[pct-l] Accuracy of DeLorme Topos

[Jeff Moorehead]

>Has anyone checked the accuracy of the trail shown on
the DeLorme maps.

 I agree with the stated low accuracy of the PCT's placement on the Delorme 
Topos. However, there is one alternative that looks very good. The forest 
service trace offered at Postholer is actually very accurate and can be 
easily placed on the maps using the Delorme software. The trace was produced 
using GIS algorithms to extract the 'trail-layer' from satellite data. 
Prior to my hike last year, I embarked upon an ambitious project to produce 
Harrison-style maps of large sections of the PCT. Although this eventually 
became too time-consuming in the waning days of trip preparation, what I did 
manage to produce using the trace and the Topo program was both accurate and 
useful. I'm not sure where the Topo program gets its trace data, but it is 
pretty far off in many cases.

As an alternative, I also uploaded the entire set of Garmin proprietary topo 
maps of the PCT corridor into my Garmin 60CS prior to the trip. To me, 
having a GPS with color maps is one of the best uses of this technology. The 
PCT does not appear on many of the maps, but it does on all those 
encompassed by National Parks, and curiously, it is very accurate in those 
areas where the PCT was 'built' by subsuming other existing trails (good 
examples are the Oregon Skyline Trail and the Cascade Crest Trail). On more 
than one occasion, the Garmin GPS, along with its internal maps, helped me 
navigate some tricky stretches. One was during a complete white-out 
experienced at dusk in Oregon's Mt. Jefferson Park-- I relocated the trail 
using the map/GPS combo. Besides, it was fun to always check position and 
linear distance to landmarks such as Mt Shasta, the Canadian border, and 
Campo. Gave me something to do during those boring rest stops.
Whiptail