Comment by renmillar
2 days ago
> what do you mean a latitude and longitude doesn’t mean anything without a bunch more info?!
Is the more info just the coordinate system like WGS84, or am I missing something else?
2 days ago
> what do you mean a latitude and longitude doesn’t mean anything without a bunch more info?!
Is the more info just the coordinate system like WGS84, or am I missing something else?
There are many different coordinate systems that aren’t WGS84, and there are different epochs associated with them as well. Some of the use latitude and longitude, some of them use easting/northing, etc.
The worst part is that if you don’t get it exactly right, you’ll still get answers that look right but are shifted by maybe 1-3m. As an example, we had a field team out with a Trimble survey stick with RTK (nominal accuracy 1-2cm) that they were using to cross-check data from our aerial survey platform. We had laid out a bunch of targets on the ground, which they surveyed the corners for. Most of the time there was a fantastic match between the aerial survey data and the ground truth data, but occasionally there was a pretty large offset. As I discovered WAY too late, exactly one of the cellphones that ran the Trimble app had its coordinate system set to one of the Canadian CSRS frames instead of WGS84: https://natural-resources.canada.ca/science-data/science-res...
Edit: naturally, they just handed me the coordinates in a CSV file that they’d captured. The Trimble app + whatever data collection app didn’t actually record the reference frame.