What is difference between b3dm and gltf ?
When to use b3dm and when to prefer gltf over b3dm ?
asked Feb 23, 2018 at 14:51
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Update, 2021-11-10: b3dm is being retired. 3D Tiles is upgrading to a new version dubbed "3D Tiles Next," and the b3dm wrapper is being replaced with raw glTF 2.0 (GLB) files plus an extension, according to the blog.
b3dm ("Batched 3D Model") is part of the 3D Tiles specification, and indeed b3dm uses glTF as its payload to deliver 3d geometry.
A single glTF file delivers a (relatively) small amount of localized 3D geometry, along with materials, textures, and other metadata needed to render it on a client. The 3D Tiles standard provides a mechanism to specify a hierarchy of geo-located glTFs at different resolutions. For example, a vehicle may be easily portrayed in a single glTF file, but a whole city with all of its buildings and trees would need to be broken up into 3D Tiles, using multiple glTF files internally.
(Disclaimer: I work for the company that was originally responsible for b3dm and 3D Tiles, but I'm not on that particular team myself and I don't speak for them).
