*PSA* - Ranked Lists Changing based off LiDAR Analysis

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ekalina
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by ekalina »

Scott P wrote: Wed Oct 27, 2021 2:18 pm
ekalina wrote: Wed Oct 27, 2021 1:46 pm Telemetry means use of GPS, right? Does it mean someone walked a GPS receiver up to the summit and read off the elevation?
No to both. It means it was done by photogrammetric methods when they drew in the contours in from aerial photographs. Most telemetry elevations on the quads predate GPS.
Very interesting, thanks! I'd expect the uncertainty to be pretty big in that case. I never paid much attention to whether the elevation marked on the map was written next to a survey benchmark, x, or nothing. Now I will!
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by Candace66 »

Wow, this is going to be interesting! :-D A big thank-you to John and everyone involved. 8) \:D/
goingup wrote: Mon Oct 25, 2021 12:09 pm As long as Sunlight Spire becomes a Colorado 14er eliminating 99.999999% of finishers I am okay with all of this. :-D
:twisted: :lol:

As a reminder, Gerry Roach pointed out years ago (in the 3rd edition of "Colorado's Fourteeners") that the NAVD88 vertical datum added five feet each to Sunlight Peak and Windom. So it's likely the Spire also "grew" five feet...taking it to an even 14,000'.
Anima wrote: Tue Oct 26, 2021 7:14 pm Through some quick googling, I found that LiDAR Data can be found here:

https://prd-tnm.s3.amazonaws.com/LidarE ... dex.html#/ ...
Darn, it's not available for the Saddle Peak Hills range in California, which has three candidates for the high point. :-k
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by bdloftin77 »

ekalina wrote: Wed Oct 27, 2021 4:05 pm
Scott P wrote: Wed Oct 27, 2021 2:18 pm
ekalina wrote: Wed Oct 27, 2021 1:46 pm Telemetry means use of GPS, right? Does it mean someone walked a GPS receiver up to the summit and read off the elevation?
No to both. It means it was done by photogrammetric methods when they drew in the contours in from aerial photographs. Most telemetry elevations on the quads predate GPS.
Very interesting, thanks! I'd expect the uncertainty to be pretty big in that case. I never paid much attention to whether the elevation marked on the map was written next to a survey benchmark, x, or nothing. Now I will!
Looking through old topo maps from https://ngmdb.usgs.gov/topoview/viewer/#4/39.98/-100.06 , the earliest map I found Sunlight Spire's estimated telemetric elevation on was the 1964 7.5' quad, 1967 edition. The map in the screenshot below has some info on how they obtained all their data. Useful website! Just click on the map, and you get a bunch of map results for that location.

LoJ's CalTopo layer (https://listsofjohn.com/mapf?lat=37.624 ... 15&t=c&d=y), shows control stations on Eolus, N Eolus, and Windom. The N Eolus one shows up in the screenshot below, and the others show up in the 1973 - 1975 edition map.

The National Map has LiDAR available for this area - I'll see if I can take a look at that sometime soon.
1964 Storm King Quad, 1967 Edition
1964 Storm King Quad, 1967 Edition
SunlightSpire.png (977.85 KiB) Viewed 2596 times
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by Candace66 »

jkirk wrote: Tue Oct 26, 2021 11:50 am As much as I'd like to keep the cat in the bag until a more thorough listing is available, I'll share my findings thus far. Some of it is random, because there are areas I have been wanting to visit and seeking out "new peaks." Since I'm doing the work, I may as well be selfish about what comes first. :roll:

The goods:
https://listsofjohn.com/lidar/lidar.php
Eventually, will any peaks demoted from ranked to unranked (I imagine there will be a few) be highlighted in another color?
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by DArcyS »

Boggy B wrote: Wed Oct 27, 2021 11:28 am And, the ranking criterion isn't subjective--it's 300 feet.
I see where you're coming from. Perhaps the more accurate statement is the selection of the 300' criterion as a "rule" is subjective (and one of opinion), while the application of the 300' criterion is objective (either its prominence is or it isn't 300').
bdloftin77 wrote: Wed Oct 27, 2021 12:36 pm
DArcyS wrote: Wed Oct 27, 2021 2:09 am John initially called the soft ranked peaks the "elephant in the room," which is indicative of the uncertainty of using two points to determine whether or not a peak is ranked. The statistically better way to determine whether a peak is ranked is to count the number of contour lines "crossed" from the saddle to the summit, as contour lines are created from a multitude of points (eh, I'll avoid the hyperbole that mathematically there's an infinite number of points in a line).

