control Points ◽  
Stereo Imagery ◽  
Aster Image

This study aims to compare the accuracies of ASTER DEM, ASTER GDEM, and SRTM DEM for the area of Universiti Teknologi Malaysia (UTM) and surrounding. In doing so, a number of Ground Control Points (GCPs) were collected using GPS technology and used to generate an absolute DEM using the ASTER stereo imagery. Moreover, two well-known DEMs including ASTER GDEM and SRTM DEM were obtained for the same area with ASTER image. Subsequently, several high accuracy ground-truth points were established around UTM using dual frequency GPS and used to assess the accuracies of the obtained DEMs. The results indicate that an elevation Root Mean Square Error (RMSE) of ±14.86m is achieved for the generated ASTER DEM, which is less than the 15m pixel size of ASTER image. The results further show that the elevation RMSEs of the ASTER GDEM and SRTM DEM are respectively ±4.52m and ±4.14m for the study area. The results illustrate although the resolution of SRTM DEM is much lower than ASTER GDEM, it could provide higher elevation accuracy. Finally, although the accuracy of the ASTER DEM in this study is not high in comparison with the accuracies of ASTER GDEM and SRTM DEM, based on the selected number of check points and resolution of ASTER image, it could be useful for various geoinformation applications.

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