Measurement of Road Surface Deformation Using Images Captured from UAVs

Abstract

This paper presents a methodology for measuring road surface deformation due to terrain instability processes. The methodology is based on ultra-high resolution images acquired from unmanned aerial vehicles (UAVs). Flights are georeferenced by means of Structure from Motion (SfM) techniques. Dense point clouds, obtained using the multiple-view stereo (MVS) approach, are used to generate digital surface models (DSM) and high resolution orthophotographs (0.02 m GSD). The methodology has been applied to an unstable area located in La Guardia (Jaen, Southern Spain), where an active landslide was identified. This landslide affected some roads and accesses to a highway at the landslide foot. The detailed road deformation was monitored between 2012 and 2015 by means of eleven UAV flights of ultrahigh resolution covering an area of about 260 m × 90 m. The accuracy of the analysis has been established in 0.02 ± 0.01 m in XY and 0.04 ± 0.02 m in Z. Large deformations in the order of two meters were registered in the total period analyzed that resulted in maximum average rates of 0.62 m/month in the unstable area. Some boundary conditions were considered because of the low required flying height (<50 m above ground level) in order to achieve a suitable image GSD, the fast landslide dynamic, continuous maintenance works on the affected roads and dramatic seasonal vegetation changes throughout the monitoring period. Finally, we have analyzed the relation of displacements to rainfalls in the area, finding a significant correlation between the two variables, as well as two different reactivation episodes.

Multitemporal Analysis of Gully Erosion in Olive Groves by Means of Digital Elevation Models Obtained with Aerial Photogrammetric and LiDAR Data

“…Thus, the maximum values of precipitation in 24 h and the mean annual rainfalls which occurred in 1997 and 2010 generated an increase of the drainage network. These patterns and relationships have been observed in other processes such as landslides in the region [57,70] under an irregular rainfall regime in which dry periods of several years alternate with wet periods concentrated throughout the autumn-winter seasons of two or three consecutive years. Nevertheless, as can be observed in Figure 9 and Tables 6 and 7, the rainfalls related to the period 1996-2001 are approximately 80% of the rainfalls of the period 2009-2011, but their consequences in the erosion processes are about 50%.…”

“…First, a quality control of the LiDAR points cloud was carried out with some field GNSS surveyed points. This control showed that horizontal (XY) mean and RMS errors were around 0.7 m, while the vertical (Z) mean error was of 0.24 m in absolute value, and the RMS and SD errors were about 0.40-0.45 m. From these errors, the uncertainties, estimated as the values of RMS or SD as in previous studies [57,58,70], were of 0.7 m for the horizontal component and 0.5 m for the vertical one. Then the horizontal uncertainty for X and Y would be about 0.5 m for each one, which coincides approximately with half of the LiDAR data resolution and is equal to the orthophotographs resolution.…”

“…The methodology summarized in Figure 3 consists of several phases partially described in previous papers [57,58,70]:…”

“…In this paper as in previous ones [57,58,70], DSMs have been used preferably to DTMs. This is because all the models used for computing DoDs are of photogrammetric origin, and thus, the processes of automatic classification and filtering of point clouds do not ensure good results in areas where there is a certain vegetation cover or other elements.…”

Using Small Unmanned Aerial Vehicle in 3D Modeling of Highways with Tree-Covered Roadsides to Estimate Sight Distance

“…UAV-based digital imaging systems are capable of collecting surface condition data to characterize unpaved roads [5,6]. UAV platforms have also been used to measure road surface deformation with high accuracy [7]. Feng et al [8] extracted highway geometry features from a UAV mapping system.…”