[...]

Given the lists are going through a transformation, at this point maybe some thought should be given to now using contour lines for the ranked peak criterion. Perhaps this might alleviate the burden of obtaining point elevations via LiDAR. In this day and age of computers, maybe you have multiple lists, e.g., the historic USGS list, the LiDAR list, the 8 contour line list, etc., noting that when it's all said and done, selecting the ranking criterion is quite subjective.
Kirk's algorithm takes into account all the LiDAR points near the saddle in both the nearby valleys and both ridges and calculates the lowest point on the ridge. He cross-checks this with the interpolated saddle, double-checking everything if the LiDAR saddle is fairly different. He's also making sure the LiDAR classes are filtered such that any trees and man-made structures are not picked up. Trust me - he's being very thorough, and using more than "just one LiDAR point." Looking through the metadata for a few counties from the CO Hazard Map website, the vertical accuracy of the LiDAR is ~0.24 ft. I'd much rather use cutting-edge data like this than counting contours for ranked peaks (in some areas, many contours are wildly inaccurate, especially in very rough terrain). I'm all for refining versus scrapping the current 300' system. If you'd like to do your own work and create contour-counting lists of your own, that's great! Yes, it'll take some time. But these results will be extremely accurate.
Thanks for the info, pretty interesting.

Perhaps my comments are more along the lines of hindsight is 20-20 and using contour lines would've eliminated the guessing game involving soft rank peaks. My earliest list goes back to Garratt & Martin published in '89 that gives a "rise" from the saddle for each peak in feet (and they probably adopted this format from Trail & Timberline). It's pretty easy to decide upon that criterion under those circumstances for they couldn't predict what would occur in the future in terms of peak lists and the uncertainty of soft ranked peaks. I think I was trying to convey that counting contour lines only leads to hard ranked peaks, with the certainty of this technique being a plus as there's no issues with the inexact elevations of saddles and summits. As for errors associated with contour lines, missing contour lines are bad, but if they're all off by x amount of feet, then that error is irrelevant

Accuracy for the distance between the saddle and summit is good, but it's not like we're calculating fundamental physical constants that have an effect on engineering projects. My suggestion was in the interest of the effort involved in extracting LiDAR data. All things being equal where a computer fully crunches the numbers, yes, LiDAR wins. But what's good enough? I'm aware of somebody who wrote a program that did the counting of the contour lines to determine ranked peaks, and I think his results were close to John's results (I forget the exact post on John's forum, many years ago, it's been awhile). Anyways, John's project, he can do as he pleases.
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by Boggy B »

DArcyS wrote: Wed Oct 27, 2021 7:52 pm ...
A missing contour line at an unsurveyed peak (or an errant contour line at an unsurveyed saddle) indicates there are really more contours between that peak and its saddle; even if all the surveyed elevations are off by -12 feet, that peak still has +1 contours, which means that however many contour lines you choose for your system, if the peak formerly had "X-1 Contours of Prominence," LiDAR has now found it to be ranked, by your own criterion. So, unfortunately, John still has work to do.

And I think anyone pursuing a list of ranked peaks has a stake in knowing definitively the scope of these objectives, by the criteria upon which they're based, and if John didn't take it upon himself then someone else would sooner or later. Eventually summit and saddle points and elevations based on the latest DEMs will be crunched automatically, made available via public APIs, and integrated into a thousand generic topo sites. I was going to do something big with contourlines.com, but I'd be willing to let it go for $500.
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by DArcyS »

Boggy B wrote: Wed Oct 27, 2021 11:40 pm
DArcyS wrote: Wed Oct 27, 2021 7:52 pm ...
And I think anyone pursuing a list of ranked peaks has a stake in knowing definitively the scope of these objectives,...
Unless they just climb them all, that takes care of the problem too, right? :)
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by Candace66 »

I'm still blown away by the huge change in prominence for The Castles East. From 280' on the map to 452' per LiDAR.

