One problem is that using position to get altitude would require a detailed elevation map and that would use a lot of storage space or require internet. But el

One problem is that using position to get altitude would require a detailed elevation map and that would use a lot of storage space or require internet. But elevation maps are not detailed enough and position is not accurate enough to get accurate elevation. Think about standing on trail along steep slope. The position not being that accurate is fine since you know you are on trail. But altitude could vary wildly going up or down slope, or even up or down trail. It is probably similar to GPS vertical accuracy, but were going for more accuracy that barometer provides.