Towards accurate determination of surface height using modern geoinformatic methods: possibilities and limitations

Abstract

Over recent decades several modern geoinformatic height-finding methods have emerged, including global positioning system (GPS), interferometric radar, and airborne laser scanner (ALS) or lidar. In conjunction with the conventional survey and photogrammetric method, they have found wide applications that demand varying levels of accuracy. In this paper, the principles of each method are briefly summarized. The discussion then concentrates on the accuracy level achievable with each method. The factors that affect the accuracy, wherever possible, are comprehensively evaluated. This review has revealed that the highest accuracy achievable is still with the levelling method, followed by the photogrammetric method. This situation is likely to change in light of real-time kinematic GPS coupled with ALS. In contrast to the imaging methods that are suited to obtain highly accurate, fine-resolution digital elevation models (DEMs) at a local scale, GPS is the most efficient at obtaining heights at spots or along lines accurately. ALS is the only method applicable to acquisition of subsurface heights in vegetated areas. These airborne methods are complementary to their space-borne counterparts, such as Shuttle Radar Topographic Mapping and Shuttle Laser Altimeter, both being ideal in obtaining DEMs at the regional and global scales. The synergistic use of GPS with lidar offers the best hope in obtaining cm-level accuracies essential for monitoring ground subsidence and tectonic uplift. Height measurements accurate to subcentimetres needed for national levelling surveys are possible only after the tropospheric path delay is externally calibrated using Raman lidar data during GPS data analysis.

Deciphering the Precision of Stereo IKONOS Canopy Height Models for US Forests with G-LiHT Airborne LiDAR

“…We believe this provided an unbiased and quantitative way to identify errors that may propagate into IKONOS CHMs. The precision of LiDAR measurements ranging is submeter but due to limitations in geolocating points and sampling density G-LiHT CHM accuracy is degraded to ~1 m [6]. We believe comparing DTM and DSM stereo results to G-LiHT is best approach to evaluate the accuracy of these products.…”

“…Many remote sensing approaches exist to document the structural state of forests. RAdio Detection And Ranging (RADAR), Light Detection And Ranging (LiDAR), and photogrammetric methods using stereo imagery, have all been used to measure forest structure and each approach has varying accuracies and implementation costs [4,6]. We evaluated two existing stereo forest canopy height model (CHM) approaches, one without ground control points (GCPs) and one with GCPs as others have shown substantial improvement in IKONOS mapping accuracy with GCPs [7,8].…”

“…Often best results have been found relating field measurements to small footprint LiDAR, and HSRI has been found to be the second best option [6]. From prior successful outputs of these studies in urban environments and a handful of forest canopy studies [5,10,32], we performed an assessment of the capabilities of existing remote sensing data to map canopy heights in three different biogeographic forested regions of the CONUS including Appalachian, Atlantic Coastal Plain, and North American Pacific Maritime.…”

Countrywide Stereo-Image Matching for Updating Digital Surface Models in the Framework of the Swiss National Forest Inventory

“…Three-dimensional data can either be acquired with an active laser or radar system, or passively with a camera taking optical images [9]. In forested areas, airborne laser scanning (ALS) is often the method of choice, because ALS can penetrate the forest canopy and is, therefore, the only means of obtaining sub-canopy forest structure and terrain information [10].…”

Surface changes on a landslide affected high bluff in Dunaszekcső (Hungary)

“…Such seasonal variability was also found in former studies [34] that investigated surface change over a long time period. However, the accuracy of the measuring methods can be debated [35,36], which is why rounded values and the pattern of change were analysed in this study. The maximum vertical displacement is detected on the Eastern part of the study area, and was caused by bank instability after last major movement in 2008.…”