Allowing to provide (within a tileset) the (json) schema of the data held in the batch table

[EricBoix]

The problem

When handled over a tileset that has a batch table, there is no internal (to 3DTiles standard) means to retrieve the types (e.g. json schema) of the data (held in the batch table).
Although the structure of a batch table data is simple (collection of attributes) one has to guess their respective semantics and type. Or one has to channel that information outside of the channel that goes from the upstream 3DTiles production to its current consumption.

Hints/Notes

3DTiles-Next introduces the 3Dtiles_metadata extension that allows to attach a (json) schema field on some entity types (tiles, tileset, content).

Two possible technical ways for solving this issue

• through 3Dtiles_metadata modification:
  allow the 3Dtiles_metadata to be attached to the "batch table" entity type ?

• through the definition of a new 3DTiles_batch_table_schema extension:
  this alternative solution would consist in defining a 3DTiles_batch_table_schema extension (a couple lines max)
  that allows the attachment of a metadata schema to a batch table.

[jailln]

Good idea! Note that the type of each attribute is defined in the JSON Header when storing the batch table content as binary.

For full JSON batch table cases, another possibility would be to propose a modification to the 3D Tiles standard directly, especially since there is a version 1.1 in the making? Maybe to be discussed in an issue on the 3D Tiles repository?

Just my two cents :)