Please do not over complicate this. Is there a program that will convert Lat/Lon/Ellip to
NAVD88 please?
All I need is the elevation in NAVD88. Thanks
> Please do not over complicate this. Is there a program that will convert Lat/Lon/Ellip to
> NAVD88 please?
>
> All I need is the elevation in NAVD88. Thanks
I like the way you ask for help and set the term and conditions......classic
lol
Topcon Tools
Topcon Link
Magnet Tools
Magnet Field
NGS has an online tool to calculate the geoid height by inputting the latitude and longitude. The orthometric height is easily converted using H=h-N where h is the ellipsoid height and N is the geoid height. Remember, add two negatives so if you have an elipsoid height of 100m and the geoid height is 39m it would equal 139m. 139m=100-(-39) is equal to 139m=100+39.
http://www.ngs.noaa.gov/cgi-bin/GEOID_STUFF/geoid12A_prompt1.prl
It doesnt say NAVD88 when I go there. I just need a simple program that when I put in lat/lon/ellip it then spits out "NAVD88" not GEOID (whatever they come up with next)!
It isn't that simple. First of all, what datum is the lat/long/ellipsoid height in? I makes a difference.
> Please do not over complicate this. Is there a program that will convert Lat/Lon/Ellip to
> NAVD88 please?
>
> All I need is the elevation in NAVD88. Thanks
CORPSCON is the old standby. There are pitfalls, lots of them. Among them is the need to load Geoid12A as a custom geoid. But you want simplicity over correctness.
If you are willing to sacrifice some of that simplicity check out Mark Silver's article in American Surveyor.
> It doesnt say NAVD88 when I go there. I just need a simple program that when I put in lat/lon/ellip it then spits out "NAVD88" not GEOID (whatever they come up with next)!
What the hell do you think the connection between ellipsoid height and NAVD88 orthometric height is exactly?
For an uncomplicated answer (ie don't bother me with details) you might try CORPSCON.
That article illustrates perfectly why you need to know what datum the lat/long/height is framed in.
Not just datum, but adjustment as well.
As near as I can tell specific Geoid models in the US are tied to specific adjustments of NAD83. This allows for substantial adjustments in ellipsoid heights without affecting orthometric heights.
For example in our area the HARN derived ellipsoid height for our office monument was 96.562m and the orthometric height (using Geoid99) was 122.828m. In 2005, using OPUS, (NAD83,CORS96) the ellipsoid height was 96.455m with an orthometric height (using Geoid03) was 122.481m. That's a difference of 0.107m in ellipsoid height, but only a 0.012m difference in orthometric height. In 2012, we did another lengthy observation of the office monument and determined an ellipsoid height of 96.450m and an orthometric height (using Geoid12A) of 122.823m.
Conclusion: it's important that the Geoid model matches the adjustment. It is possible to use a geoid model for an adjustment it doesn't relate to in order to produce reliable relative heights (fixing one control point), provided that the user understands that one or the other (ellipsoid or orthometric) will not be accurate.
I just need a simple program that when I put in lat/lon/ellip it then spits out "NAVD88" not GEOID (whatever they come up with next)!
What you want doesn't exist, but this will do the trick, its not a program but it does measure NAVD88 elevations;-)
Exactly
Where do you get the ones calibrated for NAVD88?
They use the super secret device to measure the Geoid slope:
+1:good:
You should also be aware of how accurate NGS thinks the geoid model in your area is - GEOID12A accuracy maps
UGH... I hate this place, but I keep coming back. Insanity?!
Use Corpscon from the USACE. Google it.
You could also add GEOID12A to your Topcon software. Read the help file or manual. Google it.
You should be using the GRS80 ellipsoid for your elevation calculations.
Yes, I've seen that map, it isn't very accurate according to the map in my area, but then I already knew it;-)
However, it is getting closer.
One thing I feel good about is that I've never used OPUS/CORS numbers over the years for elevations except in areas far from bench marks and where only rough elevations are required.
Chaos would have been created otherwise.
Using established bench marks and applying the geoid to the elevations instead of the ellipsoid was far-sighted to be sure. Stability is the keyB-)
GEOID12A is used to go from a NAD83 (2011) ellipsoid height to NAVD88. The result is not perfect, but the map refered to above will give you an idea of how close it is to "true NAVD88" (whatever that is).