Collada

Collada (COLLAborative Design Activity) is an interchange format for interactive 3D applications. Originally developed by Sony Computer Industry, now it is managed by the Khronos Group, a member-funded industry consortium, which now shares the copyright with Sony, Recently Collada has been well adopted by ISO as a publicly available specification, ISO/PAS 17506.

It is an XML-based schema that allows data exchange among 3D Digital Content Creation tools, such as SketchUp, Maya, 3ds Max, and Rhino. COLLADA files have the *.dae file extension, which stands for digital asset exchange.

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B-rep

In solid modeling and computer-aided design, boundary representation—often abbreviated as B-rep or BREP—is a method for representing shapes using the limits. A solid is represented as a collection of connected surface elements, the boundary between solid and non-solid.

Boundary representation of models are composed of two parts: topology and geometry (surfaces, curves and points). The main topological items are: faces, edges and vertices. A face is a bounded portion of a surface; an edge is a bounded piece of a curve and a vertex lies at a point. Other elements are the shell (a set of connected faces), the loop (a circuit of edges bounding a face) and loop-edge links (also known as winged edge links or half-edges) which are used to create the edge circuits. The edges are like the edges of a table, bounding a surface portion.

Compared to the constructive solid geometry (CSG) representation, which uses only primitive objects and Boolean operations to combine them, boundary representation is more flexible and has a much richer operation set. In addition to the Boolean operations, B-rep has extrusion (or sweeping), chamfer, blending, drafting, shelling, tweaking and other operations which make use of these.

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