1,721,538 research outputs found
Drone Mapping in Inner Areas: Strengths and Limitations
Full text linkPrecise and comprehensive metric documentation of inner areas presents unique challenges due to their inherent characteristics and variability. While achieving a complete digital record demands the use of various instruments and tools, not limited solely to on-site data collection but also encompassing the integration of existing cartographic resources, a relatively "new" mapping tool has proven to be especially valuable in projects that lie between cartographic mapping and single building documentation: drones. This manuscript discusses both the operational and regulatory aspects of employing drones to capture images and process them with photogrammetric techniques to create digital records for inner areas, with a particular focus on a research project on some inner areas of Southern Calabria. In addition to addressing technical limitations and challenges, the pilot, who is also considered a photogrammetry expert in this paper, must also understand the project's requirements by establishing a dialogue with other specialists who will utilize the photogrammetric outputs. Compared to more traditional and standardized cartographic mapping initiatives covering large areas or restoration and preservation projects focused on individual buildings, the documentation of inner areas using drones occupies an intermediate stage that still lacks a well-defined workflow.Una documentazione metrica precisa e completa degli insediamenti in aree interne presenta sfide uniche per via delle specifiche caratteristiche e delle variabilità che tali aree presentano. Se è vero che una raccolta digitale completa richiede l’uso di vari strumenti, non esclusivamente limitati alla mappatura in sito ma che includa anche l’integrazione delle risorse cartografiche esistenti, uno strumento relativamente nuovo per acquisire e processare immagini con tecniche fotogrammetriche è il drone. Il drone si è rilevato di particolare utilità in quei progetti o studi tra una mappatura a scala territoriale e la documentazione del singolo edificio. Questo articolo riguarda gli aspetti sia normativi che operativi relativi all’uso del drone per catturare immagini e processarle con tecniche fotogrammetriche, in particolare nel caso di piccoli insediamenti in aree interne, a supporto della creazione di archivi digitali, con particolare attenzione al contesto italiano nell’ambito di una ricerca sulle aree interne della Calabria meridionale. L’articolo discute inoltre il dialogo necessario tra il pilota, che qui si intende anche un esperto di fotogrammetria, con gli altri specialisti che utilizzeranno i dati raccolti e processati; ciò anche nell’intenzione di mettere in luce limiti e sfide che questo strumento possiede anche sul piano tecnico. Se confrontato con mappature cartografiche più tradizionali, sia che interessino un progetto a scala territoriale o il restauro di un edificio storico, la mappatura delle aree interne con l’uso del drone occupa una sorta di livello intermedio in cui manca ancora di un flusso di lavoro ben definito.A precise and comprehensive metric documentation of settlements in internal areas presents unique challenges due to the specific characteristics and variability of such regions. While it is true that a complete digital collection requires the use of various tools—not exclusively limited to on-site mapping but also including the integration of existing cartographic resources—a relatively new tool for acquiring and processing images using photogrammetric techniques is the drone. The drone has proven particularly useful in projects or studies that bridge territorial-scale mapping and the documentation of individual buildings. This article addresses both the regulatory and operational aspects related to the use of drones for capturing images and processing them with photogrammetric techniques, particularly in the case of small settlements in internal areas, to support the creation of digital archives, with a specific focus on the Italian context within research on the internal areas of Southern Calabria. The article also discusses the necessary dialogue between the pilot—who is also considered an expert in photogrammetry—and other specialists who will use the collected and processed data, aiming to highlight the limitations and challenges that this tool presents on a technical level. When compared to more traditional cartographic mappings, whether concerning a territorial-scale project or the restoration of a historical building, mapping internal areas using drones occupies a sort of intermediate level that still lacks a well-defined workflow
MULTI-affine misalignment removal from bracketed images for hdr photography
No full textA novel procedure able to align bracketed images acquired with a handheld camera is illustrated and discubed. The method is based on a system of linear equations solved via least squares, which provides the transformation parameters of Low Dynamic Range images acquired for High Dynamic Range photography. The method uses features automatically matched in multiple images and a mathematical formulation based on affine transformations simultaneously estimated for the whole dataset. This provides a new set of images with pixel-to-pixel correspondence along with statistics to evaluate the quality of image alignment
