3 ms·
This doesn't stress the datum point quite enough. If you have an arbitrarily precise lat long, you still don't know where you are very well. If you don't know
by jofer 6y ago
This doesn't stress the datum point quite enough. If you have an arbitrarily precise lat long, you still don't know where you are very well.
If you don't know the datum of a lat long, you only know the location to within about a kilometer.
Datum matters. And yes, WGS84 is fairly common, but you will still very routinely come across lat/long or projected coordinates in other datums. NAD27 is the one that you'll encounter the most in the US, and it's about a 300 meter shift compared to WGS84 or NAD83. Others exist too and are frequently used.
Don't just record lat/long.
- jonas21 6y agoA few years ago, I visited the Greenwich Observatory and waited in line for hours to get a photo on the prime meridian. To my surprise, its GPS coordinates were not at 0 degrees longitude. It turns out that while older datums such as NAD27 use the Greenwich meridian, GPS is based on WGS84 which uses the IERS Reference Meridian. It runs through the park about 100 meters away from the observatory (and you can stand on it without waiting in line at all!)