Graphos – Open - Source Software for photogrammetric applications

This paper reports the latest developments for the photogrammetric opensource tool alled GRAPHOS (inteGRAted PHOtogrammetric Suite). GRAPHOS includes some recent innovations in the image-based 3D reconstruction pipeline, from automatic feature detection/description and network orientation to dense image matching and quality control. GRAPHOS also has a strong educational component beyond its automated processing functions, reinforced with tutorials and didactic explanations about algorithms and performance. The paper highlights recent developments carried out at different levels: graphical user interface (GUI), didactic simulators for image processing, photogrammetric processing with weight parameters, dataset creation and system evaluatio

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Drones—An Open Access Journal

Since the beginning of aviation, unmanned aerial systems have been a challenge for scientists and engineers

Analysis and Evaluation between the First and the Second Generation of RGB-D Sensors

With the recent introduction of the new Kinect II, the second generation of the well-known Microsoft Kinect sensors, the connection between RGB-D sensors, reverse engineering, and computer vision applications is reinforced. This new sensor is based on a time-of-flight technology, which differs from the previous generation of RGB-D sensors, including other devices, such as the Asus Xtion Pro and PrimeSense Carmine, which was based on structured light. Although characterized by better technical specifications, this does not neccessarily translate to the improvements in its application tasks. This paper aims at comparing quantitatively the Kinect II with respect to the first generation of RGB-D sensors in terms of two specific application scenarios: 1) 3-D reconstruction and 2) object recognition. To this end, we propose a novel data set with ground truth obtained with a metrological laser scanner, which allows a twofold analysis: 1) a performance comparison in terms of reconstruction accuracy and 2) a comparison in terms of object recognition and 3-D pose estimation. The obtained results confirm that the new version of the Kinect sensor demonstrate higher precision and less noise under controlled conditions. Furthermore, we provide a quantitative estimation of how much such factors turn out into an improvement in terms of object recognition rate and 3-D pose estimation

Comparative Analysis of Triangulation Libraries for Modeling Large Point Clouds from Land and Their Infrastructures

Although the generation of large points clouds from geomatic techniques allows us to realize the topography and appearance of the terrain and its infrastructures (e.g., roads, bridges, buildings, etc.), all these 3D point clouds require an unavoidable step to be conveniently treated: the definition of the surface that connects these points in space through digital surface models (DSM). In addition, these point clouds sometimes have associated attributes and geometric constraints such as breaklines and/or exclusion areas, which require the implementation of efficient triangulation techniques that can cope with a high volume of information. This article aims to make a comparative analysis of different Delaunay triangulation libraries, open or with academic versions available for the scientific community, so that we can assess their suitability for the modeling of the territory and its infrastructures. The comparison was carried out from a two-fold perspective: (i) to analyze and compare the computational cost of the triangulation; (ii) to assess the geometric quality of the resulting meshes. The different techniques and libraries have been tested based on three different study cases and the corresponding large points clouds generated. The study has been useful to identify the limitations of the existing large point clouds triangulation libraries and to propose statistical variables that assess the geometric quality of the resulting DSM

On the Use of Historical Flights for the Urban Growth Analysis of Cities Through Time: The Case Study of Avila (Spain)

Historical aerial images are a unique and relatively unexplored means of deriving spatio-temporal information for scenes and landscapes. Such historical imagery can be combined with photointerpretation and image-based 3D modelling techniques, providing the fourth dimension of time to 3D geometrical representations. This allows urban planners, historians, and other specialists to identify, describe, and analyse changes in scenes and landscapes. Urban growth has an important impact on the sustainable development of cities. An important step for the analysis of urban growth is the identification of different urban sectors. To this end, this paper proposes a methodology for the 4D urban growth analysis of cities through time using a free and open source software developed by the authors. This approach uses the latest advances in photogrammetry, including the so-called incremental Structure from Motion, to evaluate the urbanistic changes of a city by means of confronting two-point clouds from different eras. The objectives of this paper are twofold: (i) first, the processing of historical aerial images using modern photogrammetric techniques; (ii) second, deriving spatio-temporal information for urban cities, offering a method for researchers to identify changes over time. In order to validate this method, the urban growth of the city of Avila between 1956 and 2017 was assessed taking the historical American flight of 1956 and the digital aerial flight of 2017. The results were statistically assessed according to georeferencing quality, confirming that the approach developed can be used to support urban growth analysis through time and providing relevant data in 2D and 3D

RGB-D Sensors Data Quality Assessment and Improvement for Advanced Applications

Since the advent of the first Kinect as a motion control device for the Microsoft XBOX platform (November 2010), several similar active and low-cost range sensing devices, capable of capturing a digital RGB image and the corresponding depth map (RGBD), have been introduced in the market. Although initially designed for the video gaming market with the scope of capturing an approximated 3D image of a human body in order to create gesture-based interfaces, RGBD sensors’ low cost and their ability to gather streams of 3D data in real-time with a frame rate of 15 to 30 fps, boosted their popularity for several other purposes, including 3D multimedia interaction, robot navigation, 3D body scanning for garment design and proximity sensors for automotive design. However, data quality is not the RGBD sensors’ strong point, and additional considerations are needed for maximizing the amount of information that can be extracted by the raw data, together with proper criteria for data validation and verification. The present chapter provides an overview of RGBD sensors technology and an analysis of how random and systematic 3D measurement errors affect the global 3D data quality in the various technological implementations. Typical applications are also reported, with the aim of providing readers with the basic knowledge and understanding of the potentialities and challenges of this technology