Implement 3D Volume regridding

[philippjfr]

Implements basic 3D volume regridding only supporting mean downsampling and nearest upsampling for now.

• Double check array orientations
• Add tests
• Add docs

[jbednar]

Very cool, thanks!

[jbednar]

Suggested change

	floats, and 0 if int.
	floats, and 0 if int. Thus if 0 is not a suitable missing-value indicator,
	for your integer data, convert it to a float type before calling this method.

[jbednar]

Suggested change

	nan_value : int or float, optional
	Optional nan_value which will be masked out when applying
	the resampling.
	nan_value : int or float, optional
	Optional nan_value that will be masked out when applying
	the resampling.

How does this interact with the "nodata" attribute of the raster? Does it override it? Should clarify that here.

[jbednar]

Suggested change

	options include: nearest, linear.
	Options include: nearest, linear.

[jbednar]

@philippjfr , can you compare your approach here with #927 and see if there is anything you need to take from here? I haven't tried to see how the two binning approaches differ or are similar.

[philippjfr]

Having trouble seeing how they relate to each other. Isn't #927 going from points -> grids and this is going from grids -> grids?

[jbednar]

Right you are; this is 3D volume re-gridding, and the other is 3D volume gridding. So, the actual task is the other way around -- please check if anything from #927 is relevant to this one. Thanks!

[maximlt]

@philippjfr any update with this? Can we move forward?