Although my library in Apache Baremaps probably plays a minor role only (PgBulkInsert for Postgres COPY protocol), it’s great to see it chugging on all this data day by day.
Even more annoyingly, during takeoff and landing, the flight map system intentionally disables any way to see your precise location, altitude, velocity and direction. The "cockpit view" pane that shows these when cruising becomes unavailable, and the airplane marker is also hidden beyond a certain zoom level. Presumably this is some kind of misguided security by obscurity measure to stop terrorists, who apparently aren't smart enough to carry mobile phones with GPS receivers.
Discussion: https://news.ycombinator.com/item?id=39990346
theguitarman•3mo ago
And then there’s GPS coordinate shift. From what I read, ITRF, ETRS89, and coordinates associated with epoch dates attempt to deal with this.
So, even though it may not matter as much for FlightAware maps, autonomous and GPS-based systems are a little worrying. Being overly dependent on them may have some be risk over time.
marklit•3mo ago
The Airport in Tartu, Estonia had a navigation upgrade last year in order to help mitigate navigation jamming that's taking place in the region. https://www.eans.ee/en/uudised/tanasest-saab-tartu-lennuvalj...
Defcon had a great talk on all the different navigational systems pilots can use and a note at the end that these shouldn't be decommissioned at the rate they're experiencing atm https://www.youtube.com/watch?v=wSVdfOn737o
phoronixrly•3mo ago
The point I'm trying to make is that there are more important sources of error before you get to tectonic movement and GPS drift... And OSM is plenty useful even without outstanding precision.
hdgvhicv•3mo ago
phoronixrly•3mo ago
cyberax•3mo ago
> The point I'm trying to make is that there are more important sources of error before you get to tectonic movement and GPS drift...
You can absolutely measure tectonic drift on the OSM maps! They've existed long enough for it to be actually significant in a lot of places if you download the old data.
This also comes up all the time when trying to overlap data from local agencies onto the OSM maps. You end up with parcel boundaries visibly off.
phoronixrly•3mo ago
As I said, 7-digit precision.
> You can absolutely measure tectonic drift on the OSM maps! They've existed long enough for it to be actually significant in a lot of places if you download the old data. > > This also comes up all the time when trying to overlap data from local agencies onto the OSM maps. You end up with parcel boundaries visibly off.
Yeah, assuming the person who added the features you're observing as 'visibly off' did not use 1-meter Bing imagery with a 10-meter offset...
ericpauley•3mo ago
Given the 100ndeg precision is across the full earth, this would be 1 part per 3.6 billion or 9.5ish digits of precision. The location of the decimal point when displaying it is irrelevant.
willtemperley•3mo ago
In GIS the gold standard for positional accuracy is the Root Mean Square Error, measured in real world distance units.
cyberax•3mo ago
9 digits, because there are 2.5 digits of precision in 0-360 degrees left of the decimal point.
cyberax•3mo ago
The coordinates do not align precisely in many locations, exactly because of the actual motion of the Earth's surface. Tectonic plates, aquifer depletion, land sliding down the mountain slopes, etc. For practical applications, there are steps in the data processing to fit the different datasets together ("registering" one of them). As long as you have timestamped maps, you can reasonably reconstruct the current WGS84 coordinates by fitting the data together.
defrost•3mo ago
Modern digital post WGS84 mapping is a breeze compared to the days of dealing with chains under tension and stitching together across differing ellipsoids and datums.
jvvw•3mo ago
efskap•3mo ago
jvvw•2mo ago
willtemperley•3mo ago
This is exactly what 4D deformation models are for:
https://proj.org/en/stable/operations/transformations/defmod...