Photogrammetry for digital reconstruction of railway ballast particles – A cost-efficient method

Abstract

Performance of traditional railway structure depends significantly on the behaviour of its support layers, particularly the ballast. This layer's rock particles are selected to ensure high mechanical strength, but traffic and mechanical maintenance break and wear the particles. Consequently, the layer incurs permanent deformations that degrade its strength and increase deformability and permeability. Particle physical characteristics, in particular those related to size and shape, influence their fragmentation and wear and must be studied accordingly. In addition, structural numerical models that represent individual particles, such as the discrete element method, have been increasingly used to model the infrastructure and therefore detailed geometrical characterization in the form of 3D digital models of the particles are necessary. This work contributes to this goal by investigating a contact-based cost-effective method that digitizes particle form and allows the determination of their geometric parameters. This method is described, compared with well-established laser scanning technique and then applied to study degradation of particles in Los Angeles and microDeval fragmentation tests.

An assessment of contact and laser-based scanning of rock particles for railway ballast

“…The authors are working in parallel in the utilization of photogrammetry for ballast particle scanning, that is, the process of building digital meshes from multiple photographs, relying on image recognition and matching algorithms for 3D models' reconstruction. This line of work aims at improved resolution at faster scanning speed, which will allow for the accurate quantification of other important geometrical features of the ballast particles, namely surface roughness [21].…”

“…Works such as [1,17] or, more recently, Guo [7] who proposes new parameters for ballast degradation based solely on analysis of 3D digital particle models, have employed laser scanning to investigate particles from different rocks, before and after testing, with coarser and finer meshes. Paixão et al [21] proposes a low-cost photogrammetry method that compares, in many aspects, favourably with laser scanning. At a smaller scale, Barbieri and Silva [2] aims to establish lower cost photogrammetry with electron microscope of very small rock particles and compares it with well-established tomography and x-ray tomography [22].…”

Discrete Element Modeling of Permanent Deformation Accumulation in Railroad Ballast Considering Particle Breakage

“…Several researchers have used expensive and complex image analysis approaches to create polyhedral particles for use in DE simulations (Paixão et al, 2001;Le Pen et al, 2013;Qian et al, 2013;Sun et al, 2014). However, such expensive imaging equipment to obtain the scanned 3D image of the ballast shapes are not readily accessible.…”

Digitalización De Formas De La Naturaleza Como Recurso Morfológico

“…Según la American Society for Photogrammetry and Remote Sensing (2004) "la fotogrametría es la ciencia y tecnología cuyo fin es obtener información cuantitativa fiable relativa a objetos físicos y su entorno mediante procesos de registro, medidas e interpretación de imágenes fotográficas" (p. 32) (como se cita en Moreno & Castillo, 2018). Dichas imágenes se analizan y se posicionan según sus características comunes y los píxeles de las características compartidas se asignan en 3D, dando como resultado una nube de puntos, las cuales poseen la información tridimensional (Paixão, Resende & Fortunato, 2018). Dicho de otra manera, la técnica captura información bidimensional mediante fotografías y las convierte en información tridimensional, obteniendo un modelo idéntico al original, tanto en forma, dimensiones, posicionamiento, color y textura.…”