How could people not realize it was ranked?! Was it simply denial? :^o :mrgreen:

Has a difference of that magnitude (or anything close to it) been calculated for any other peak analyzed so far?
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by bdloftin77 »

Candace66 wrote: Mon Jan 31, 2022 11:34 pm I'm still blown away by the huge change in prominence for The Castles East. From 280' on the map to 452' per LiDAR.

How could people not realize it was ranked?! Was it simply denial? :^o :mrgreen:

Has a difference of that magnitude (or anything close to it) been calculated for any other peak analyzed so far?
Incorrect/missing contours! I believe John and others did try to investigate using a photo-analysis program to determine heights, but they'd assumed that the summit area was relatively correct, and the saddle might have only been slightly off. The saddle is close to reality (16' off), but the map summit area was missing quite a few contours, making a difference of 172' from the interpolated prominence based off the map to lidar prominence. If I remember correctly, John said The Castles West was also missing summit contours, throwing off their photo-analysis by quite a bit relative to other peaks in the area.

Sharks Nose in WY (one of Eli's newly ranked 12ers) jumped from 129' of prominence to 304'. The summit spot elevation was off by 34', but the saddle had spurious contours (much deeper saddle in reality), and was off by 141'. A total of 175' difference from the interpolated prominence based off the map to lidar elevations. Lidar didn't completely catch the bottom of the saddle either due to it being so narrow and deep, so it likely has even more prominence.

There's definitely a big possibility of finding surprises in peaks that weren't even previously soft-ranked. Haven't yet heard an update from John about the P240 prominence list. Many of these aren't even listed peaks in LoJ, either.
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by -wren- »

Let me know if I’m missing something in the below modified list.

Per LiDAR, there is now one less ranked 13er, 583 total.

We gain 8 from newfound prominence values.
- UN 13555, 295 > 302
- UN 13545, 285 > 307
- Telluride Peak, 289 > 597
- Peak Ten, 280 > 322
- UN 13472, 292 > 310
- Peak Eight, 288 > 330
- Ellingwood Ridge, 280 > 305
- Kendall No. 2 BM, 286 > 348

5 12ers are promoted to 13ers.
- Peak 8, 12987 > 13005
- Overlook Point, 12998 > 13005
- UN 12990, 12990 > 13003
- UN 12977, 12977 > 13002
- Peak R, 12995 > 13000

We lose 13 to newfound prominence values.
- Lightning Pyramid, 302 > 283
- Wood Mountain, 320 > 295
- Milwaukee Peak, 302 > 297
- UN 13510, 610 > 276
- Mount Rhoda, 302 > 297
- UN 13401, 301 > 296
- Cinnamon Mountain, 308 > 293
- Mount Lady Washington, 301 > 279
- Lenawee Mountain, 344 > 286
- Window Peak, 300 > 285
- UN 13123, 303 > 295
- Peak Twelve, 320 > 284
- Lomo Liso Mountain, 308 > 292

1 13er is demoted to a 12er.
- UN 13010, 13010 > 12992

Chiquita is still pending. Anything besides that that could shake the list up further?
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by JDG7 »

thank you for this work, wren
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Re: *PSA* - Ranked Lists Changing based off LiDAR Analysis

Post by bdloftin77 »

That matches what I see so far, Wren.

Here's some in the LoJ database that are almost soft-ranked. A few of these could end up being ranked.

I just looked at Mt. Maxwell, and it's actually ranked by 5 feet! The saddle had a spurious contour. I'm submitting this to John.

John's putting together a list of Colorado peaks that aren't in LoJ that have >240' of prominence. There could definitely be some new 13ers hidden here.

Also, of 13ers that have >320' of prominence that haven't been analyzed, there's definitely the possibility of some map errors causing some to be demoted, though this is less likely than the "error range" ones at between 300' and 320' that have already been looked at.
Colorado Almost Soft-Ranked 13ers
Colorado Almost Soft-Ranked 13ers
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