Vertical error

Shoot 4 points of known elevation from one setup. If they agree with each other then the issue may be in how you measure up during the setup process. I know nothing about the ES 62 but do you compensate for the slant distance when measuring up?

0.01' - 0.02' is pretty good, IMO. That's near the limit of accuracy you can expect from the method employed. The weak point is the measure ups.

If you are measuring them in the standard way, with the standard box tape, you are measuring an angled distance with an approximate 6" base, which will be about 0.015' longer than the true vertical distance., to a rather poorly defined mark on the side of the instrument. Plus, the tape can get bent a little in the effort, making the reading long. Then there is the matter of whether the point you are measuring to is the same point?ÿ the rod rests on when you shoot. It all adds up to the measure up being a very weak measurement.?ÿ

Posted by: @david3038

Ran 2500 feet today with 16 setups. 1250ƒ?? out and 1250ƒ?? back on the same points. Horizontal out .06 and vertical out .10.

With that error of closure for 16 setups, I would not even make any adjustments to the traverse stations. More work than derived benefits.

Posted by: @david3038

Ran 2500 feet today with 16 setups. 1250ƒ?? out and 1250ƒ?? back on the same points. Horizontal out .06 and vertical out .10

That works out to about 0.006 ft per setup, which is below the threshold of measure-up error.

So it's highly unlikely there is a systematic error, but if you really want to check that, test the instrument by shooting increasingly longer distances and check against a level run. A 0.01-0.02' error at ~160 feet (average distance of setup per above info) should increase to a tenth or so over one thousand feet, so it will be obvious.

I would not sweat that one bit.?ÿ

Itƒ??s a one word fix... Leica.?ÿ

@norman-oklahoma

I would second that. If you want to tighten up that vertical account for the slope on HI. Trimble has a bottom of notch measure for this is there similar on the Topcon?

@norman-oklahoma Agree. There is error in every measurement, and data is averaged/adjusted from different observations that never perfectly agree with each other.

@jt50

That's not accurate enough for your purposes? In my book that's as close to perfect as I would ever expect...

@totalsurv

The notch on the Trimble is a good low-tech approach to the problem. But even that notch is a molded plastic thing, not a sharply defined edge. Measuring it to better than +- half a hundredth is not realistic.?ÿ

I use a folding rule rather than a box tape for measure ups. I think it is slightly more accurate. Less likely to get bent by the wind. Doesn't rust when it gets wet.?ÿ?ÿ

Years ago, on the RPLS board Jesse (can't remember spelling of his last name) posted a very well written procedure for running very accurate levels without the measure up factor. If you want, I'll see if I can find it. Might help determine if measure ups are the problem.

@norman-oklahoma

The notch on my S6 is a well defined edge that can be measured to consistently. Back sight errors of 1-2mm usually.

If you run levels with a total station and you take a backsight and a forsight with the same rod and target, your measure up and your target height make no difference. You can call them both zero. It has to be in the gun or some other procedure. If I needed better than 0.006 / setup, I'd get a level.?ÿ

I think it was Scott Zelenek had a Wild measure up rod that included correction for temperature as well as slant.?ÿ

Posted by: @larry-best

True if you use a procedure like traditional leveling, but perhaps he is trying to carry vertical as part of a traverse? Thus setting the TS on the points for which elevations are computed?

@hooks

Just curious what you would consider repeatable vertical misclosure with a Leica TS over 2500'??ÿ The reason I ask is because it's been over a decade since I used Leica gear and it was rarely to carry elevations.?ÿ More of my work these days is 3D and I've been wondering if the green machines would make a noticeable difference?

I've been been getting similar results to the 0.1'/2500' vertical with a Trimble S7 but attributed most of this to using a measuring tape to the prisms.

@totalsurv

?ÿ

if I remember correctly, when you measure to the bottom notch on Trimble S instruments the slope distance is accounted for in the software.?ÿ

@eddycreek

You remembered correctly. Same thing when you're using an R10 as a base with its base extension and measure the bottom of the R10 lever extension.

Posted by: @stacy-carroll

kozlowski

Search that name and Trigonometric leveling

You should find some presentation material and a Youtube video

Posted by: @norman-oklahoma

0.01' - 0.02' is pretty good, IMO. That's near the limit of accuracy you can expect from the method employed. The weak point is the measure ups.

If you are measuring them in the standard way, with the standard box tape, you are measuring an angled distance with an approximate 6" base, which will be about 0.015' longer than the true vertical distance., to a rather poorly defined mark on the side of the instrument. Plus, the tape can get bent a little in the effort, making the reading long. Then there is the matter of whether the point you are measuring to is the same point?ÿ the rod rests on when you shoot. It all adds up to the measure up being a very weak measurement.?ÿ

Iƒ??m thinking this is the answer. This equipment has not been in service too long and Iƒ??m comparing it to past results with some older Topcon instruments that I no longer use because of incompatibility with our current data collectors. Went back to this job with a Leica TS07 that measures the Hi with a laser and was getting backsight errors on the adjusted traverse of less than .01.

?ÿ