NETWORK DESIGN IN CLOSE-RANGE PHOTOGRAMMETRY WITH SHORT BASELINE IMAGES
Full text linkThe avaibility of automated software for image-based 3D modelling has changed the way people acquire images for photogrammetric applications. Short baseline images are required to match image points with SIFT-like algorithms, obtaining more images than those necessary for “old fashioned” photogrammetric projects based on manual measurements. This paper describes some considerations on network design for short baseline image sequences, especially on precision and reliability of bundle adjustment. Simulated results reveal that the large number of 3D points used for image orientation has very limited impact on network precision
INTEGRATION BETWEEN BUILDING INFORMATION MODELING AND GEOGRAPHIC INFORMATION SYSTEM FOR HISTORIC BUILDINGS AND SITES: HISTORIC-BIM-GIS
Full text linkThe paper presents a novel prototype of integrated Historic BIM-GIS able to deal with multi-source, -scale, and -temporal information. It combines elements from the cartographic scale to a more detailed level of detail towards the building. It can be defined as a 3D virtual environment with an associate (geo)database able to encapsulate heterogeneous data not limited to products derived from the geometric survey, notwithstanding digital recording and its deliverables play a fundamental role. The system also provides a good interoperability level so that BIM and GIS software can exchange information, avoiding the implementation of functions and tools already available in other software packages. The example proposed in this contribution is related to the system of fortified structures around the city of Sondrio. Here, a single 3D environment was developed to encapsulate information from the cartographic level in an area of more than 135 km2 to the scale of 1:1 for specific architectural elements
Metric Rectification of Spherical Images
Full text linkThis paper describes a method for metric recording based on spherical images, which are rectified to document planar surfaces. The proposed method is a multistep workflow in which multiple rectilinear images are (i) extracted from a single spherical projection and (ii) used to recover metric properties. The workflow is suitable for documenting buildings with small and narrow rooms, i.e., documentation projects where the acquisition of 360 images is faster than the traditional acquisition of several photographs. Two different rectification procedures were integrated into the current implementation: (i) an analytical method based on control points and (ii) a geometric procedure based on two sets of parallel lines. Constraints based on line parallelism can be coupled with the focal length of the rectified image to estimate the rectifying transformation. The calculation of the focal length does not require specific calibrations projects. It can be derived from the spherical image used during the documentation project, obtaining a rectified image with just an overall scale ambiguity. Examples and accuracy evaluation are illustrated and discussed to show the pros and cons of the proposed method
Network optimization and design in group-wise registration of terrain corrected satellite images
No full textDirect web-based access to ready-to-use huge archives of satellite images and cloud-based services for planetary-scale data processing (e.g., Google Earth Engine or Amazon S3) is making possible to analyze unprecedented amounts of remotely sensed images simultaneously. Multiple images can be exploited to improve traditional results achieved through on-premises (on-site) processing, coupling cloud offerings, and redundant image information. This paper will introduce the concept of image network optimization for the case of registration problems based on groups of terrain-geocoded images. The particular case of multi-image registration will be discussed, notwithstanding the proposed approach can be extended to oter practical issues, as illustrated in the paper. The concept of network design and optimization for satellite images is mathematically formulated and quantified with a multi-purpose objective function comprising precision, reliability, and cost. Results are illustrated with theory and numerical simulations carried out with a rigorous stochastic approach, in which the significance of the different input variables is estimated. The developed network-based approach allows one to reduce the number of external constraints, mainly focusing only on images and their increasing availability through web-services integrated by massive cloud computation capability
A trip to Rome: physical replicas of historical objects created in a fully automated way from photos
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