Enrichment of a 3D building model with windows using oblique-view ALS and façade textures

A wide range of applications using 3D building models exists; such as computer games, city marketing, disaster management, tourist information systems, simulations of noise propagation and surveillance of sustainable construction. Complete acquisition of large urban scenes has become feasible using multi-aspect-oblique-view ALS; however, automated generation of detailed 3D models, the main focus of this thesis, still poses a significant challenge. \ud \ud To enable enrichment of a 3D building model with windows, the 3D wire-frame building model and the ALS point cloud are first automatically co-registered. The novel approach to window extraction presented in this thesis exploits evidences about window positions in processed oblique-view ALS point cloud and façade image textures. Laser beam penetrates glassy window areas, and thus points found behind a segmented façade plane, projected onto the façade plane, give reliable evidence about intrusion positions. On the other hand, high values of gradient on a texture are usually due to window frames. These two facts are exploited when extracting initial window patches. Additionally, binary masks, obtained by region growing of homogeneous parts of façade textures, are used to eliminate certain façade artefacts and to improve shape of window patches. The assumption, that many windows of the same kind are on the same floor, is used for the refinement procedure. First, façade textures are divided into horizontal blocks, representing floors. Second, a search for non-similar window patch templates within each block is performed. Third, to obtain additional window patch positions, the chosen templates are cross-correlated along the respective block. \ud \ud Eleven façade planes of an existing 3D wire-frame building model are textured with extracted patches, representing windows and other intrusions. Despite different arrangements of windows, varying window sizes, and relatively strict evaluation method, the method results in 63% detection rate. What is more, the method is mostly data-driven and the detection rate outperforms the method using only oblique-view ALS (Tuttas & Stilla, 2013). The windows are well defined, since the basis for most of window patches are connected components of edges belonging to window frames

Automatic Filtering of Lidar Building Point Cloud in Case of Trees Associated to Building Roof

This paper suggests a new algorithm for automatic building point cloud filtering based on the Z coordinate histogram. This operation aims to select the roof class points from the building point cloud, and the suggested algorithm considers the general case where high trees are associated with the building roof. The Z coordinate histogram is analyzed in order to divide the building point cloud into three zones: the surrounding terrain and low vegetation, the facades, and the tree crowns and/or the roof points. This operation allows the elimination of the first two classes which represent an obstacle toward distinguishing between the roof and the tree points. The analysis of the normal vectors, in addition to the change of curvature factor of the roof class leads to recognizing the high tree crown points. The suggested approach was tested on five datasets with different point densities and urban typology. Regarding the results’ accuracy quantification, the average values of the correctness, the completeness, and the quality indices are used. Their values are, respectively, equal to 97.9%, 97.6%, and 95.6%. These results confirm the high efficacy of the suggested approach

3d virtual modelling of existing objects by terrestrial photogrammetric methods - case study of Barutana

Three dimensional virtual modelling of existing objects (buildings or structures) is applicable in various fields of science and practice: architecture, civil engineering, urbanism, geology, mechanical engineering, video games and movie industry, medicine, archeology, safety of people and goods, etc. Photogrammetry, as a method of obtaining data of three-dimensional spatial structures based on two-dimensional images, is used, thanks to a number of software packages, for creating 3D models of objects and other spatial structures. This study analyses terrestrial semiautomatic and automatic photogrammetric methods, both presented through process of creating 3D model of an old existing historical building - Barutana (military gun powder warehouse), built in Ottoman empire, located in the fortress of the city of Nis in Serbia. The aim of the paper is comparison of two photogrammetric methods - semiautomatic and automatic in accuracy and efficiency through case study of Barutana

