Subject: [cohp] County High Pointing in all 50 states - Digest #145 From: "cohp@groups.io" Date: 9/6/2020, 6:14 AM To: oldadit@gmail.com cohp@groups.io Digest #145 Groups.io This is a digest for County High Pointing in all 50 states. View all your groups.io groups, and edit your subscriptions, here. Do not reply to this email. To reply to a message, click the Reply link under the message. Topics in this digest: . 1. Re: Delaware LiDAR Data? messages: . 1a.  Re: Delaware LiDAR Data? From: Andy Hatzos Date: Sat, 05 Sep 2020 17:05:30 MST Hi again, I had time tonight to go back and look at the data for Kent County DE. This is also using 2014 USGS Post-Sandy LiDAR data, and the overall quality of the data is quite good. First, I agree with Micah that if simply taking the data at face value, there is one point that is higher than the rest -- the point marked on Peakbagger as "Area 8 near Twin Eagle Farms." My read from the LiDAR DEM: 82.3 ft at N39.294290 W75.703129 The question, then, is how much of a margin of error do you have to allow? I found seven other points in the county that have elevations exceeding 81 feet (along with a few others that didn't pass the eye test and looked spurious or artificial). Here are those seven, arranged in order of elevation. 81.9 ft at N39.282044 W75.711466 81.5 ft at N39.292302 W75.702987 81.5 ft at N39.291248 W75.702385 81.3 ft at N39.281797 W75.711484 81.2 ft at N39.283077 W75.704410 81.2 ft at N39.168311 W75.689601 ~81 ft at N39.169111 W75.701423* * the last one is an odd case, because the maximum value is 82.7 feet, but there are obvious data quality issues resulting from thick vegetation along a treeline. I don't buy the 82.7, and I suspect the hill probably peaks out closer to 81.0, maybe 81.2 feet. We have a lot of good things working for us here -- the data quality is excellent, contamination from thick vegetation doesn't seem to be an issue (aside from the one spot mentioned above), and the slope of the terrain is very gradual. I'd normally use a bigger cutoff, but I think a one-foot cutoff is appropriate in this case. That would leave just five points to visit, all of which are part of the northern cluster near Twin Eagle Farms. These three are south of Holletts Corner Road: 82.3 ft at N39.294290 W75.703129 81.5 ft at N39.292302 W75.702987 81.5 ft at N39.291248 W75.702385 These two are on either side of Longridge Road: 81.9 ft at N39.282044 W75.711466 81.3 ft at N39.281797 W75.711484 That's just my opinion from the read of the DEM, obviously, and I understand if others may feel differently one way or the other. But going from 21 points to 5 points is actually a much better end result than I was expecting after my first glance at the data! Thanks, --Andy H View/Reply Online | Reply To Group | Reply To Sender | Mute Topic | Top ^ | New Topic Groups.io © 2020 Groups.io You are receiving this email because you are subscribed to cohp@groups.io via oldadit@gmail.com. You can unsubscribe here.