For the 80th posting to this thread I'd like to crow about the low-distortion zones system in Oregon called the Oregon Coordinate Reference System (OCRS). These scaling issues just don't exist when using the OCRS. Yet too many people insist on continuing to F' around with scaling state plane. Arrrgh!
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Amen. Go low distortion or go home.
Custom projections just aren't a problem any more with industry-standard sofware.
The thumbs up option is only available when viewing from the activity thread. A very odd structure indeed.
It's extremely common that grid to ground coordinates are not truncated in every area we work. Haven't ran into any issues yet. The only issues we run into is when the original surveyor can't adequately explain their project datum in a clear and efficient manner....which is why we try very hard to not ever be in that position.
Just to be clear about prism constants using a Leica TS......you wrote that you "checked the prism constant" but if you are using a Leica prism and select it from the list then the prism constant is set for you, you cannot change it. If you use any other non-Leica prism you must create a custom prism in the list with the correct constant for that prism. If you use a standard non-Leica round 30mm prism and select the Leica standard round prism from the list you will measure 0.10' long (too much) on every shot because the Leica prism is preset at 0mm.
Edit: I just saw your post on "My New Setup" and that looks like a non-Leica prism so I would check some short TS shots with a tape.
More exactly, the number is 34.4 mm = 0.113 ft, not 0.1 ft.
If you use a non Leica prism and tell the instrument it is a similar Leica, the difference should be minor.
If you tell the Leica instrument it is a -30 mm prism, then yes, you are off a bunch.
So true.
You are correct. I set 2 points 10.00' apart on my level driveway. Used my Leica TS15 and a Leica round prism on a tripod with a tribrach and measured 10.000'. Popped off the Leica prism and set a Sokkia round 0.30mm prism and measured 9.991' using the same Leica round prism selection from the list. But I do not know why the Sokkia measured short. The Leica is -34.4mm and the Sokkia is -30.0mm. It should have measured 10.014' right? No?
Edit: Thought about it some more and the Leica applied a -34.4mm constant to a 30mm shot making it 0.014' shorter at 9.99'.
So to add some Closure to this bust. I called the survey company out on the bust of 0.15' on the control.
They came out reshot it and said yes there is a problem, (I watched as they did a resection ) Then they came out the next day with a different gun. Attached is a text from the Manager
They sent me the new control, I set up on the new control and did my backsight, and was was .006' at a 930' shot. and checked in on another control and was good there also. Then went to all the batter boards that they set grid lines on and I was 0.01 or better on every grid line shot. This is on a scale factor of 1.00000 and Yes I have a Leica round a Leica 360 prism and one SECO -30mm. The SECO is the only prism I have to make in the prism selection tree. You put in the -30mm in the absolute section and the software calcs out what it needs to be.
Damn. That text from the manager...wow. It ain't as if SPCS is new or anything.
Attached is a PDF from Carlson about NAD83 State Plane with a total station and more info, just something I found when doing hours of research trying to figure this out. I am not a PLS, I do construction layout and this project happens to be in the State Plan System.
Nice job on ‘sticking to your guns’ and calling them out. You potentially saved their butts some $.
@CV-Nevada Thank you!
I hate state plane but not because I lack understanding. I hate that the scale factors differ from 1.000 by enough to be a real problem that people attempt to address with this scaling to ground BS.
My state, Oregon, has a system of low distortion projections which everyone should use, IMO, because it eliminates the need for scaling. Nevertheless, most do not, inexplicably. And I really, really hate that.
@Norman_Oklahoma I know Illinois is about to go from 3 zones to like 30 in the near future. I thought Missouri was about to do the same thing. Just for the reasons you described.
Many states are doing so with the NATRF2022 roll out.
I worked on a project that was using a scale factor for everything. It was a large tunnel and road and we couldn't use CSF 1.000000, or else there would be issues. I still remember the scale factor, 0.999954, because we'd do some monitoring and we'd have to put in the scale factor on each new job.
You asked earlier about zeroing the gun, which I assume means setting a zero bearing on a known backsight. If you're using the known backsight setup method, it won't work because the software will calculate and use the bearing between the two known points, your setup point and the backsight. If you want to set a zero bearing, you should be using the set orientation method instead. Out of curiosity, why would you need to do this? When I use the set orientation setup method, I'm working on a new project where I'm picking up known points that I'll later swing into their correct place. On a construction project, where control is established, I would generally resect, or use known backsight, if using ground control points.