Remote Sensing and Geosciences for Archaeology

This book collects more than 20 papers, written by renowned experts and scientists from across the globe, that showcase the state-of-the-art and forefront research in archaeological remote sensing and the use of geoscientific techniques to investigate archaeological records and cultural heritage. Very high resolution satellite images from optical and radar space-borne sensors, airborne multi-spectral images, ground penetrating radar, terrestrial laser scanning, 3D modelling, Geographyc Information Systems (GIS) are among the techniques used in the archaeological studies published in this book. The reader can learn how to use these instruments and sensors, also in combination, to investigate cultural landscapes, discover new sites, reconstruct paleo-landscapes, augment the knowledge of monuments, and assess the condition of heritage at risk. Case studies scattered across Europe, Asia and America are presented: from the World UNESCO World Heritage Site of Lines and Geoglyphs of Nasca and Palpa to heritage under threat in the Middle East and North Africa, from coastal heritage in the intertidal flats of the German North Sea to Early and Neolithic settlements in Thessaly. Beginners will learn robust research methodologies and take inspiration; mature scholars will for sure derive inputs for new research and applications

Towards a National 3D Mapping Product for Great Britain

Knowing where something happens and where people are located can be critically important to understand issues ranging from climate change to road accidents, crime, schooling, transport and much more. To analyse these spatial problems, two-dimensional representations of the world, such as paper or digital maps, have traditionally been used. Geographic information systems (GIS) are the tools that enable capture, modelling, storage, retrieval, sharing, manipulation, analysis, and presentation of geographically referenced data. Three-dimensional geographic information (3D GI) is data that can represent real-world features as objects in 3D space. 3D GI offers additional functionality not possible in 2D, including analysing and querying volume, visibility, surface and sub-surface, and shadowing. This thesis contributes to the understanding of user requirements and other data related considerations in the production of 3D geographic information at a national level. The study promotes Ordnance Survey’s efforts in developing a 3D geographic product through: (1) identifying potential applications; (2) analysing existing 3D city modelling approaches; (3) eliciting and formalising user requirements; (4) developing metrics to describe the usefulness of 3D data and; (5) evaluating the commerciality of 3D GI. A review of current applications of 3D showed that visualisation dominated as the main use, allowing for better communication, and supporting decision-making processes. Reflecting this, an examination of existing 3D city models showed that, despite the varying modelling approaches, there was a general focus towards accurate and realistic geometric representation of the urban environment. Web-based questionnaires and semi-structured interviews revealed that while some applications (e.g. subsurface, photovoltaics, air and noise quality) lead the field with a high adoption of 3D, others were laggards due to organisational inertia (e.g. insurance, facilities management). Individuals expressed positive views on the use of 3D, but still struggled to justify the value and business case. Simple building geometry coupled with non-building thematic classes was perceived to be most useful by users. Several metrics were developed to quantify and compare the characteristics of thirty-three 3D datasets. Results showed that geometry-based metrics such as minimum feature length or Euler characteristic can be used to provide additional information as part of fitness-for-purpose evaluations. The metrics can also contribute to quality control during data production. An investigation into the commercial opportunities explored the economic value of 3D, the market size of 3D data in Great Britain, as well as proposed a number of opportunities within the wider business context of Ordnance Survey

