[Cdt-l] Postholer CDT mapping
blisterfree at yahoo.com
Tue Oct 25 20:41:25 CDT 2011
It's sort of a legacy thing, I figure. Like the cdt-l itself. Not to speak for Jonathan, because I believe he's spoken loud and clear already, but the CDT-ROM has its roots quite a bit "back in the day," and much of it was just hand-drawn on maps, Photoshop-style. So there's simply no collection of coordinates behind what we see on those maps to string together into a GPX file for use by other developers / cartographers. There are 'desktop workarounds' to that problem, less problematic than trying to GPS all of that data in the field, but it would still be a formidable task to record the sum total of what's on the CDT-ROM into GPX format.
One solution could be to use Scott Morris' TopoFusion software ( www.topofusion.com ), the "User Map Library" feature, which allows you to overlay an external image file (such as each of the files contained on J Ley's CD) onto a coordinate-registered base map. You can choose from a slew of map types, so the protocol here would be to set the base map the same as that on J Ley's maps (USGS 7.5'). Then select the 'Draw Track' tool, and freehand draw over Jonathan's trail lines. Then save each line as a GPX track, preferably in the same color as on J's maps to distinguish what's official vs alternate CDT. Repeat the process for each map on the CD. Save all GPX files from a particular section (e.g., between town stops) in its own folder. Then merge whichever tracks as appropriate to create various border-to-border routes.
The problem with all that, from the perspective of what Scott Parks is trying to do, is that you still have multiple trails to consider. You have better accuracy and comprehensive data, but all the different routes, which are each valid in some way and can't be omitted without dumbing down the CDT experience, would continue to wreak havoc on the map automation process. And I don't know how a companion data book would be able to reflect so many multiple routes with different mileages and data points. Also, Jonathan's maps are chock full of commentary on each route and other stuff that wouldn't really be reducible to a data book-type collection of soundbites.
For the CDT, I think the main practical advantage to Scott's invention, as David Booth points out, are the digital base maps. If we could somehow lay those underneath all of Jonathan's wise scribblings, then that might up the field-worthiness of what we've already got. And let's face it, what we've already got is pretty hard to beat, in terms of the actual hiking experience. It's hard to fully appreciate that until you've actually used Jonathan's maps on this most amorphous of long-distance trails.
Scott has made a breakthrough, by adding up to date mapping
>information, but the nature of the hike is that there really is no
>On almost every map several alternatives exist. Jonathan has kept
>track of these and offers that variety.
>I dont think hikers want a single CDT.
>But I would like Jonathan's trails (official and alternative)
>available as a GPS trace (gpx file) as a single line or as a series
>of tracks that can be mixed and matched.
>I have used Out of Order's gpx files on my GPS and have found them
>very useful with few "errors", so there is a starting point for Scott.
>Perhaps Scott can sort out the Out of Order segments into "official"
>and "alternative" and then plot them on his master map.
>I have also used CDTA gpx points on my GPS and find them less useful
>as they are sometimes too far apart to show the detailed trail, but
>the CDTA gpx would define the CDTA's interpretation of what is
>I also lean heavily of Jim Wolf's descriptions and alternatives
>during the CDT planning process. I also seek out trail journals and
>also get a feel for the section from photos.
>This year I have kept gpx files of my actual route in Wyoming and
>northern Colorado. Looking back on these files I see quite a few
>places where I didnt follow exactly either Wolf or Ley routes.
>I guess it would be a matter of personal opinion of what constitutes
>my CDT and it is unlikely to be the same as your CDT.
>What is Scott's next step?
>Cdt-l mailing list
>Cdt-l at backcountry.net
>End of Cdt-l Digest, Vol 49, Issue 15
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