Parametric Surfaces for Augmented Architecture representation

Augmented Reality (AR) represents a growing communication channel, responding to the need to expand reality with additional information, offering easy and engaging access to digital data. AR for architectural representation allows a simple interaction with 3D models, facilitating spatial understanding of complex volumes and topological relationships between parts, overcoming some limitations related to Virtual Reality. In the last decade different developments in the pipeline process have seen a significant advancement in technological and algorithmic aspects, paying less attention to 3D modeling generation. For this, the article explores the construction of basic geometries for 3D model’s generation, highlighting the relationship between geometry and topology, basic for a consistent normal distribution. Moreover, a critical evaluation about corrective paths of existing 3D models is presented, analysing a complex architectural case study, the virtual model of Villa del Verginese, an emblematic example for topological emerged problems. The final aim of the paper is to refocus attention on 3D model construction, suggesting some "good practices" useful for preventing, minimizing or correcting topological problems, extending the accessibility of AR to people engaged in architectural representation

From Multiview Image Curves to 3D Drawings

Reconstructing 3D scenes from multiple views has made impressive strides in recent years, chiefly by correlating isolated feature points, intensity patterns, or curvilinear structures. In the general setting - without controlled acquisition, abundant texture, curves and surfaces following specific models or limiting scene complexity - most methods produce unorganized point clouds, meshes, or voxel representations, with some exceptions producing unorganized clouds of 3D curve fragments. Ideally, many applications require structured representations of curves, surfaces and their spatial relationships. This paper presents a step in this direction by formulating an approach that combines 2D image curves into a collection of 3D curves, with topological connectivity between them represented as a 3D graph. This results in a 3D drawing, which is complementary to surface representations in the same sense as a 3D scaffold complements a tent taut over it. We evaluate our results against truth on synthetic and real datasets.Comment: Expanded ECCV 2016 version with tweaked figures and including an overview of the supplementary material available at multiview-3d-drawing.sourceforge.ne

3DIR: exploiting topological relationships in three-dimensional information retrieval from BIM environments

An increasing amount of information is being packed into Building Information Models, with the 3D geometrical model serving as the central index leading to other building information. The Three-Dimensional Information Retrieval (3DIR) project investigates information retrieval from such environments, where information or documents are linked to a 3D artefact. Here, the 3D visualization/geometry can be exploited when formulating information retrieval queries, computing the relevance of information items to the query, or visualizing search results. Following reviews of literature in BIM and information retrieval, a clear gap was identified in the practice of information retrieval from BIM systems. The practical need for such a system was further specified using workshops with construction professionals as end users. A software prototype was developed, built on a commercial BIM platform. The 3DIR prototype creates an index of all text attached to the 3D model. The user can search for information by selecting specific 3D objects, specifying a spherical volume of the model and/or entering search keywords. This paper focuses on the exploitation of model topology. Relationships between 3D objects are used to widen the search, whereby relevant information items linked to a related 3D object (rather than information linked directly to a 3D object selected by the user) are still retrieved but ranked lower. Several such relationships between 3D objects were tested, whether explicitly encoded in the BIM information architecture or inferred from geometrical computations. An evaluation of the software prototype which exploits such topological relationships demonstrates its effectiveness but highlights the challenges to software users of added complexity. The system is subjectively rated comparably favorably. It is concluded that care needs to be taken when exploiting topological relationships, but that a tight coupling between text-based retrieval and the 3D model is generally effective in information retrieval from 3D BIM environments

Three-dimensional geospatial compact abstract cell complexes data structure for urban air pollution modelling