Designing the Urban Microclimate

This doctoral thesis presents research on the integration and transfer of knowledge from the specialized field of urban microclimatology into the generic field of urban design. Both fields are studied in order to identify crosslinks and reveal gaps. The main research question of the research is: How can the design of urban neighbourhoods contribute to microclimates that support physical well-being and what kind of information and form of presentation does the urban designer need in order to make design decisions regarding such urban microclimates? This question consists of two parts, which are addressed separately in the first two parts of the dissertation. Part 1 concerns an assessment of relevant knowledge on urban design by literature review, followed by a field study into the use of expert information in the urban design process. Part 2 discusses the influence of the urban environment on its microclimate and, consequently, the living quality of its inhabitants – both by means of literature review. Combined, Parts 1 and 2 serve as a basis for a framework for a design-decision support tool, which is discussed in Part 3. This tool is proposed as a means to integrate knowledge of the urban microclimate into the urban design process, bridging an observed gap. Urban design is concerned with shaping the physical environment to facilitate urban life in all its aspects. This is a complex task, which requires the integration and translation of different stakeholder interests into a proposition for the realization of physical-spatial constructs in the urban environment. Such a proposition comprises different planning elements in the following categories: spatial-functional organization, city plan, public space design and rules for architecture. During the design process, the urban designer has to deal with incomplete, often contradictory and/or changing constraints and quality demands as well as other uncertainties. He/ she handles this complexity by starting with a small selection of constraints, iteratively working to a design solution by incorporating an increasing number of constraints. The selection of constraints is subjective, depending on the design frame of the individual designer. In order to make design decisions, the urban designer requires diverse information. To establish how urban designers collect information and which formats and information levels they prefer, field research among Dutch urban designers was carried out. This consisted of a series of exploratory interviews and an online questionnaire. The results indicate that dissemination of expert knowledge to urban design should be focused on the orientation and sketch phases of the design process and should provide different layers of detail, using mainly visual information accompanied by explanatory text. The results furthermore show a remarkable discrepancy between the assigned significance of the urban microclimate for urban design and the frequency of inquiry on this topic; almost all interviewees and respondents consider the subject to be important, but a majority of them seldom collect information on it. This signifies a gap in the knowledge transfer process. It is important to bridge this gap, because the urban microclimate has a significant impact on the physical well-being of people. All components of the urban microclimate – solar radiation, daylight, wind, air quality and sound – affect the physical well-being of people, whether separately or in conjunction. Some of these effects are immediate, such as heat stress and noise annoyance; others develop over a longer period of overexposure or underexposure, such as pulmonary and respiratory diseases. Some cause discomfort, for example sleep disturbance; others can be life- threatening, such as heat stroke or skin and lung cancer. It is therefore vital that the urban microclimate is given considerable attention in the urban design process. The urban microclimate is to a large extent influenced by the city’s morphology, materialization and landscaping. This influence is exerted through different physical principles, such as reflection, absorption and evapotranspiration. Basic knowledge on how and to what extent the urban environment affects the urban microclimate and of the underlying physical principles, supported by design guidelines and examples/ reference projects, will enable urban designers to estimate the effects of their design choices on the microclimate themselves better, and help them create conditions for urban microclimates that favour physical well-being. In order to make this information available to the urban designer in a way that corresponds to his/her working process, a framework for a design-decision support tool was set up. Requirements regarding form and function were derived from the field of urban design, while requirements regarding content were derived from the field of urban microclimatology. The tool is proposed to be a web-based knowledge base, consisting of five main menu categories: “climate elements”, “plan elements”, “principles”, “guidelines” and “example projects”. Each category provides access to separate pages for underlying items, containing different layers of information, from general to detailed, that can be accessed through collapse menus or click-through functions. Hyperlinks between related items are provided to support different ways to access information. The main menu further gives access to background information on physical well-being and regulations and standards. Separate item pages can be added to a ‘shopping cart’, enabling customised information selection for a specific design at hand. Providing the necessary content for the tool requires further translation of expert knowledge into design information as well as additional research regarding: the plain and simple formulation of physical phenomena related to the urban environment; the integration of expert knowledge of separate microclimatological elements; the incongruity of parameters in microclimatological studies and urban design plan elements; and the presentation of information consistent with design and (design) communication purposes as opposed to evaluation purposes. To illustrate how expert studies can be rendered into design information, the impact of three selected plan elements - Floor Space Index (FSI), Ground Space Index (GSI) and orientation - on solar irradiation and wind was examined with the aid of numerical simulation tools. The results of the calculations for both climate elements were integrated in order to identify conflicts and matches. The emphasis of the study lay on showing trends and generating generic knowledge. Such knowledge is required to fill the proposed design-decision support tool with content. Answering the main research question, it can be concluded that various aspects relating to the morphology, materialization and landscaping of urban neighbourhoods can be employed to create conditions for a distinctive microclimate; urban microclimates often deviate substantially from the regional climate, and even vary within a few meters. Designing urban microclimates needs to be done with care as they affect the physical well-being of people significantly. In order to be able to do this, the urban designer needs information that ties in with his/her way of working and cognitive process. However, expert knowledge from the field of urban microclimatology does not fulfil this requirement and needs to be translated to information for urban design purposes. Aiming to give direction to this translation and facilitate the dissemination of expert urban microclimate knowledge to the urban design process, this research proposes a framework for a design-decision support tool. Requirements for the framework were derived from both the field of urban design and the field of urban microclimatology. A tool created according to the proposed framework will enable urban designers to practice climate-sensitive urban design, and, thus contribute to the physical well-being of people