Should Z bounds be included in the bbox field? about geoparquet HOT 4 CLOSED

I opened a PR to correct that omission last week: #88

But so that actually does include Z. I personally don't have a strong opinion on whether we should include it or not.

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Ah, sorry I missed that. For now I've dropped it from the metadata since a length-4 bbox is unambiguous regardless of dimension.

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Do other people have thoughts about including Z values in the bbox or not?

I think there are three options (in case of >2D data):

1. The bbox is always 4 values (only x, y dim), regardless of the dimension of the data
2. The bbox can be 4 or 6 values, so optionally including z values (leaving it to the data producer to decide whether it is useful)
3. Require that the bbox strictly follows the dimensionality of the data, so 4 values for 2D geometries and 6 values for 3D geometries.

Personally I agree that just having x,y bbox will typically be sufficient, so I would prefer 1 or 2.
Option 2 might become ambiguous, though, if we would allow M values at some point.

Another complicating factor is that we currently actually allow mixed dimensionality (in practice you can have WKB values with a mixture of 2D and 3D geometries). So at least allowing to only specify 4 values even if you have >2D data seems best. But I am also fine with for now only allowing 4 values.

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Closed by #88 and #145
The spec now clearly says the bbox has values for each dimension of the geometries.

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