Spastic Topographic
Somebody's been geekin' hard on the topo maps. Have a look at some routes here:
http://staff.washington.edu/skykilo/Map/topogk.html
Can anybody think of more routes they'd like to see on that page?
http://staff.washington.edu/skykilo/Map/topogk.html
Can anybody think of more routes they'd like to see on that page?
posted by SkiSickness at 10:55 AM
19 Comments:
serious geekage. nice work. spider maybe? Canadian lines?
--Old E
spider
slipped in cider
drowning in sweetness
done deal - poetry to me.
what Canadian lines would you suggest?
I seem to recall you questioning the accuracy of my steepness table for Cascade lines... and now here you go make your own, and claim slope angles for 200ft vertical sections? I really don't think the TOPOs are *that* accurate!
My table shows some differing values:
Goode E face: 46 degress for 1700ft
Lib Ridge: 41 degrees for 4600ft
Fury NE face: 48 for 1600ft
Ben/Sky line on Spider: 47 for 1100ft (but includes cliffband at bottom which is covered by snow)
Yeah, well, I question everything. But it does seem more objective.
SO, since you disagree with my measurements, let's see yours, or what you get from mine. I think the topos all come from the USGS. They should be the same.
Did you measure straight lines only? I'm trying to follow the actual ski routes. I cut them into line segments to actually get the distance. If I took a straight line from where we started skiing steeps to where they got flatter, I'd get a much steeper value.
Show me some topos with lines, or what values you get from the same lines I've drawn. You have a table. I'm actually displaying how I made the measurement. Show me yours.
LET'S RESOLVE IT!
The best example on there is Liberty Ridge. If I take the straighter line, I get 46.7; if I take the line that faithfully follows what we skied, I get 41.8. How did you measure your distances?
The line I drew on Goode here:
http://www.mtnphil.com/Temp/GoodeMap.JPG
0.29 miles (1530ft), if you trust TOPO!.
1700ft vertical (my count of coutour lines)
atan(1700/1530) = 48 degrees.
Your line is a little different though. But I drew one like yours and it was still .29 miles.
fyi, I drew lines in TOPO!, like it seems you did, for measuring horizontal distance. Usually following the fall line ski route. If you draw traversey lines, you'll under-estimate the slope angle. (e.g. east face couloir on 3 fingers gets under-estimated at 45deg/1800ft, assuming it is off fall line like I think it is)
Contour lines I generally counted, since TOPO! doesn't give good elevation data.
I thought I was the only one that estimated slope angle from topo maps, and here I was just calculating it in my head. The likely accuracy of my calculations appears feeble in comparison with the precise scientific inquiry exemplified by SS, and further refined in Socratic dialogue with Lefty.
I recall a thread on TAY by a person with initials LS, which disputed the accuracy of topo contour lines. Something about how they didn't agree with GPS readings. While your arrows approach the bullseye, I fear you have not yet put all controversy to rest. Further data collection is in order.
-BB
Lefty:
Here's the deal. I used TOPO previously and I thought its distance measurements were crap. Any time I use TOPO to measure, for instance, distance along trails, I get a result that is decidedly short.
I used GIMP. I followed the lines I drew. I agree that this will not give an answer as steep as the gradient, but I want to find a consistent way to characterize a ski route as a whole. You may not like my technique. This is definitely open for further debate.
I'm sure topographic maps are inaccurate on micro scales, but they should give very decent estimates for larger distances.
I'll write more on that page in the near future to clarify exactly what I'm doing.
WORD
The only way to solve is with field research. I think we can assume we can get a fairly accurate elevation delta with maps or an altimeter. All that's needed then is a long ball of string you unroll as you ski. I'll make sure to bring one next time.
GPS is actually pretty good above treeline
Who carries GPS? Knot eye.
If someone wants to send me GPS data, I'll use it. But how fine of a scale does GPS measure? If it takes the distance of every turn's arc, then it'll give some seriously sandbagged angles.
Topo geekery version 2.0 is now online, with more detailed explanations of procedures.
Lefty and I had an in-depth discussion while enjoying powder yesterday and I think we've made amends. Conclusion: TOPO sucks, The GIMP rules. This is open-source route geekery.
Now, more suggestions and questions are always welcome.
I'd love to add routes from elsewhere, but my experience is limited. Anybody, please help! I emailed some in-the-know guys, but they haven't shown any desire to collaborate.
I like this stuff!
North Face of Robson(Canadian Rockies). When those guys skied it in the 90's they claimed it to be ~60 degrees; I am curious what you would come up with.
How about the headwall above the Mary Green Glacier on Bonanza.
1978 NE Face variation on Goode looks like the goods..
Glad you like it, nemo. It's easy to imagine 60 degree spots on the N Face of Robson. Sustained 60 degrees would be something else. I'll put it on there tomorrow if I feel able to draw a justifiable line on the topo myself. Otherwise, maybe I'll seek the expertise of those who have skied it.
Gotta go get ready and get some sleep to sneak a few face shots before work tomorrow!
My experience with canadian topo maps is that they aren't nearly as accurate as USGS. I've never seen topo maps so wrong as I have in the places I've visited in the Coast Mtns. I'm talking about the 1:50000 ones. There might be other series that are better.
ymmv...
I was leisurely looking for Canadian topos on the internet just now. All I can find are 1:50000 scale maps and it looks like I need to buy them. Does anyone know where to get them for free? Either way, the measurements probably wouldn't be as good as the numbers we're getting with the 1:24000 maps for the US.
I have that huge waterproof map of the Waddington Range that's widely available. I could play with that at some point.
More for Cpt. Nemo:
I measured where I think a steep ski descent would go above the Mary Green Glacier from 8840 to 9320, getting an average slope that converts to 54.8 degrees for 480 ft. Sounds pretty sweet. Don't tell the Holden shredders.
Ya, those Canadian maps can be problematic it seems. On a trip to the Fairweather Range, 11 years ago, we had such a difficult time finding maps with the proper scale that we just ended up flying out there with zeroxed copies of the Alaska Gazeteer. A bunch of Rookies we were!
I'll talk to THE GEOLOGIST to see if he has any insight on this topic.
Nice, fairly short pitch above the Mary Green there.
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