Abstract
This project's principal intention is developing a structure from a motion thematic applied to an architecture field in both medium and large scale, in order to generate a cloud of points. These are obtained thanks to photographic footage, which can later be used during the H-BIM process. The matter of 3D digitalization is a very current issue for many countries including Cuba. The growth of such a technological application for tridimensional restitution of historical buildings is treated by giving special attention to those belonging to Havana's architectural and cultural heritage.
TopIntroduction
Photography, combined with new digital elaboration techniques, undertakes more and more scientific value. “Structure from motion” system’s technology allows real scene’s reconstruction starting from pictures and some basics measurements, used for scaling. Photo-modeling applied to architectural goods represent an awesome solution to document the state of existing buildings, being able to provide technicians of every necessary tool to later develop an information database which could be considered the basis for structured electronic information’s managing process. The Cuba’s concerned assignment under examination introduces photo-modeling techniques applied to complex cases in medium and large scale, leading to a wide comprehension of such techniques’ potentials and importance in architectural and urbanistic fields. Over a limited amount of time 59 buildings’ facades and decks, 2 fountains and 2 monuments afferent to five squares in Havana’s historical city center were surveyed: Plaza de Armas, Plaza Vieja, Plaza san Francisco, Plaza de la Catedral and Plaza del Cristo (Venegas Fornias, 2003). 30.000 m2 of floorings and as many vertical surfaces were analyzed overall. To carry out the survey we decided to use traditional, cheap and easily transportable mainstream tools, thanks to their low weight and space requirement, by means of which it was possible to create photo-realistic models containing geometrical information about buildings and squares material features, textures and surfaces’ colors. The investigation presented several obstacles: the need to minimally reduce every employed tool in term of conspicuity, weight and costs, to reduce times for survey and photographic shooting on field, to face all the problems gave by the continuous presence of people disturbing the operation. Least but not last the struggle deriving from the limited number of daily hours available to carry out photographic shoots as they require particular lightning conditions to be completed. The labor was regularly accompanied by a documental and archival research especially during the first phase, in order to give coherence to the paperwork by the recollection of useful information, supporting the construction of H-BIM models at the same time. Both the metric and photographic survey were fulfilled on field through traditional devices’ engagement. At first, handmade preliminary surveys and sketches were made with systematical criteria, immediately followed by the photographic set’s project (Baglioni, & Inglese, 2015). The aim is double: reducing the time for survey and recollecting every useful information for graphic restitution at the same time. During this first stage several problems emerged because of multiple immeasurable factors, like for example proper lightning conditions and immobile and mobile physical obstacles. Data and information recollection’s main characteristic was the great saving of time and money. The final work consisted in the restitution of every single element acquired on field, with the purpose of generating a substantial information body thanks to commercial hardware and software technologies. The graphic restitution stage was executed by methodological criteria as well, the aim was the obtainment of elaborations which could be implemented over the years for an holistic database’s evolution, convenient and functional for many reasons: building’s heritage restoration support, employment and development within new emerging technologies like HBIM (Heritage/Historic Building Information Modeling). The objectives are the furnishing of a new survey methodology and a shipping graphic restitution to catalogue historical, cultural and architectonical heritage; to deepen photo-modeling applied to architecture in medium and large scale topic; to generate a series of technical-documental valuable data on 3D models, including architectonic and urbanistic information on cities’ district; to show how the methodology in object was directly tested on a significant complex target such as Havana’s old town (see Figure 1) in the name of its limits, potentials and value’s authentication for the construction of an H-BIM model.
Key Terms in this Chapter
Geometric Model: Model without any chromatic characterization and information about the state of preservation of the surveyed object. It is very important and useful to understand the geometry, proportions, measurement and the relative position of the elements.
Digital Archives: Archives of documents memorized with informatics procedures. They contain a large amount of data on one or more topics related to each other whose management (i.e. insert, editing, and research data) is carried out by means of special software. Useful for the understanding, preservation and dissemination of data relating to the cultural heritage.
Intangible Characteristics: Identifiable non-monetary assets, such as heritage values and significance, that cannot be seen, touched or physically measured and are created through time and effort.
LoD: Level Of Detail, how much geometric detail is included in BIM components and refers only to the appearance of the object geometry not the amount of associated information.
Orthophotographs: A two dimensional ‘photo-map’ image of an object, building or landscape where the scaling error caused by survey has been digitally removed through reference to an underlying 3D surface model.
3d Models: Communication tool for the understanding and support of the object based on three-dimensional representation of a real object in a virtual space. Depending on the objective for which they are created, two types of model can be made: figurative 3d models and 3d models for scientific purposes. The figurative 3d models are aimed at achieving a convincing documentation of reality with a purely informative purpose; they are characterized by the identification of the geometry that describes the object represented by the clear and readability of its component parts. The 3d models for scientific purposes have a higher dimensional and formal correspondence with the real object and are characterized by high accuracy and reliability of the dimensions represented. In the first case, any survey's methodology is able to obtain data necessary for a correct realization of the final model, while in the second one needs to have qualitative accurate and highly precise survey data.
2d Models: Procedure for the communication of knowledge of the built environment and multidimensional elements based on schematization that leads to a reduction in the number of dimensions from three to two and that materialize on two-dimensional supports. Drawings that are conventionally represented elements of architectural and archaeological nature at different scales of representation, consisting of plans, elevations and sections. In order to communicate all the knowledge acquired about the surveyed object, two types of models can be made: geometric models and textured models. The first typology of model is characterized by the geometrization of the elements represented and show the morphology and the spatiality of the object; the other one makes explicit the actual configuration of the elements and shows graphic characterization indicating the quality of the surfaces and their state of preservation.
Structure From Motion: The science of making measurements from photographs. The input to photogrammetry is photographs, and the output is typically a map, a drawing, a measurement, or a 3D model of some real-world object or scene.
Tangible Characteristics: Physical attributes that are quantifiable, measurable and factual.
Scan-to-BIM: The process of creating, manipulating and placing native BIM components by directly referencing the underlying point cloud.