A Self-Assembly Portable Mobile Mapping System for Archeological Reconstruction Based on VSLAM-Photogrammetric Algorithm

doi:10.3390/s19183952

Abstract

Three Dimensional (3D) models are widely used in clinical applications, geosciences, cultural heritage preservation, and engineering; this, together with new emerging needs such as building information modeling (BIM) develop new data capture techniques and devices with a low cost and reduced learning curve that allow for non-specialized users to employ it. This paper presents a simple, self-assembly device for 3D point clouds data capture with an estimated base price under €2500; furthermore, a workflow for the calculations is described that includes a Visual SLAM-photogrammetric threaded algorithm that has been implemented in C++. Another purpose of this work is to validate the proposed system in BIM working environments. To achieve it, in outdoor tests, several 3D point clouds were obtained and the coordinates of 40 points were obtained by means of this device, with data capture distances ranging between 5 to 20 m. Subsequently, those were compared to the coordinates of the same targets measured by a total station. The Euclidean average distance errors and root mean square errors (RMSEs) ranging between 12–46 mm and 8–33 mm respectively, depending on the data capture distance (5–20 m). Furthermore, the proposed system was compared with a commonly used photogrammetric methodology based on Agisoft Metashape software. The results obtained demonstrate that the proposed system satisfies (in each case) the tolerances of ‘level 1’ (51 mm) and ‘level 2’ (13 mm) for point cloud acquisition in urban design and historic documentation, according to the BIM Guide for 3D Imaging (U.S. General Services).

Highlights

The tridimensional modeling of an object starts with its original design or with the process of acquiring the data necessary for its geometric reconstruction
This paper extends on past surveys of classical photogrammetry solutions, adopting an extended solution approach for outdoor environments based on the use of a simple and hand-held self-assembly device for data capture, based on images, that consist on two cameras: One, which data will be used to calculate in real time, the path followed by the device using a VSALM algorithm, while with other one; a high-resolution video recorded and used to achieve the scene reconstruction using photogrammetric techniques
The major innovations of this study are as follows: First, the proposed approach for the 3D data capture and the implementation of the visual slam (VSLAM)-photogrammetric algorithm has been materialized in a functional and low-cost prototype, which has been checked in an experimental test, the results of which have been presented in the context of the building information modeling (BIM) work environment

Summary

Introduction

The tridimensional modeling of an object starts with its original design or with the process of acquiring the data necessary for its geometric reconstruction. In both cases, the result is a 3D virtual model that can be visualized and analyzed interactively on a computer [1,2]. The applications of 3D models (virtual or prototype) are numerous and widely used; they are usually used in the scope of clinical applications [6,7], geosciences [8,9,10,11,12,13], cultural heritage preservation [14,15] and engineering [16] In this context, to address this wide variety of application areas, both data capture techniques and devices, as well as the specific software for data processing and management tend to be simplified.

Methods

Results

Conclusion