LiDAR - Pennsylvania HP (and other state high points)

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bdloftin77
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LiDAR - Pennsylvania HP (and other state high points)

Post by bdloftin77 »

LoJ Announcement
LoJ Announcement
PA State HP.png (48.22 KiB) Viewed 1566 times
Summary:

I've found class 2 (ground) points a foot higher than Pennsylvania's traditionally accepted high point, the top of a ~5' boulder. Since these are class 2 only, it's likely that there are boulders in these areas that are a few, if not several feet higher than the traditional high point. See links below:

New PA high point (highest class 2 returns): https://listsofjohn.com/peak/218278
Notes: https://listsofjohn.com/lidarnotes?id=218278

Old PA high point (class 1 return on traditionally accepted boulder): https://listsofjohn.com/peak/17861
Notes: https://listsofjohn.com/lidarnotes?id=17861

Background:

I've been taking a look at some state high points recently, especially ones with lidar coverage and that have competing contours. No surprises until I came to the Pennsylvania high point, Mt. Davis. John Kirk, Andy Hatzos (Andy Martin's friend), and I agree that the traditional high point is on top of a boulder ~5' above the ground, with a class 1 lidar return reading at 3212.73 feet. Looking else where though, I came across class 2 returns (ground only - not including boulders, trees, etc) that were above 3213 feet, some even almost 3214 feet.

Areas with class 2 returns over 3213':
39.783126,-79.178375,3213.45 (four returns, highest shown)
39.783179,-79.17820,3213.19 (four returns, highest shown)
39.783520,-79.177894,3213.55 (six returns, highest shown)
39.783648,-79.177709,3213.71 (seven returns, highest shown) (~900 ft from old HP)
39.783773,-79.177766,3213.25 (two returns, highest shown)
39.798385,-79.171250,3213.81 (11 returns in 3 clusters, highest shown -- 2 returns tie for highest) (0.9 mi from old HP)

John and I agreed on the traditional high point location and elevation, and he also agreed with the other findings. John notified Any Martin, who notified several others - one of whom (Andy Hatzos) responded with the email below:
Last edited by bdloftin77 on Mon Jun 13, 2022 2:33 pm, edited 2 times in total.
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bdloftin77
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Re: LiDAR - Pennsylvania HP (and other state high points)

Post by bdloftin77 »

Hi all,

I had time to look at the data last night, so I wanted to share what I found. The short version is that I still agree with the assessment that has been put together.

Three images are attached, all created using the the DEM from the 2019 LiDAR data. These aren't geo-referenced or anything, just quick and dirty output for the sake of illustration.

Image #1 (10ft contours)

This is a general overview of the entire site. There are two areas on Mount Davis that exceed 3200 feet, and from there, I've broken it down into three separate "clusters" of areas of interest.

The southern 3200-ft contour is significantly larger than the northern one.
Image 1
Image 1
Image 1.jpg (37.17 KiB) Viewed 1565 times
Image #2 (2ft contours)

The "southern cluster" is a fairly large area that includes the spot that John and Ben identified 900 feet SW of the main Mount Davis location. Within this cluster, I looked at the LiDAR ground return point data, and identified five separate sub-clusters where there were several ground returns in the 3212-3213 foot range (and a few above 3213 feet). These coordinates are approximately in the middle of those five sub-clusters:

39.78300, -79.17823
39.78311, -79.17837
39.78318, -79.17820
39.78352, -79.17788
39.78365, -79.17771 (this is the one originally listed by Ben)

The "middle cluster" is the area that includes the accepted Mount Davis boulder, and is very close to the observation tower. There are two sub-clusters of ground returns in the 3210-3211 foot range, both of which were identified in Ben's first message:
39.78598, -79.17662
39.78608, -79.17665

I also agree that the boulder location (39.78599, -79.17676) is nestled within an area of ground returns that are about 3207 feet.
Image 2
Image 2
Image 2.jpg (209.92 KiB) Viewed 1565 times
Image #3 (2ft contours)

The high point identified in Ben's first message (39.79839, -79.17125) is dead-on with what I'm seeing. It's an isolated raised area at the northern end of a larger 3200-ft area that is sort of shaped like an inverted triangle. This area is coincident with a sub-cluster of several ground returns in the 3212-3214 foot range. The terrain here looks considerably steeper than at the "accepted" Mount Davis HP location!

One thing I should note is that there are some chunks of empty space in this general area when plotting out the ground returns, suggesting some spots the LiDAR didn't catch (or at least didn't catch as a ground return). So that means the DEM in this area may be imperfect.

I did compare this area to the 2007 data as well. The two sources are in general agreement, though not perfectly. Interestingly, the 2007 data suggested some high areas further south in the triangle, but the 2019 data actually does have plenty of ground returns in those areas, all of which are considerably lower than the sharp rise at the north end of the triangle.
Image 3
Image 3
Image 3.jpg (152.38 KiB) Viewed 1565 times
------------------------------------------

In my opinion, we have plenty of enough evidence to suggest that the "accepted" Pennsylvania High Point boulder is not actually the highest point in the state. I also think the evidence suggests the highest spot in the northern cluster is the most likely new HP. However, the southern cluster is really really close, based solely on ground return data -- and actually has a larger surface area that exceeds 3212 feet. So really, any boulders in any of those spots could tip the scale from one to the other. And given the weird terrain and vegetation, the LiDAR is probably not 100% perfect!

I do think a site visit to all these new spots is going to be a key part of this exercise, and I'll be really interested to see what those spots are like. Hopefully not a miserable bushwhack...

My conclusions:

1) The highest point in the northern cluster is the likely PA HP.
2) The southern cluster (including my five identified sub-clusters) is also in contention and should be investigated.
3) The area near the tower, including the accepted boulder, is not likely to be the actual HP.

Thanks,
--Andy H
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bdloftin77
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Re: LiDAR - Pennsylvania HP (and other state high points)

Post by bdloftin77 »

Here are some pictures of the traditional Pennsylvania high point. Class 2 (ground only) returns elsewhere are about a foot higher than this point. A boulder elsewhere near those ground returns is likely the new Pennsylvania high point.

I'll let you know if I hear any more news from field visits to those candidate areas.
Traditional Boulder
Traditional Boulder
Traditional Boulder 1.jpg (313.25 KiB) Viewed 1549 times
Traditional Boulder
Traditional Boulder
Traditional Boulder 2.jpg (287.48 KiB) Viewed 1549 times
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