64 bit DEM data will silently report lossy NoData values

[Ryanf55]

Environment

• OS Version: Ubuntu 24
• Source or binary build?
  Binary

Description

• Expected behavior: If 64 bit datasets are not supported yet, a user attempting to load one should get a warning/error that it's not yet supported
• Actual behavior: 64 bit nodata is silently handled incorrectly

GDAL has separate API's for 64 bit datasets, such as GetNoDataValueAsInt64

Per the docs: For rasters of type GDT_Int64 or GDT_UInt64, using this method might be lossy if the nodata value cannot exactly been represented by a double. The current method used in gz-common is only GetNoDataValue.

Ubuntu 22 ships with GDAL 3.4, which does not support 64 bit versions of GDAL, so these terrains can not be loaded. Newer platforms make that possible.

I would consider this use case small, so the easiest solution would just to report a warning it's not yet supported. I don't think many people use data that precise.

Steps to reproduce

TODO

1. Finda 64 bit dataset with NoData values

2. Load it

3. Check the NoData value is not correct

Output

TODO