Understanding urban air pollution is important for sustainable urban development. Vizualization of urban air pollution modelling has been provided through the advancement of two-dimensional (2D) to three-dimensional (3D) Geographical Information System (GIS). However, current 3D GIS is still in its developing phase and focuses more on the geometry of the 3D city models. Presently, there have only been a few attempts in studying the topological relationships between 3D city objects as key elements in geospatial science. These topological relationships are vital for 3D traversal and 3D nearest neighbours information between 3D city objects in GIS. To address the lack of topological relationships in 3D GIS, Compact Abstract Cell Complexes (CACC) as a new topological data structure was developed in this research. CACC was developed by analyzing the existing data structure and identifying the limitations. Firstly, it was designed to store all the cycles that exist in different dimensions with the aim of articulating the connectivity in 3D city models. Secondly, it stored the nearest neighbours information by implementing the space-filling curve method called the Hilbert Curve. Functionally, CACC has the full traversal ability inside single and multiple connected components. Performance experiments proved that CACC requires 60% to 80% less disk storage as compared to other comparable data structures. The results have demonstrated that it is the most compact and requires minimal disk storage as well as being 90% faster in search queries of large 3D datasets. Upon validation, the implementation of CACC in urban air pollution modeling demonstrated the expediency of having a 3D topological data structure for 3D city models application. The research has developed and proved that CACC can identify topological relationships between 3D objects. Furthermore, its application can be extended to other 3D applications such as Building Information Model (BIM), Computer Aided Design (CAD), Computer Aided Engineering (CAE), web standards design, geospatial database design and disaster management and planning

Indexing 3D scenes using the interaction bisector surface

The spatial relationship between different objects plays an important role in defining the context of scenes. Most previous 3D classification and retrieval methods take into account either the individual geometry of the objects or simple relationships between them such as the contacts or adjacencies. In this article we propose a new method for the classification and retrieval of 3D objects based on the Interaction Bisector Surface (IBS), a subset of the Voronoi diagram defined between objects. The IBS is a sophisticated representation that describes topological relationships such as whether an object is wrapped in, linked to, or tangled with others, as well as geometric relationships such as the distance between objects. We propose a hierarchical framework to index scenes by examining both the topological structure and the geometric attributes of the IBS. The topology-based indexing can compare spatial relations without being severely affected by local geometric details of the object. Geometric attributes can also be applied in comparing the precise way in which the objects are interacting with one another. Experimental results show that our method is effective at relationship classification and content-based relationship retrieval

Requirements for Topology in 3D GIS

Topology and its various benefits are well understood within the context of 2D Geographical Information Systems. However, requirements in three-dimensional (3D) applications have yet to be defined, with factors such as lack of users' familiarity with the potential of such systems impeding this process. In this paper, we identify and review a number of requirements for topology in 3D applications. The review utilises existing topological frameworks and data models as a starting point. Three key areas were studied for the purposes of requirements identification, namely existing 2D topological systems, requirements for visualisation in 3D and requirements for 3D analysis supported by topology. This was followed by analysis of application areas such as earth sciences and urban modelling which are traditionally associated with GIS, as well as others including medical, biological and chemical science. Requirements for topological functionality in 3D were then grouped and categorised. The paper concludes by suggesting that these requirements can be used as a basis for the implementation of topology in 3D. It is the aim of this review to serve as a focus for further discussion and identification of additional applications that would benefit from 3D topology. © 2006 The Authors. Journal compilation © 2006 Blackwell Publishing Ltd

Consistency constraints and 3D building reconstruction

International audienceVirtual architectural (indoor) scenes are often modeled in 3D for various types of simulation systems. For instance, some authors propose methods dedicated to lighting, heat transfer, acoustic or radio-wave propagation simulations. These methods rely in most cases on a volumetric representation of the environment, with adjacency and incidence relationships. Unfortunately, many buildings data are only given by 2D plans and the 3D needs varies from one application to another. To face these problems, we propose a formal representation of consistency constraints dedicated to building interiors and associated with a topological model. We show that such a representation can be used for: (i) reconstructing 3D models from 2D architectural plans (ii) detecting automatically geometrical, topological and semantical inconsistencies (iii) designing automatic and semi-automatic operations to correct and enrich a 2D plan. All our constraints are homogeneously defined in 2D and 3D, implemented with generalized maps and used in modeling operations. We explain how this model can be successfully used for lighting and radio-wave propagation simulations