GrIMP data in QGreenland

[trey-stafford]

Ian Joughin reached out to us via email about adding GrIMP data to QGreenland (forwarded to QGreenland team members Trey and Matt). Consider adding data layers from GrIMP (probably as Internet-only layers).

Specifically, Ian says:

we have very compact layer definition files that link the data remotely that could be distributed with Qgreenland

including a GrIMP velocity mosaic, which is the most accurate product out there would be good too (see comparison with ITS_Live here - https://www.dropbox.com/s/qisqx8zobt8qkri/ISROPosterPortrait.jpg?dl=0).

I haven't updated recenlty, but here are some example layer definition files. The nice thing is you can quickly import the layer definition file for the file you are interested in

https://github.com/fastice/GrIMPQGISProjects

In principle the whole shebang can be loaded all at once, but it can create some problems. 1) it can take a few minutest to load on a slow connection, and 2) the number of open files the OS allows can be exceeded. This is something that can be reset to a bigger number, but novices may have a hard time with it. So its nice to just pick and choose which data set to load.

Another caveat is that gdal has to be installed, which I think is automatically installed with QGIS.

Also there is a bit of work to setup a .netrc file with the users NSIDC password. This process is documented here:

It could probably done with a simpler setup script. If your developers have a better way to authenticate with NSIDC, I would love to hear it.

Once everything is set up it works really well. Occasionally if it tries to do too much at once, it will time out. But just re-zoom or something else to force a reload and it works great. The best way to avoid this is not to turn more than a few layers on at once (the issue is NSIDC drops the connection if more than 15 accesses at once from the same IP). If browsing a single 25-m mosaic at a time, its really quick zooming in and out. Once zoomed to the right place, its easy to toggle other layers on an off (again its good to be disciplined about not just toggling everything on at once, which shouldn’t be a problem since you can only see one image at time anyway).

[trey-stafford]

We had a similar ticket in Jira. Notes from there:

Slack discussion for context: https://nsidc.slack.com/archives/CSXBA3ERE/p1675784454844809

Jupyter notebooks exist for creating QGIS project files with remotely hosted layers of Greenland Ice Mapping Project (GrIMP) data. How might users of QGreenland leverage this tool to their advantage? Could we integrate some of the work done for GrIMP into QGreenland?

See:

https://github.com/fastice/GrIMPNotebooks
https://github.com/fastice/GrIMPNotebooks/blob/master/qgisRemoteNotebook.ipynb

ITSLIVE has also done some work with QGIS projects:

https://its-live.jpl.nasa.gov/
https://its-live-data.jpl.nasa.gov.s3.amazonaws.com/documentation/ITS_LIVE_using_QGIS.pdf

[trey-stafford]

Looking at adding GrIMP velocity data in #663

[trey-stafford]

Testing out the GrIMP-products.qgs project file provided by the GrIMPQGISProjects repo, and it's very slow to load. About 5% after 5 minutes of waiting, and QGIS is otherwise completely unresponsive.

It sounds like a .netrc with NASA EarthData credentials are required to access the data anyway, which makes it a difficult sell for including these data layers as online-only options in QGreenland.

[MattF-NSIDC]

a .netrc with NASA EarthData credentials are required to access the data anyway, which makes it a difficult sell for including these data layers as online-only options in QGreenland.

I'm a "no" vote :) I've always been anti-EarthData Login (in principle only -- the people working on it are doing a great job), and this is a good concrete example of why. EarthData Login is (IMO) anti-FAIR (specifically the "A" and "I" parts).

[trey-stafford]

it's very slow to load

Just finished loading after an hour, and none of the layers are marked as unavailable (probably because I don't have the .netrc setup).

[MattF-NSIDC]

none of the layers are marked as unavailable (probably because I don't have the .netrc setup).

I would expect not having credentials would result in layers being marked unavailable. What am I missing here?