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Measuring HI

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(@dougie)
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John Giles, post: 335423, member: 57 wrote: As long as I don't adjust the rod up any, the data collector sees the information as though the TS and Prism are at the same height and the rod and legs are underground to the DC.

So when you boot the rod; you tell the DC the difference? Up or down?

 
Posted : September 7, 2015 9:43 am
(@john-giles)
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RADAR, post: 335434, member: 413 wrote: So when you boot the rod; you tell the DC the difference? Up or down?

Yep.

 
Posted : September 7, 2015 9:51 am
(@mike-marks)
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Measuring HI was easy when using Kern forced centering tripods, just read the rod:

 
Posted : September 7, 2015 10:28 am
(@christ-lambrecht)
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Dave Karoly, post: 335355, member: 94 wrote: I measure to the bottom notch on the S6.

using this 2m. piece

 
Posted : September 7, 2015 10:45 am
(@brad-ott)
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Mike Marks, post: 335442, member: 1108 wrote: Measuring HI was easy when using Kern forced centering tripods, just read the rod:

snappy dresser

 
Posted : September 7, 2015 10:54 am
(@holy-cow)
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For most basic boundary surveys there is no real necessity to work in 3D. This message brought to you by The Flat Earth Society.

Save the HI worries for topos. Remember.....all things are relative.

 
Posted : September 7, 2015 5:21 pm
(@john-giles)
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I've worked on dam and road projects with this method. It works. I think I just can't get it on paper as good as I can on the ground. If you've never done it like this you'd have to see it to believe it I guess. I never measure HI and only rarely (when I have to raise the rod) measure HR.

I never do this on boundary projects. As Holy said I don't need to work in 3D on basic boundary. Unless the previous surveyor used slope. Which has happened on occasion but rarely.

I did a boundary where I had to survey 100 Acres and carry elevations all the way around it because of the take area for the pool area of a dam. I started in a hollow, traversed around the lake topoing it. Then up a steep hill and back down the other side. I did miss my a tenth or so (can't remember exactly) in the end but we had at least 40 traverses that I carried the BM on. Would have been easier in the winter. The best part was how I got the BM to begin with. I went to the dam. shot in the BM (brass disk) and shot in the top of the water. Drove three miles upstream and shot in the top of the water. I then checked to a BM (a railroad spike in a tree off road plans) at a new bridge and fit within a few hundredths so I new I was good to go. water seeks it's own level. My former boss taught me that one. I was going to traverse all that way but he said why do that when you can just shoot in the water. Holy heck why didn't I think of that.

 
Posted : September 7, 2015 5:49 pm
(@holy-cow)
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Still water only. No flow, no wind.

 
Posted : September 7, 2015 7:57 pm
(@mightymoe)
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John Giles, post: 335465, member: 57 wrote: I've worked on dam and road projects with this method. It works. I think I just can't get it on paper as good as I can on the ground. If you've never done it like this you'd have to see it to believe it I guess. I never measure HI and only rarely (when I have to raise the rod) measure HR.

I never do this on boundary projects. As Holy said I don't need to work in 3D on basic boundary. Unless the previous surveyor used slope. Which has happened on occasion but rarely.

I did a boundary where I had to survey 100 Acres and carry elevations all the way around it because of the take area for the pool area of a dam. I started in a hollow, traversed around the lake topoing it. Then up a steep hill and back down the other side. I did miss my a tenth or so (can't remember exactly) in the end but we had at least 40 traverses that I carried the BM on. Would have been easier in the winter. The best part was how I got the BM to begin with. I went to the dam. shot in the BM (brass disk) and shot in the top of the water. Drove three miles upstream and shot in the top of the water. I then checked to a BM (a railroad spike in a tree off road plans) at a new bridge and fit within a few hundredths so I new I was good to go. water seeks it's own level. My former boss taught me that one. I was going to traverse all that way but he said why do that when you can just shoot in the water. Holy heck why didn't I think of that.

 
Posted : September 8, 2015 5:20 am
(@mightymoe)
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John Giles, post: 335465, member: 57 wrote: I've worked on dam and road projects with this method. It works. I think I just can't get it on paper as good as I can on the ground. If you've never done it like this you'd have to see it to believe it I guess. I never measure HI and only rarely (when I have to raise the rod) measure HR.

I never do this on boundary projects. As Holy said I don't need to work in 3D on basic boundary. Unless the previous surveyor used slope. Which has happened on occasion but rarely.

I did a boundary where I had to survey 100 Acres and carry elevations all the way around it because of the take area for the pool area of a dam. I started in a hollow, traversed around the lake topoing it. Then up a steep hill and back down the other side. I did miss my a tenth or so (can't remember exactly) in the end but we had at least 40 traverses that I carried the BM on. Would have been easier in the winter. The best part was how I got the BM to begin with. I went to the dam. shot in the BM (brass disk) and shot in the top of the water. Drove three miles upstream and shot in the top of the water. I then checked to a BM (a railroad spike in a tree off road plans) at a new bridge and fit within a few hundredths so I new I was good to go. water seeks it's own level. My former boss taught me that one. I was going to traverse all that way but he said why do that when you can just shoot in the water. Holy heck why didn't I think of that.

Your method is what I did often back in the day, now it's not so useful with our new equipment.

We always called it the "grade rod" method. Really simplified staking.

But with the robot it's not really as simple as it was, heck I don't really know the HI cause I measure to the measure point and that isn't the HI.

 
Posted : September 8, 2015 5:25 am
(@dave-karoly)
Posts: 12001
 

Holy Cow, post: 335462, member: 50 wrote: For most basic boundary surveys there is no real necessity to work in 3D. This message brought to you by The Flat Earth Society.

Save the HI worries for topos. Remember.....all things are relative.

I always carry verticals because I almost always use static GNSS observations and adjust the whole thing simultaneously which requires three dimensional measurements since GNSS is a three dimensional system.

It really isn't that difficult to do.

 
Posted : September 8, 2015 5:35 am
(@dave-karoly)
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MightyMoe, post: 335496, member: 700 wrote: Your method is what I did often back in the day, now it's not so useful with our new equipment.

We always called it the "grade rod" method. Really simplified staking.

But with the robot it's not really as simple as it was, heck I don't really know the HI cause I measure to the measure point and that isn't the HI.

I made a blunder on a bottom notch measure up. I determined it was 0.05' because I know the difference between the target height and the bottom notch on the same tripod setup. I found the Trimble formula (and constants) for converting bottom notch to H.I. by googling a little bit.

The stupid thing was it told me I had a 0.08' vertical bust when I was setting up out there but I just plowed ahead. I had a bad cold that day and felt like spit so I blame it on that. I knew I had a problem so I fixed it later. I had redundant ties through another control point so I confirmed the blunder.

 
Posted : September 8, 2015 5:39 am
(@zoidberg)
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I believe the Laser Scanner from Topcon uses a red laser to measure the HI by itself. Seems it should be available in total stations...

 
Posted : September 8, 2015 10:29 am
(@bill93)
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Holy Cow, post: 335482, member: 50 wrote: Still water only. No flow, no wind.

In a large body of water, even when the wind stops you may still have seiche changing the height of the water for a long time.
See
https://surveyorconnect.com/threads/trick-for-leveling-from-water-surface.181038/
or the last few posts of this thread
https://surveyorconnect.com/threads/ring-ring-there-is-a-problem.287531/

 
Posted : September 8, 2015 10:45 am
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