Load Volume from Nifti

We decided to store volumetric data in the NIfTI1 format, because the volumes can store spatial orientation data (as a transform), and be loaded natively into slicer. I'm not quite sure how to implement this into the Database class, though. In MATLAB, I created a Volume class that was essentially an xarray.DataArray - it has voxel data with units, named coordinate axes with values and units, a transform matrix, and a flexible attribute dictionary. I think we can probably use xarray.DataArray here as well, although nibabel.Nifti1Image, which is what nibabel.nifti1.load returns, may be suitable on it's down (although I'm not as comfortable operating on the underlying data). I know vtk has a number of volumetric data formats which I'm guessing will be used in visualization, as well, although again - ease of use for processing is also a factor. I'm probably going to try to load from .nii to an xarray.DataArray, but I welcome other suggestions

Start by reading the Database class and the existing volume-loading path, then compare the issue's proposed xarray.DataArray and nibabel.nifti1.load approaches for .nii data. Review how vtk may be used for visualization. Done means the project has an agreed representation and a defined way to load NIfTI1 volumes while preserving spatial orientation and processing metadata.