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I would consider stripping his name and ls number from the report you posted out of general courtesy.
I would not appreciate being put on blast with what was probably an internal document.
This might help, with my CAD software, it is set to a scale factor of 1.0000
And when I pick a building corner etc.. from CAD it matches the blueprint coordinates exactly
I did a quick calculation at that location. You’re using the wrong system, you’re confused by the scale factor of 1. The grid distance of two state plane points 950.00′ apart should measure 950.14′ on the ground.
I don’t know that software that you posted a screen shot of, but I’m assuming the 1 scale factor means no adjustments are applied to state plane.
I’m not sure about your horizontal but you have a vertical issue also. You shot between 48-45, 47-46, and 47-48. With the trig elevations looking fine 0.02′ being the largest difference. But when you staked out 47 you got a fill of 0.18′. Not sure what the occupied point was for this stake out shot but the elevation of 47 agreed with both 46 and 48 and thus 45 previously. It shouldn’t miss on this stake out shot unless you were using a control point not mentioned yet to stake it from.
The stakeout was a GPS shot on their control point, which I forgot I did, until digging up the records
rpls.com
Control Bust - Strictly Surveying - RPLS.com
I'm doing construction layout on two sites, and on one of the sites the PLS Company came out and set 4 control points and sent me the N,E,H... Nevada East state
Is 0.18′ an expected miss for your GPS equipment? Using the equipment I’m familiar with, missing that far in elevation is an indication of something wrong.
So are you implying the TS is not in the correct scale factor? I was taught to always keep the TS at a scale of 1, so when things are field measured with a steel tape things are going to line up.
I understand state plan is a grid system and a TS at a scale of 1 is ground. That’s why I do a grid-to-ground conversion with GPS.
Is 0.18′ an expected miss for your GPS equipment? Using the equipment I’m familiar with, missing that far in elevation is an indication of something wrong.
No, I have a Leica GS18, I would have to stake that point out again to be sure, as of now Im trying to get my horizontal dialed in first.
When you’re shooting ground with a TS is your scale factor always 1.0000 correct? I’m not trying to shoot to the grid if I were then I would change the scale factor.
Yes, that’s what I’m saying.
950.15′ x combined scale factor of .999853 = 950.01′.
That’s what you’re seeing isn’t it?
Here is my combined scale factor for this project from my GNSS
So if I change the scale factor on the gun to 0.999853 I should line up with survey control?
For example- if I shoot in the grid lines for the project at that scale factor, then a tape check would not measure up. So our the surveyors using a grid scale and switching to the scale of 1.0000 to shoot in the grid lines? I had them shoot in the grid since I could not line up with their control. And the carpenters taped checked the points and said they were good, within 0.01′
Sorry, but the surveyors won’t give me any correct info.
My process would be to occupy the control with state plane projected into my field file in the DC. When the points are located the DC correctly applies all the transformations as you’re working. The TS is never tweaked. I want that data “clean”.
As an aside it’s difficult to understand why a project in Las Vegas would be surveyed to a projection 3000′ some feet below ground. With the size of buildings and facilities I’ve seen there I would think actual ground distances would be the thing to do.
Grid is grid and ground is ground. Mixing the two causes problems.
On the data sheet for the provided control what does “Ground scale factor = 1” mean? State Plane Coordinates are on the grid which is not at ground level except at those locations where the grid exactly coincides with the ground, which are the exception not the rule.
“When you’re shooting ground with a TS is your scale factor always 1.0000 correct?” A TS scale factor of 1.00 is for measuring distances at ground level. If you’re want to measure ground distances corresponding to grid distances, your TS scale factor should be 1/CF.
In your area, the grid scale factor is 0.999929027. Using 1675 ft as the project elevation with a geoid height of -92.5 ft, the elevation factor is 0.99992423 making the CF 0.999853262. If you want to lay out a 950.00 ft grid distance, you would measure out 950.00 x (1/0.99984833) = 950.139 ground distance which is right about the 0.015 difference you started with.
Your GNSS Local Transformation parameters show CF = 1.000146512. That’s the inverse of the CF: 1/CF = 1/0.99984833 = 1.00014676 which is very close to the GNSS parameter.
If you want to lay out a 950.00 ft grid distance, you would measure out 950.00 x (1/0.99984833) = 950.139 ground distance which is right about the 0.015 difference you started with.
The question is….why would someone publish control in grid coordinates in the first place?
I’ll bet a year’s salary that the design planset does not say “All design dimensions are in grid. Convert to ground distances using combined scale factor noted on control sheet.”
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman- This reply was modified 3 months, 2 weeks ago by rover83.
I want to be able to measure the ground distance with a TS at a scale of 1.00000 so they are true ground distance. The surveyors shot in the control points with a TS and GPS, and All I know is my TS with a scale of 1.000 doesn’t match their points.
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