Add GlacierMappingAlps dataset

[dcodrut]

This PR adds a a Multi-modal Dataset for Glacier Mapping (Segmentation) in the European Alps.

The dataset consists of Sentinel-2 images from 2015 (mainly), 2016 and 2017, and binary segmentation masks for glaciers, based on an inventory built by glaciology experts (Paul et al. 2020).
Given that glacier ice is not always visible in the images, due to seasonal snow, shadow/cloud cover and, most importantly, debris cover, the dataset also includes additional features that can help in the segmentation task.

Here's a sample extracted with the plot function implemented in the dataset:

A preprint is available here that describes in detail how the dataset was constructed.
For a shorter description check also: https://huggingface.co/datasets/dcodrut/dl4gam_alps.

[nilsleh]

Thanks a lot for the contribution :) I hope this first round of review is able to resolve the import xarray error that is preventing the unit tests from running. Once they are working, will take another look for anything else!

[dcodrut]

@microsoft-github-policy-service agree

[dcodrut]

Thanks a lot for the contribution :) I hope this first round of review is able to resolve the import xarray error that is preventing the unit tests from running. Once they are working, will take another look for anything else!

I hope it will be somehow useful. Happy to contribute and learn new things on the way :)
Thanks for the comments and please let me know if there are additional things I should change.

[adamjstewart]

I'm completely fine with adding xarray and netcdf4 as optional dependencies. We've been talking about adding xarray support for a long time. We're still not sure if it will be directly through xarray or something like rioxarray, but that doesn't matter for this PR.

[adamjstewart]

Can you resolve the merge conflicts so the tests run?