J. L. Pérez-García

Accuracy of contour lines using 3D bands

This article describes a new methodology for the planimetric control of contour lines. The method is based on the generation of buffers around the contour lines which define a 3D buffer around the maximum slope line. After that we analyze the quantity of points from a more accurate source which is inside this buffer. As a result, we obtain a distribution function of the control points included when we apply several widths to the buffers. We have also determined the angularity and height differences of these points. The method has been applied to several sets of contour line intervals derived from a digital elevation model (DEM) and to the contour lines of one published topographic map using the DEM as the control source. We have also analyzed the representative behaviour of the contour lines, taking into account the contour line interval and the detection of an uncertainty model based on the slope variation. This study demonstrates the viability of the proposed method for obtaining the uncertainty of the contour lines depending on a given level of confidence and the variability of this uncertainty in the map. Finally, we propose a range of contour line intervals based on the scale and slopes.

Monitoring of landslide displacements using UAS and control methods based on lines

This study describes a new methodology for monitoring landslide displacements using a set of linear elements included in the terrain. These linear elements are digitized using the products obtained from several photogrammetric flights implemented by means of unmanned aircraft systems in several dates. The control of the displacements between dates is carried out using some new metrics and methods based on lines. The results of the control of the lines are used to analyse the general and particular behaviour of the landslide. Using this type of elements allows us to study some singular behaviour of linear elements included in the landslides (e.g. an affected road can react as a block). The methodology has been tested with success using a real case of an active slope with several landslides which was studied on three separate dates. The results have demonstrated the viability of using this methodology for studying the evolution of the landslides and their consequences regarding certain elements included in the terrain.

Web-Based System for the Self-Evaluation of the Calculations of Students Applied to Education in Surveying Engineering and Photogrammetry

In this paper, a Web-based system oriented toward students of surveying engineering and photogrammetry is presented. This application allows student self-evaluation of the calculations and problems involved in practical work. Students can evaluate their calculations before the final evaluation, minimizing the usual mistakes, primarily those of calculation errors. The evaluation of this system is based on the numbers and types of access to the system; the results of a satisfaction survey; and, primarily, a test of the proposed learning methodology. These results have demonstrated the viability of the tool developed in this project with regard to achieving the main objective, which consists of the students’ self-evaluation of their calculations and assimilation of the causes of their mistakes. The system is therefore shown to reinforce and stimulate autonomous learning.