1. FILE FORMAT

To work with 3D mesh of building, two options show up more than any other, CityGML and IFC Format,both format allow different level of details from LoD0 to LoD4 (Level of Detail), here a short presentation of both format :

  • CityGML : CityGML is a file format is an open source 3D city modeling format to store landscape and models of city.CityGML project consist of multiple XML files and sometimes images to be used as texture.

  • IFC : IFC(International Foundation Class) is a file format based on the initiative from BuildingSMART(BIM) to increase portability between software in the consturction industry. The IFC format is a volume-based 3D representation , The file is very similar to object-oriented code, with numerous classes associated with various needs such as construction sites, tools, and materials.One of the difficulty is to interprete IFC objects for use in Kinetic programs.We most of the times end Up converting them to STL or MSH files format.

So for this project, we support different file formats as input:

  • STL: The STL (STereoLithography) format is widely used for 3D modeling. It represents 3D models as a collection of triangular facets.

  • MSH: The MSH format, used by Gmsh, is a flexible file format for mesh generation, storing geometric data and mesh information for finite element analysis.

  • PLY: The PLY (Polygon File Format or Stanford Triangle Format) is used for storing 3D data as a point cloud, including vertex and vertex normal associated, often used in 3D scanning and modeling.

And as output:

  • OFF: The OFF (Object File Format) is used to represent the geometry of a 3D model, storing information about the vertices, edges, and faces of the object.

  • OBJ: The OBJ format is a widely adopted format for 3D models, capable of representing 3D geometry including the position of each vertex, texture coordinates, vertex normals, and the faces that make up the 3D object.

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