How to correctly measure HI

I suggested this type of feature 7 or years ago after I was introduced to my first use of a Leica TC303 with laser plumet and reflectorless EDM capabilities. I figured if it could do a distance shot through the main gun site, why the same distance (HI) shot through the plumet laser?

I haven't measured H I in years. It's always zero.

Stick ruler - works every time.

I dont think that there is anything more accurate than the Leica height meter.

Same here. 3d free stationing to the rescue.

That would be a great feature to have.

The way I do it when accurate HI's are needed is to always measure the HI for the gun (Trimble S6) to the bottom notch. I can do this to ±1 mm. The DC corrects that to true vertical to the scope height. All of my prisms/adapters are the same (seco mini). The prsim is 0.050 m above the adapter, and the adapters are 0.033 m. The S6 (and Wild T2, Zeiss S10, as well as other instruments) is 0.196 m above the tribrach plate, and the prism is 0.083 m above the plate. So, I can get accurate HI's and HT's to 1 mm.

> How about Reflectorless HI measurement?
How about a Disto coupled with some sort of height hook fitting.

> That would be a great feature to have.
>
> The way I do it when accurate HI's are needed is to always measure the HI for the gun (Trimble S6) to the bottom notch. I can do this to ±1 mm. The DC corrects that to true vertical to the scope height. All of my prisms/adapters are the same (seco mini). The prsim is 0.050 m above the adapter, and the adapters are 0.033 m. The S6 (and Wild T2, Zeiss S10, as well as other instruments) is 0.196 m above the tribrach plate, and the prism is 0.083 m above the plate. So, I can get accurate HI's and HT's to 1 mm.

:good:

Bottom Notch on Trimble is how I do it.

Ralph

me too.

I used to take the battery out of the Leica 1200 series because they have stuff in the way of getting an accurate measurement on both sides.

Leica has a tendency to over complicate a simple problem. Just make it so you can use any pocket tape to the bottom corner of the instrument (like GPS has been doing for over 20 years). No we have to invent this goofy cheap plastic hook thingy which only measures in meters (and the software can't convert to feet, sheesh). But I'm not bitter about it.

:bad:

A height stick or tape measure can do the job, unless you want to be really accurate.

At 1.5m HI, reading 10cm from the axis of the instrument, you'll actually read 1.503m.

> > At 1.5m HI, reading 10cm from the axis of the instrument, you'll actually read 1.503m.

Thanks for this easy to remember tip.

can some draw a sketch?

I am hard of thinking and I would appreciate a sketch to see what folks are taling about.

thanks for your help

can some draw a sketch?

The S6 has a notch on the bottom corner on both sides of the instrument. If you use Trimble's software then you can tell it the HI is measured to the "bottom notch" and it will calculate the true height to the trunion axis. It also has a mark at the trunion axis for normal HI measurement if you use non-Trimble software.

The notch is visible here:

Leica has at least a couple of different versions of the height tape. The C10 scanner comes with a cheap looking plastic thing which hooks onto the post of the tribrach to which you hook a vertical height tape which reads in meters (only) to the center (I think). They also make one which is a little more robust that fits into the cylindrical hole in Leica tribrachs then you pull the tape down.

The Trimble solution is a lot simpler and you don't need a special purpose tape that you have to get down on your hands and knees to operate.

can some draw a sketch?

The C10/TS15 one is the same and measures the vertical distance (if you check the tape against a normal tape 1m != 1m)

The other one you're thinking about is the GPS height gauge and is awesome. Just don't use it on any other instrument.

can some draw a sketch?

Here you go Dave!

Ih= 0.158+[tex]sqrt{Hm^2+0.091^2}[/tex]

Ralph

can some draw a sketch?

I don't have the height stick (we were given the instrument by Caltrans) so I use a CM/FT pocket tape.

I see the radius of the instrument is 9.1cm.

can some draw a sketch?

> I don't have the height stick (we were given the instrument by Caltrans) so I use a CM/FT pocket tape.
>
> I see the radius of the instrument is 9.1cm.

I don't have a height stick either, I use a 6 foot ruler. Works pretty well measuring to the bottom notch and inputting it into the collector. I guess they add the formula in case you're not using a Trimble collector. On that note, I wonder if Survey Pro has that option.

Ralph

Correction

> Ih= 0.158+[tex]sqrt{Hm^2+0.091^2}[/tex]
>
>
>
> Ralph

The above equation should be a minus, so it should read like this:

[tex]Ih= 0.158+sqrt{Hm^2-0.091^2}[/tex]