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CesiumGS / 3d-tiles

Specification for streaming massive heterogeneous 3D geospatial datasets :earth_americas:
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3DTILES_implicit_tiling: Availability Buffer Endianness #547

Closed nithinp7 closed 1 year ago

nithinp7 commented 2 years ago

Pictures like this one in the implicit tiling spec are slightly misleading in that the availability bits appear in order (i.e., it appears to be big-endian). An extra warning or clarification about the actual little-endianness following those set of pictures may prevent some confusion. Since this is a bitstream (as opposed to a typed buffer or even bytestream), the endianness actually matters in this case since client implementations will need to create a way to access specific bits within a byte.

javagl commented 2 years ago

The Subtree File Format section mentions

Subtrees are stored in little-endian.

But I agree that this could be pointed out near the diagrams, or clarified by adding an "Index in bitstream", similar to this image:

Cesium Availability

javagl commented 1 year ago

The extension became core in 1.1 and is therefore finalized. It does contain the information about endianness. We may consider pointing that out more prominently or changing the images for future versions, but until now, it did nto seem to cause any confusion, so I'll close that for now.