To 3D or Not 3D: Choosing a Photogrammetry Workflow for Cultural Heritage Groups

The 3D reconstruction of real-world heritage objects using either a laser scanner or 3D modelling software is typically expensive and requires a high level of expertise. Image-based 3D modelling software, on the other hand, offers a cheaper alternative, which can handle this task with relative ease. There also exists free and open source (FOSS) software, with the potential to deliver quality data for heritage documentation purposes. However, contemporary academic discourse seldom presents survey-based feature lists or a critical inspection of potential production pipelines, nor typically provides direction and guidance for non-experts who are interested in learning, developing and sharing 3D content on a restricted budget. To address the above issues, a set of FOSS were studied based on their offered features, workflow, 3D processing time and accuracy. Two datasets have been used to compare and evaluate the FOSS applications based on the point clouds they produced. The average deviation to ground truth data produced by a commercial software application (Metashape, formerly called PhotoScan) was used and measured with CloudCompare software. 3D reconstructions generated from FOSS produce promising results, with significant accuracy, and are easy to use. We believe this investigation will help non-expert users to understand the photogrammetry and select the most suitable software for producing image-based 3D models at low cost for visualisation and presentation purposes

Exploiting Repetitions for Image-Based Rendering of Facades

International audienceAbstract Street-level imagery is now abundant but does not have sufficient capture density to be usable for Image-Based Rendering (IBR) of facades. We present a method that exploits repetitive elements in facades – such as windows – to perform data augmentation, in turn improving camera calibration, reconstructed geometry and overall rendering quality for IBR. The main intuition behind our approach is that a few views of several instances of an element provide similar information to many views of a single instance of that element. We first select similar instances of an element from 3-4 views of a facade and transform them into a common coordinate system, creating a " platonic " element. We use this common space to refine the camera calibration of each view of each instance and to reconstruct a 3D mesh of the element with multi-view stereo, that we regularize to obtain a piecewise-planar mesh aligned with dominant image contours. Observing the same element under multiple views also allows us to identify reflective areas – such as glass panels – which we use at rendering time to generate plausible reflections using an environment map. Our detailed 3D mesh, augmented set of views, and reflection mask enable image-based rendering of much higher quality than results obtained using the input images directly

BigSUR: Large-scale Structured Urban Reconstruction

The creation of high-quality semantically parsed 3D models for dense metropolitan areas is a fundamental urban modeling problem. Although recent advances in acquisition techniques and processing algorithms have resulted in large-scale imagery or 3D polygonal reconstructions, such data-sources are typically noisy, and incomplete, with no semantic structure. In this paper, we present an automatic data fusion technique that produces high-quality structured models of city blocks. From coarse polygonal meshes, street-level imagery, and GIS footprints, we formulate a binary integer program that globally balances sources of error to produce semantically parsed mass models with associated facade elements. We demonstrate our system on four city regions of varying complexity; our examples typically contain densely built urban blocks spanning hundreds of buildings. In our largest example, we produce a structured model of 37 city blocks spanning a total of 1, 011 buildings at a scale and quality previously impossible to achieve automatically

The process of city block modeling using a procedural programming language

Tématem této diplomové práce je dělení bloků do parcel za použití procedurálního modelování. Hlavním cílem je vylepšení stávající metody OBB-based Subdivision, která využívá k dělení bloků pomocné obálky ve tvaru obdélníku. Zároveň je požadováno přizpůsobení metody českým podmínkám. První část práce se věnuje rozboru odborné literatury, která ukazuje vývoj a současný stav problematik řešených v rámci procedurálního modelování. Následuje návrh metodiky, která testuje změnu tvaru obálky na lichoběžník, respektive na čtyřúhelník. Na závěr jsou navrhované algoritmy testovány nad reálnými daty v CityEngine, který nabídl možnost využití procedurálního přístupu k automatickému generování 3D parcel. Celý proces byl regulován omezeními územních plánů vybraných obcí. Powered by TCPDF (www.tcpdf.org)The master thesis deals with a block subdivision into parcels using procedural modeling. The main goal focuses on improving of the existing method called OBB-based Subdivision that uses auxiliary envelopes of rectangle shape for splitting. It is required to adapt the method to Czech conditions as well. The first part focuses on the analysis of scientific publications, which describes the development and current situation of procedural modeling issues. Then the methodology of suggested algorithm is described that tests a change of the envelope to the trapezium shape, respectively to the quadrangle shape. In conclusion, the proposed algorithms are tested on the real data in CityEngine, which offered the possibility of using procedural approach to automatically generate 3D parcels. The whole process is controlled by the limitations of development plans of the selected urban areas. Powered by TCPDF (www.tcpdf.org)Department of Applied Geoinformatics and CartographyKatedra aplikované geoinformatiky a kartografiePřírodovědecká fakultaFaculty of Scienc

Aplicación de geotecnologías para la obtención de potencial fotovoltaico a partir de fotografía oblicua y datos LIDAR

