Add meaning of "co-located"

[MGomezN]

As an absolute beginner working with xarray and non-native English, the word "co-located" in this sentence was unclear: "Now we can download and open co-located topography and geoid grids." I had to read Ensaio documentation to understand both data sets have node spacing of 10 arc-minutes, the horizontal datum is WGS84 and there are 1081 x 2161 grid points in total. I conclude this is the meaning of "co-located". Can we explicitly say what co-located means and guide people working with different geoids/data sets on the requirements of the grids? I mean, direct people to some external tutorial where they learn how to "co-locate" grids. Thanks!

[leouieda]

Thanks for reporting @MGomezN! How about adding a definition in the glossary? In this case, co-located means that the grid points are at exactly the same locations. It's important because otherwise we can't add or subtract values since they wouldn't be aligned.

Is this something you'd like to add?

[MGomezN]

Great. I can add the definition, but I was also looking for an example of how to build those co-located grids from scratch, and for that, I don't have a tutorial at hand... unless I can point out this one? https://github.com/fatiando-data/lightning-creek-magnetic-grid/blob/main/prepare.ipynb

[leouieda]

Ah that's a good point! I built those using icgem and asking for the exact same boundaries and grid spacing. But I'm other case it would require interpolation.

This would name a good addition to the tutorials repo. Perhaps getting the Southern Africa gravity and topography and the global geoid and making 3 collocated grids from those.

[leouieda]

Maybe better to add the definition without the example first and then link to one when it exists?

[leouieda]

@MGomezN quick github tip: If you add the text "Fixes #138" to the pull request description, this issue will be automatically closed when the PR is merged (hence the part about related issues in the PR template. I know you like these sorts of automations 🙂