J. Martínez-Sánchez

3D Modeling of Building Indoor Spaces and Closed Doors from Imagery and Point Clouds

3D models of indoor environments are increasingly gaining importance due to the wide range of applications to which they can be subjected: from redesign and visualization to monitoring and simulation. These models usually exist only for newly constructed buildings; therefore, the development of automatic approaches for reconstructing 3D indoors from imagery and/or point clouds can make the process easier, faster and cheaper. Among the constructive elements defining a building interior, doors are very common elements and their detection can be very useful either for knowing the environment structure, to perform an efficient navigation or to plan appropriate evacuation routes. The fact that doors are topologically connected to walls by being coplanar, together with the unavoidable presence of clutter and occlusions indoors, increases the inherent complexity of the automation of the recognition process. In this work, we present a pipeline of techniques used for the reconstruction and interpretation of building interiors based on point clouds and images. The methodology analyses the visibility problem of indoor environments and goes in depth with door candidate detection. The presented approach is tested in real data sets showing its potential with a high door detection rate and applicability for robust and efficient envelope reconstruction.

Semiautomatic Extraction of Road Horizontal Alignment from a Mobile LiDAR System

This article proposes a method to semiautomatically extract the road axis through a mobile LiDAR system, a recent popular technology for transportation-related applications, road estimation and even to enhance driver safety. In particular, the approach developed has two components: (1) the feature extraction from LiDAR data to model the road axis, and (2) the estimation of the horizontal alignment that meets the requirements and practice for a transportation authority. Given the massive and complex character of the data captured by the system, a hierarchical (coarse-to-fine) and robust strategy based on segmentation, parameterization and filtering, which determine the road centerline together with the geometric elements that compose its horizontal alignment, such as straight lines, circular arcs, and clothoids, has been developed and implemented. Test results using a simulated and a real data are discussed and validated. The experimental results obtained with real cases guarantying relative accuracies under 2%, being a useful approach to produce accurate estimations of the horizontal geometric features of the road alignment.

Successful Applications of Geotechnologies for the Evaluation of Road Infrastructures

This work reports the results obtained over several years of research into the application of different geomatic techniques in the field of civil engineering and, in particular, in their application to the management of road systems and associated structures. Among the main advances obtained are the quantification of parameters during the inventorying and inspection of infrastructures, the metric quality of the results and the development of hardware and software tools for the automation of road systems management.

GPR for road inspection: Georeferencing and efficient approach to data processing and visualization

GPR is a recommendable non-destructive technique for thickness measurement of pavement layers because data acquisition takes place at normal traffic speeds, making GPR a cost-effective technique. On the other hand, the large collected data, when the GPR system is mounted on a moving vehicle, is difficult to process. Given that processing is conducted by qualified practitioners, it is a key to obtain software tools that allow for accurate thickness measurements and fast processing times. In this paper, an easy to use and intuitive tool for pavement thickness measurement is presented. Exploiting the power of C++ programming language and the Qt framework advantages for developing applications with graphic interface, a simple and intuitive tool for a qualified worker is implemented in order to reduce the processing times and to give information at the earliest possible moment. Furthermore, the software provides a visualization application for the georeferencing of the field GPR data by using additional GPS (Global Positioning System) data. Given that the GPR acquisition software can connect to an external GPS for trace tagging, NMEA synchronization was used in this case. If the connection is set properly, the GPR acquisition software creates a number of files in order to get the GPR traces paired with a GGA sentence. After post-processing, all the traces are referenced to a SBET (Smooth Best Estimated Trajectory).

Novel Aerial 3D Mapping System Based on UAV Platforms and 2D Laser Scanners

The acquisition of 3D geometric data from an aerial view implies a high number of advantages with respect to terrestrial acquisition, the greatest being that aerial view allows the acquisition of information from areas with no or difficult accessibility, such as roofs and tops of trees. If the aerial platform is copter-type, other advantages are present, such as the capability of displacement at very low-speed, allowing for a more detailed acquisition. This paper presents a novel Aerial 3D Mapping System based on a copter-type platform, where a 2D laser scanner is integrated with a GNSS sensor and an IMU for the generation of georeferenced 3D point clouds. The accuracy and precision of the system are evaluated through the measurement of geometries in the point clouds generated by the system, as well as through the geolocation of target points for which the real global coordinates are known.

