> use slant heights at the gun and at your tripod mounted BS and fs. you can estimate to the .005 and correct up. works pretty good. you'll see it come in when you do your least squares adjustments.
Yes, exactly. Just measure the eccentricity of the mark on the side of the instrument, i.e. how far it is off the vertical axis of the instrument, and correct the slant measurement made with a tape. If you're in error by more than 2mm, you need to rethink your lifestyle.
Since most HI's will fall within a narrow range, one should expect to find that simply subtracting a constant from the slant height gives the measurement corrected to the tilting axis of the instrument, and all with a simple pocket tape. If you need the HI to be measured better than an s.e. of +/- 1mm, a different method should be used.
I use the Leica measuring doodad, especially if I'm after precise heights.
If I am just using a tape measure, on a quick and dirty station setup, then I know that for my usual height of instrument, the tape will read about 3mm long (1.6m up, by 0.1m across = 1.603m).
> I use the Leica measuring doodad, especially if I'm after precise heights.
>
> If I am just using a tape measure, on a quick and dirty station setup, then I know that for my usual height of instrument, the tape will read about 3mm long (1.6m up, by 0.1m across = 1.603m).
How does the HI via slant height measurement by tape compare to that derived by measurement via the Proprietary Swiss Method? Do they check within about 1mm?
Wow. It's been a long time since I did that check.
Yes. I'm pretty sure that's the case.
Scott Zelenack had a Leica HI measuring device with a table for temperature adjustment. Overkill, I think.
I think Carlson SurveCE changes the elevation of the OP when you run remote elevation.
I use the Leica tape for all of my work. It is just as simple as using a regular tape so why not save a little of my error budget for things I can not control. If you use their prism post and glass the tape can works with your BS and FS as well. I have even done the math on the ARP/HI separation so I can use it with our GNSS tri-pod setups. The tape even has a standard graduation so I can use it to measure offset and such.
Yes, I do it that way... but usually only if I forget to measure up.
Geodimeter 650 program #21 I think this robot is nearly 20 years old, so this isn't new software by any means.
When you move the instrument up to the next traverse point and backsight, you can get the real elevation of the starting point. It's a good check, and I find that usually my measure-ups are pretty good.
What kind of work are you doing whereas you require elevations more accurate than a few hundreths? I guess if your doing structural work, this would be worth giving some thought, otherwise...
Measure up, subtract 0.005 to 0.01 due to slant, done.
Has always given me good results.
-V
How much "error" do you think you are going to have in measuring a 5.5' H.I.?
I can't see ever having more than 0.02' - if you read the tape 0.01' low on a slant measurement you should always be within 0.01' of the vertical. That is close enough for me...
:good:
Thanks for all the answers - I think I was having a bad day with a stiff breeze blowing the tape around...
A surveyor in Hungary suggested a feature for every total station by introducing a hole in alidade to give way to a reflectorless shot directly from the gun itself. 😛
Horizon (Singapore) announced last two years that they found a new way to accurately measure HI. I don't know how it works but to my knowledge it is more of an optical application.
The thing that always gets me is reading the inch side of the tape rather than the decimal side, giving a mysterious +/- 0.06' when it happened. This was the frequent-enough personal blunder that lead me to the HI=0.00 resection method. If it's always zero, there's never a chance for a misreading.
> > I use the Leica measuring doodad, especially if I'm after precise heights.
> >
> > If I am just using a tape measure, on a quick and dirty station setup, then I know that for my usual height of instrument, the tape will read about 3mm long (1.6m up, by 0.1m across = 1.603m).
>
> How does the HI via slant height measurement by tape compare to that derived by measurement via the Proprietary Swiss Method? Do they check within about 1mm?
1. Is "slant height measurement" referring to the fact that you can't measure vertically directly from the side of the total station where the index mark is?
2. What the heck is the Proprietary Swiss Method?
I made a little jig out of a triangular piece of plexiglas, 3 adjustable legs and a fish-eye level bubble. One leg is a bit longer than the other two and graduated.
Set the thing up with the longer leg on the point level it up and read the number at the top of the glass; measure to the point on the side of the gun or target; add the 2 numbers together and voila! you have an accurate HI.
Dougie
ditto. BM rules...
