Efficient Real-Time Rendering of Building Information Models

A Building Information Model (BIM) is a powerful concept, since it allows both 2D-drawings and 3D-models of buildings or facilities to be extracted from the same source of data. Compared to a general 3D-CAD model a BIM is a different kind of representation, since it defines not only geometrical data but also information regarding spatial relations and semantics. However, because of the large number of individual objects and high geometric complexity, 3D-data obtained from a BIM are not easily used for real-time rendering without further processing. In this paper we present a culling system specifically designed for efficient real-time rendering of BIM’s. By utilizing the unique properties of a BIM we can form the required data structures without manual modification or expensive preprocessing of the input data. Using hardware occlusion queries together with additional mechanisms based on specific BIM-data, the presented system achieves good culling efficiency for both indoor and outdoor cases

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

A New Partitioning Method for Architectural Environments

Computing global illumination in a moderate time for complex environments and walking through them is one of the challenges in computer graphics. To meet this goal, a preprocessing is necessary. This preprocessing consists in partitioning the environment into cells and determining visibility between these cells. Most of the existing partitioning methods rely on the Binary Space Partitioning technique (BSP) which can be easily applied to axial environments. But for non axial scenes the BSP has an important complexity of O(n^3) in time to construct a tree of size at worst O(n^2), n beeing the total number of input polygons. Moreover this technique entails a too important number of cells which do not necessarily fit with the topology of the environment. We propose in this paper a model-based partitioning method which can be applied to non axial buildings. It results in a few number of cells fitting at best with the environment topology. The problem of visibilty calculation is not addressed in this paper

A New Partitioning Method for Architectural Environments

: Computing global illumination in a moderate time for complex environments and walking through them is one of the challenges in computer graphics. To meet this goal, a preprocessing is necessary. This preprocessing consists in partitioning the environment into cells and determining visibility between these cells. Most of the existing partitioning methods rely on the Binary Space Partitioning technique (BSP) which can be easily applied to axial environments. But for non axial scenes the BSP has an important complexity of O(n 3 ) in time to construct a tree of size at worst O(n 2 ), n beeing the total number of input polygons. Moreover this technique entails a too important number of cells which do not necessarily fit with the topology of the environment. We propose in this paper a model-based partitioning method which can be applied to non axial buildings. It results in a few number of cells fitting at best with the environment topology. The problem of visibilty calculation is not..