[Cdt-l] accurate GPX track based on the new mapbook data?
public at postholer.com
Sun Mar 27 19:14:34 CDT 2011
First, here are 3000+ way points viewable in google maps. These include
Dan's, journalists, SPOT users, and others who have contributed their
data. This is a shot-gun blast of way points. The trail trace is a
hybrid of various sources and does not necessarily reflect the official
route. Warning, this CDT google map showing waypoints may kill your
browser, be patient, works great in FireFox 4 and IE9:
Thoughts on trail traces and maps. Imagine looking at a 7.5 minute map
(1:24K). Imagine the trail trace drawn on the map. The colored line
(trail trace) is going to be a least 20 feet wide, and more like 30.
Assuming accurate data, having a lat/lon point more frequently than 20
feet gains nothing in map quality as it wouldn't be displayed. If I had
hourly accurate tracks with 10K data points I'd grab only points that
were 20 feet apart and toss the rest. That's 264 points per mile. Much
more manageable without sacrificing quality. From a 1:24K map
perspective, 50 points per mile is quite fine.
The GPX data format is just that, a format. It speaks nothing of data
quality. The GPX format will hold accurate and inaccurate data equally
well. It will also hold professional and recreational data equally well! ;)
I've been dragging my feet about making some 1:100K and 1:250K overview
maps available for the CDT. If anyone has a need for these, let me know.
I could use the motivation.
More information about the Cdt-l