Trabajo de Fin de Máster del Máster en Geotecnologías cartográficas en ingeniería y arquitectura, curso 2011-2012.En los últimos año, la aparición de la fotografía oblicua está revolucionando el mundo de la fotogrametría, ya que a diferencia de la ya más que conocida fotografía cenital, la fotografía oblicua permite recoger información que con una ortofoto convencional no se conseguiría; Fachadas de edificios, señalización vertical, etc. En el presente trabajo se pretende analizar el potencial que tiene este tipo de fotografía. Para ello, a partir de imágenes oblicuas, obtendremos el potencial fotovoltaico de las cubiertas que conforman el área de estudio. El proyecto se divide en tres grandes apartados; En una primera fase del trabajo, procesaremos las imágenes oblicuas con orientaciones norte, sur, este y oeste obtenidas a partir de un vuelo realizado sobre la capital guipuzcoana Donostia-San Sebastián. En vuelo original tiene una extensión de 20km2, aunque nos centraremos únicamente en el centro histórico de Donostia-San Sebastián. A partir de estas imágenes se generará una nube de puntos georreferenciada a partir de procedimientos fotogramétricos. En una segunda fase del trabajo, trataremos la nube de puntos obtenida a partir de fotografía oblicua y mediante diferentes procesados, extraeremos únicamente aquellos puntos que pertenecen a tejados, generando un modelo digital de elevaciones a partir de estos puntos. Por último, a partir de los resultados obtenidos en apartados anteriores, realizaremos un análisis fotovoltaico detectando cuales son los lugares óptimos para la colocación de paneles solares. El estudio se realizará únicamente basándonos en datos geométricos (Trayectoria solar, localización de edificios, etc.) y únicamente se analizaran las zonas potencialmente favorables, sin entrar en detalles del tipo de panel solar que habría que instalar

Procedural modeling technique for three-dimensional cadastre - case study of a 3D detailed building model

176 σ.Με το πέρασμα των χρόνων, η έρευνα επικεντρώνεται ολοένα και περισσότερο στην ενσωμάτωση της τρίτης διάστασης σε όλους τους τομείς. Ιδιαίτερα η έρευνα αυτή κρίνεται σκόπιμη και απαραίτητη όταν αφορά την απεικόνιση της περίπλοκης αστικής πραγματικότητας, με τις επικαλυπτόμενες χρήσεις γης και τα επικαλυπτόμενα εμπράγματα δικαιώματα, αλλά και τη διαχείριση της γης από ένα λειτουργικό κτηματολογικό σύστημα. Οι δυνατότητες εφαρμογής ενός τρισδιάστατου κτηματολογικού συστήματος έχουν μελετηθεί εκτενώς, με στόχο την επίλυση προβλημάτων τέτοιας φύσεως. Συνολικά, ένα ολοκληρωμένο τρισδιάστατο κτηματολογικό σύστημα πρέπει να περιλαμβάνει κτηματολογικά δεδομένα που απεικονίζονται στις τρεις διαστάσεις και να λαμβάνει υπόψη θεσμικές, νομικές και τεχνικές πτυχές ανάλογα τα ιδιαίτερα χαρακτηριστικά της κάθε χώρας. Ωστόσο, μέχρι σήμερα δεν υπάρχει κάποιο ολοκληρωμένο τρισδιάστατο Κτηματολόγιο εν λειτουργία σε κάποια χώρα του κόσμου. Φυσικά οι τεχνικοί περιορισμοί τείνουν να ελαχιστοποιούνται, όσο προοδεύει η τεχνολογία, ιδιαίτερα όσον αφορά την απεικόνιση σε τρεις διαστάσεις, ενώ συνολικά υπάρχει δυναμική πρόοδος στο συγκεκριμένο αντικείμενο. Στα πλαίσια της συγκεκριμένης διπλωματικής εργασίας μελετώνται τα βασικά ζητήματα επί του τρισδιάστατου Κτηματολογίου και συγκεκριμένα η χρήση της κανονιστικής μοντελοποίησης για την τελική παραγωγή ενός μοντέλου κτηρίου με υψηλό επίπεδο λεπτομέρειας (τρισδιάστατη μοντελοποίηση εσωτερικού χώρου και εξωτερικού κελύφους) στην περιοχή του Χαλανδρίου της Αθήνας. Το λογισμικό που χρησιμοποιήθηκε κατά βάση ήταν το CityEngine, που παρέχει τη δυνατότητα αξιοποίησης της κανονιστικής μοντελοποίησης.Over the years, research has increasingly focused on the integration of the third dimension in all science areas. Particularly, this research is justified and necessary when it relates to the representation of the complex urban reality, with overlapping land uses and overlapping property rights, and the land management with the use of a sufficient and functional cadastral system. The potentials of applying a three-dimensional cadastral system have been extensively studied, in order to solve such problems. Overall, a three-dimensional integrated cadastral system should definitely include cadastral data depicted in three dimensions and take into account institutional, legal and technical aspects depending on the particular characteristics of each country. However, nowdays, there is no three-dimensional integrated Cadastre in operation all over the world. Certainly, the technical restrictions tend to be eliminated because of the advances on technology, especially regarding the visualization in three dimensions, while this topic shows dynamic progress. Within the purposes of this thesis, the key issues for the three-dimensional Cadastre were studied and specifically the use of procedural modeling for the generation of a building model with high level of detail (three-dimensional modeling of the interior and the outer shell of the building) at Halandri of Athens. CityEngine was the software which was funtamentally used and enables utilization of procedural modeling.Βασιλική Δ. Κωστ