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# Geodetic Correction Formulae

Hi all

whats are the Formulae for

1. reduction to ellipsoid correction

2. Line scale error coreection

using final stations heights to compute

Any help would be great

Cheers

Mat

This Content Originally Published by a land surveyor to Land Surveyors United Network

Views: 373

### Replies to This Discussion

Hi Mat,

Is this what, you are looking for. I am confused on your  ?  But look over it

I have a lot of Data on this subject.

This site has a lot of good info plus this. Go Thru Geodesy also.

Look under Corrections

http://aplitop.com/subidas/ayuda/en/MDT-Topografia/index.html#!reductionToEllipsoid

http://aplitop.com/subidas/ayuda/en/MDT-Topografia/index.html#!scaleFactorDueToHeight

http://www.esri.com/news/arcuser/0703/geoid1of3.html

Here from NOAA , I sent these 2 to Raymond Kinglsy on one of his Discussion.

But NOAA has a lot more on this subject at there site.

http://www.ngs.noaa.gov/GEOID/PRESENTATIONS/2007_02_24_CCPS/Roman_A...

Hi Mat,

Did I forget to tell you I added one on Geoid and MSL, there is also some more info on it.In the others. Thanks for the programs again i never seen these P to R or the R to P. I like it,very short, i like that. that is why i use mine so much. I will try them in some programs.

From PS reference handbook:

Orthometric correction:

Correction = −0.005288 sin2φ h Δφ arc1′

where: φ = Latitude at starting point h = Datum elevation in meters or feet at starting point Δφ = Change in latitude in minutes between the two points (+ in the direction of increasing latitude or towards the pole)

h ≈ H + N

where: h = Ellipsoid height N = Geiod undulation H = Orthometric height

hello.

you can find it at the end of your total station field user book.

at list at the leica´s field user book.

Exactly what are you correcting/adjusting? Anything I could say about formula would be redundant but the problem is somewhat different if you are computing surface distances/coordinates from a GPS survey than if you are transforming a tangent plane survey to grid (geodetic) coordinates.
According to Phil Stevenson of NGS, there is no direct connection between GPS coordinates & a tangent plane survey. Fortunately, there are some pretty good solutions to the problem. I am generally faced with the task of incorporating GPS control into a traditional theodolite survey. I usually work in heavily wooded areas with few good GPS sites. It is rare that I can survey anything with GPS alone. GPS coordinates are easy to deal with as they can be converted to Lat. or Long., grid or surface with simple conversion factors/ formulas. Incorporating tangent plane data can get a bit sticky. I believe most DOTs make adjustments at regular intervals over long distances.

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