International audienceWe present a novel algorithm, IlluminationCut, for rendering images in the many-lights framework. It handles any light source that can be approximated via VPLs and highly glossy materials. The method effectively creates an illumination aware clustering of the product space of the set of pixels, and the set of VPLs. Our framework is flexible and achieves around 3 − 6 times speedup over previous state-of-the-art algorithms

Recent years have witnessed the development of various techniques and tools for the building code-compliance of IFC models. Indeed these are great efforts, but, still there is a gap for the fully automatic building code-compliance. This paper presents our research and development of Semantic BIM Reasoner (SBIM-Reasoner) which employs semantic technologies to meet the requirements of semantic verification of an IFC model. SBIM-Reasoner employs several preprocessors (IFC to RDF converter, Geometry Extractor) to build the semantic repository from the input IFC model. Once all the triples are generated from the initial data (.ifc file), Stardog is used to build a knowledge graph for the semantic verification. All types of inference and reasoning mechanisms for the semantic verification are applied over this knowledge graph to meet the requirements of verification. Knowledge graph over triplets enables freedom of extending RDF based Semantic IFC model, creation of newer vocabulary and formation of newer rules, concatenation of triplets to build rules with condition and constraints over IFC data, dynamic reasoning over the triplets based on the initial data of IFC model, etc. Finally, we tested our prototype by using several online IFC models. We conclude that semantic technologies provide more rich mechanisms and answer vast types of queries for the verification of IFC models. It provides powerful features based on SPARQL libraries and serves best for the automated code compliance and verification of IFC models.

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Compliance checking for building models, cities and territories involves formalizing a set of model schemas and constraints. In this context, we aim to achieve two goals: (1) achieve semantic interoperability between BIM (IFC) and GIS (CityGML), which help us represent building information in its details and its surrounding environment; (2) adapting of PLU rule into semantic queries. In this article, we will introduce (A) BIM and GIS interoperability approaches, and (B) connecting the interoperable models, with PLU levels. Our approach addresses (Prob1) interoperability between IFC and CityGML on building scale model, and (Prob2) the correlation between PLU rules and the multiscale model.

International audienceInstant radiosity methods rely on using a large number of virtual point lights (VPLs) to approximate global illumination. Efficiency considerations require grouping the VPLs into a small number of clusters that are treated as individual lights with respect to each point to be shaded. Two examples of clustering algorithms are Light-cuts [WFA * 05] and LightSlice [OP11]. In this work we use the notion of geometric separatedness of point sets as a basis for a data structure for pre-computing and compactly storing a set of candidate VPL clusterings. Our data structure is created prior to rendering, is view-independent and relies only on geometric and radiometric information. For any point to be shaded, we show that a suitable clustering of the VPLs can be efficiently extracted from this data structure. We develop the above framework into an accurate and efficient clustering algorithm based on well-separated pair decompositions which outperforms earlier work in speed and/or quality for diffuse scenes