two dimensions out of three

[cellio]

It's funny to see (well, hear) my phone's navigator app react to parking garages. "Do X... oh ok you're going north so do Y... oh you're going west so do Z... oh you're going south do A... oh you're going east do X which I'll pretend I haven't said before..." -- iterate until you reach the exit. It doesn't respond to elevation, only latitude/longitude.

I can think of three possible reasons for this, and I wonder which it is (or if it's something else I haven't thought of):

1. The GPS in the phone doesn't detect altitude.

2. The map data (Google's, in this case) doesn't record elevation. It does you no good to know that the GPS is at a certain elevation if the app can't tell that that's 200 feet above the road, after all.

3. The GPS and map data are available, but the app isn't programmed to take it into account. How often does this really come up, after all?

Comments

[eub.livejournal.com]

Now I'm curious just how high an altitude GPS receivers (consumer, specialty, military) are programmed to solve for. Do they actually handle when their location is above the satellites? Just based on the precision of their ranging, it should be possible to distinguish between convexity and concavity of satellte 'shell' (obvs after they've acquired 4+ satellites). But if dropping that capability saved the designer a millisecond or a dime, I have to assume they'd shed one geeky tear and drop it instantly.

If they do support it, I hope they maintain test coverage. :)