Quantitative Evaluation of CHT and GHT for Column Detection under Different Conditions of Data Quality

AbstractQuality control and project monitoring are topics of interest in the field of architectural-engineering-construction/facility management. The need to automatise the process and analyze data...

Applications of GPR in Association with Other Non-destructive Testing Methods in Surveying of Transport Infrastructures

Preservation and maintenance of transport infrastructure is a global concern that affects social and economic development in all countries. During the last decades, there has been a continuous increase in the use of non-destructive testing (NDT) applied to many aspects related to civil engineering field. Ground Penetrating Radar (GPR) has become an established method of inspection. This paper presents a compilation of works in the frame of the applications of GPR and other NDT methods in the evaluation of transport infrastructures. Published works in roads and pavements, concrete and masonry structures, and tunnel testing are mentioned. It has been demonstrated that such methods have significantly benefited the procedures for inspection and also, successfully solved some of the limitations of traditional methods.

3D reconstruction of cubic armoured rubble mound breakwaters from incomplete lidar data

This manuscript proposes an algorithm for the reconstruction of the cube armoured rubble mound breakwaters’ geometry from incomplete lidar point clouds in order to perform structural monitoring over time. Rubble mound breakwaters are critical structures used in the protection of beaches and ports. The constant wave actions result in the degradation of these defences, causing catastrophic coastal damage. Early detection of the degradation of the breakwaters is a key topic to prevent disasters. Remote-sensing techniques such as lidar and photogrammetry contribute to the monitoring of civil engineering structures. The reconstruction of cube armoured breakwaters relies on normal-vector segmentation and a priori cube’s properties. For the successful modelling of the armour units, two options are available, the first one requires three perpendicular planes of the cube to be scanned and segmented, while for the second, only two planes are required. The resulting models were compared to ground truth handmade delineation of 1.25 m side length cubed armour units, leading to an accuracy range of 7–15 cm. Besides that, the precision results are constrained to 2.7–9.9 mm for the three plane-based reconstruction and 7.2–14.5 mm for the two plane-based one. The reconstructed armour units are well defined and suitable to be used as a 3D computer-aided design (CAD) model for monitoring breakwaters.

Segmentation of Indoor Mapping Point Clouds Applied to Crime Scenes Reconstruction

Data acquisition in forensics science must be performed in a fast and an efficient way, so that the data acquired is maximized at the same time that disturbance and time on the scene are minimized. For this reason, the use of indoor mapping systems appears as a key solution, in contrast with static systems, either laser or photogrammetry based, in which representing big and complex scenes requires acquisition from a high number of positions, and long-time dedication for data processing. This paper presents a methodology for the segmentation of point clouds acquired with a mobile indoor mapping system, and their conversion to 3-D models in CAD format, based on parameterized geometric elements from the scene. This way, all the information required in forensic sciences is stored in an adequate digital format, enabling its availability in the future, and minimizing time dedication in both data acquisition and processing steps.

Automatic Measurement of Water Height in the As Conchas (Spain) Reservoir Using Sentinel 2 and Aerial LiDAR Data

A methodology for the measurement of height in water reservoirs is developed. It is based on Sentinel 2 imagery and aerial LiDAR data. The methodology is automatized using Matlab software and focused on image processing techniques (equalization, binarization, and edge detection) combined with LiDAR data processing (near neighbour search and height averaging). It is applied in a region of interest selected by the user characterized by a water–land interface. Results are validated in the As Conchas water reservoir (Spain) using an in situ sensing system provided by the Hydrographic Mino-Sil Confederation. The duration of the experiment was one year. The Sentinel 2 bands B2, B3, B4, and B8 were tested during this study. The best results for water height evaluation were obtained for band B8 (842 nm) with an error of 0.20 m and a standard deviation of 0.17 m. The time resolution of the technique depends on the Sentinel 2 revisit time. The time resolution and height accuracy could be improved using complementary satellite systems.