Do you:
1. Calculate what the true HI is for your total station setup or or do you just accept the actual distance you measure to the center point on the side of the total station? I calculate what the correction is at my average HI,which is 0.03', so I always measure to the center point on the side of the total station and then subtract 0.03' in order to get my true HI.
2. Adjust for the wear on the tip of your rod and subtract appropriately from your graduated rod readings. For example I will adjust from a normal 5.11" low rod to 5.10' when my tip wears down some.
How do you handle this? I am thinking that if you do not follow this procedure then you likely have 0.04' worth of vertical errors floating around in your final vertical solutions at any given time.
Adjusting by 0.03' seems quite excessive.
If your measured HI is 5.50' and the offset from center is 0.40', then the adjusted HI would be 5.485'. That's only 0.015' adjustment, roughly half of what your suggesting.
And yes, it does help in the verticals.
Buttonpushers!
> Adjusting by 0.03' seems quite excessive.
> If your measured HI is 5.50' and the offset from center is 0.40', then the adjusted HI would be 5.485'. That's only 0.015' adjustment, roughly half of what your suggesting.
>
> And yes, it does help in the verticals.
Good point, however the Trimble 5603 is a wide body instrument, I need to check the actual width, was using 5.50' and a offset of 0.60'.
I can't even comment on this without using [banned] four letter words.!
Loyal
> I can't even comment on this without using [banned] four letter words.!
>
> Loyal
Please tell...
With the s6, you leashes the slant heighth to the measuring notch, input that into the ranger, then drop down the option to correct for true height. SWEET FEATURE! On the other issue, we don't use the pole and bipod for control. We turn to tripods with tribachs and prisms.
> the Trimble 5603 is a wide body instrument, I need to check the actual width, was using 5.50' and a offset of 0.60'.
The Geodimeter 600 series, which Trimble restyled only slightly and began selling it as the 5600 series, has a half-width of only 0.3'. So a slant height of 5.50' measured at the side cover dot translates to an HI of 5.492'.
I, too, mentally adjust the rod reading to account for tip wear. I've been meaning to add some shims so I don't have to do that, but I've been meaning to do it for about 5 years now.
Stinking Leica added nobs and stuff on both sides of the 1200 so it's tough to get an accurate measurement. On the 1100 series you could lay your tape right up against the side.
I do everything 3D, even Forest traverses which the other Surveyors think I'm crazy or weird but it's a 3D world so I think it's best to work in 3D and it gives more data for LS to play with.
I know that with trimble GPS units you can get a folding measuring rod that is calibrated to give you the corect reading. im not sure if the have one for total stations or not. You just have to make sure that you have the corect rod as each is meant to read a different offset, i.e. radius from center of the unit.
Sorry Boundary...
What I was going to say doesn't really matter a this point.
FIRST, I pretty much agree with your methodology and applaud your desire to minimize as many error sources as possible (or practical). I usually calculate the "true vertical" but IF your HI(s) are reasonably consistent, then I don't see a problem with your solution.
SECOND, what set me off last light, was the implication by some folks (not in this thread) that you were over-killing a trivial error source. I don't believe that ANY error source that is EASILY minimized, is trivial.
THIRD, too many “Land” Surveyors get caught up in this “expert measurers are bad” tripe that floats around. I had spent the better part of the afternoon yesterday mediating an argument between a young LSIT and an old (my generation) retired LS about what is and isn't “trivial.”
Basically the “old guy” contended that once you hit 1:5000, you're DONE, don't sweat the small stuff! Now obviously there ARE situations where 1:5000 might be good enough, but I believe [STRONGLY] that practicing GOOD procedures ALL THE TIME is the proper modus operandi for all surveys. Nobody EVER went back to rerun a survey that closed TOO GOOD!
Loyal
I always carry elevation, too, because it is a 3d world and you never know when you are going to need it.
I too will calculate the HI, why not, it's not that difficult. If I am really concerned about the elevation, I.E. construction staking, I will shoot a bench and conform my measurements to that.
Radar
Loyal
I throw around the term,"expert measurers" many times and it is intended to be those so-called surveyors who take the measurements without judgement, and put them on the ground.
The way I look at it is, it takes a good expert measurement by the survey technician, and when used by the land surveyor without thought, he also is the survey technician. The land surveyor knows what to do with the expert measurements.
Obviously, if the land surveyor is making the expert measurements and uses them without thought and judgement, then he is acting like the expert technician.
Keith
Sorry Boundary...
> THIRD, too many “Land” Surveyors get caught up in this “expert measurers are bad” tripe that floats around.
Amen
It often seems that many read Mumford's admonishment "It is far more important to have a somewhat faulty measurement of the spot where the line truly exists than it is to have an extremely accurate measurement of the place where the line does not exist at all." as an unquestionable dualism and fail to see another, far superior, option; an accurate measurement where the line truly exist.
Keith
I wasn't picking on you in the above post/rant. I know very well what you MEAN when you use the term, and for the most part, I think that you and I are on the same page.
You and I have both run random lines through the woods with a transit & tape, and come back and pulled “offsets” over to the “true” to set various corners. We both used reasonable care in making those measurements, but it's unlikely that a modern GPS/Total Station survey would return EXACTLY the same solution. IT DON'T MATTER, the corner is where it IS!
What makes me NUTS, is the folks with a gazillion dollars of high-tech gear, who don't own a thermometer, barometer, or worse yet...a SHOVEL! And of course those who won't ACCEPT an extant monument if it isn't EXACTLY where THEIR measurements tell them it SHOULD be.
Loyal
Sorry Boundary...
Darned tooting Loyal.
Good methodology yields good results. If you know of ANY possible error then you compensate (calculate it out) for it.
From PPM's to tape pulls. Good methods have always been a part of my measurements.
We should be the expert measurers. That doesn't mean we ignore the other evidence just that we rule out all the errors that can be corrected. We can still use a corner that is 100' away from a calculation because of other evidence.
I see no conflict in trying to reduce errors and in making a decision based on harmony.
This is a real no brainer to me. If you know you have an offset then calculate for it and go on down the road. I don't ignore any error that I can negate.
> I always carry elevation, too, because it is a 3d world and you never know when you are going to need it.
>
> I too will calculate the HI, why not, it's not that difficult. If I am really concerned about the elevation, I.E. construction staking, I will shoot a bench and conform my measurements to that.
>
> Radar
Radar, I agree with this methodology. If you are shooting a bench and adjusting everything to that, I have found works better than getting a perfect HI measure-up. This is standard procedure w/Trimble and Leica robots because I've seen only using the measure-up to be unreliable for carrying elevations.
Loyal
I know we are on the same page and I was just explaining my view on the so-called surveyors who practice expert measuring only.
The surveyor has to make the judgement on how the these measurements are to be used, and some simply don't.
I am not impressed with the arguments on how they can measure the width of my finger nail!
Keith
Your statement, And of course those who won't ACCEPT an extant monument if it isn't EXACTLY where THEIR measurements tell them it SHOULD be.
That is exactly what I am talking about.
Dave
It's been a while since I've used a Leica but when I did we had "height hook" that had a tape built into a hook that fit into the side of the tribrach. This allowed us to pull a verical height directly from the point. The small tapes were a little brittle and had to be replaced occasionally but the direct measurement was worth the cost.
Andy
Dave
Gene had one of those, pretty cool. I think all of the Leica equipment is designed to be the same height above the tribrach. Naturally my employers (so far) never purchase the entire system, just the total station.
