Vdatum

In South Louisiana, it's garbage because of subsidence. Perhaps useful in areas of relative crustal stability.

I can't get it to work, it won't load the data for NY Bay.

Ralph

VDatum is an interpolation program that uses a grid constructed from differences between two different vertical datums, primarily NGVD29 and NAVD88 as of about 1990. There have been no updates. However, the algorithm was developed by Commander Warren Dewhurst, NOAA, back in the early 1980s for his Ph.D. dissertation at Ohio State University. It was later adapted for vertical control at NGS.

The software can be implemented with boxed limits of area. Sounds like your area of interest was inadvertently boxed out.

I suggest that you call the dudes at NGS and ask for help with your area of interest.

Start with Dave Doyle, and he'll direct you to the proper person.

> VDatum is an interpolation program that uses a grid constructed from differences between two different vertical datums, primarily NGVD29 and NAVD88 as of about 1990. There have been no updates. However, the algorithm was developed by Commander Warren Dewhurst, NOAA, back in the early 1980s for his Ph.D. dissertation at Ohio State University. It was later adapted for vertical control at NGS.
>
> The software can be implemented with boxed limits of area. Sounds like your area of interest was inadvertently boxed out.
>
> I suggest that you call the dudes at NGS and ask for help with your area of interest.
>
> Start with Dave Doyle, and he'll direct you to the proper person.

Hi Prof,
Yes, I spoke to Dave D. yesterday and he directed me to the NOAA guys. I sent them an email with screenshots of my Vdatum folder and all the error messages. I loaded the libraries for greater NY bay and NY/NJ Harbor. I don't think I did it right and they removed the link to the
"step by step" installation guide from their website. So I will patiently await a reply from NOAA.

Cheers,
Ralph

Dear Ralph,

I'm the guy that built VERTCON 2.0 and the original versions (up to 1.06)
of VDatum back when I was working at NGS. To be specific, VDatum
transforms between 30+ vertical datums (including tidal datums such as
Mean Lower Low Water). One of the grids inside VDatum is a piece of the
VERTCON 2.0 NGVD29/NAVD88 grid. Another grid is a piece of GEOID99 (as
of VDatum version 1.06).

Anyway, if you just need to go between NGVD29 and NAVD88, you can use
VERTCON 2.0. On the the other hand, it you just need to transform between
ellipsoidal height and NAVD88, then you can use the most recent NGS geoid
model. These are online at the NGS Geodetic Tool Kit (and PC versions,
too).

If you really need tidal datum transformation, and you can't get going
with NGS/NOS, I can provide the old 1.06 version for the New York Bight.
It covers roughly 39-41N 72-75W. Fair warning -- this route will require
you to have Java installed on your computer. And it will have an old
geoid model in version 1.06. Also, it will have the old, original version
of the New York Bight model. (It is 10 years old -- you may want to wait)

If you can wait, NGS/NOS will certainly try to get the best
version (2.3.x) working for you. They are actively maintaining VDatum:

http://vdatum.noaa.gov/about/currentevents.html#about_currentevents_data

Also, standard disclaimer: for survey accuracy, one should drop back
to the original data and databases, and do a fresh least-squares
adjustment to get into the target datum. "Absolute" coordinate
transformations are generally not as accurate.

Just as some background, aside from geoid, VERTCON, and associated
3-D reference frame transformations, VDatum included tidal grids
derived from hydrodynamic models built and/or vetted by the NOS Coast
Survey (which does nautical charts). Warren Dewhurst built the original
NADCON. Warren later got his Ph.D. at Colorado School of Mines by
combining scalar and vector magnetometer data in the mapping of offshore
formations.

Best wishes,

Dennis

:good: Welcome Dennis

> Dear Ralph,
>
> I'm the guy that built VERTCON 2.0 and the original versions (up to 1.06)
> of VDatum back when I was working at NGS. To be specific, VDatum
> transforms between 30+ vertical datums (including tidal datums such as
> Mean Lower Low Water). One of the grids inside VDatum is a piece of the
> VERTCON 2.0 NGVD29/NAVD88 grid. Another grid is a piece of GEOID99 (as
> of VDatum version 1.06).
>
> Anyway, if you just need to go between NGVD29 and NAVD88, you can use
> VERTCON 2.0. On the the other hand, it you just need to transform between
> ellipsoidal height and NAVD88, then you can use the most recent NGS geoid
> model. These are online at the NGS Geodetic Tool Kit (and PC versions,
> too).
>
> If you really need tidal datum transformation, and you can't get going
> with NGS/NOS, I can provide the old 1.06 version for the New York Bight.
> It covers roughly 39-41N 72-75W. Fair warning -- this route will require
> you to have Java installed on your computer. And it will have an old
> geoid model in version 1.06. Also, it will have the old, original version
> of the New York Bight model. (It is 10 years old -- you may want to wait)
>
> If you can wait, NGS/NOS will certainly try to get the best
> version (2.3.x) working for you. They are actively maintaining VDatum:
>
>> http://vdatum.noaa.gov/about/currentevents.html#about_currentevents_data
>
> Also, standard disclaimer: for survey accuracy, one should drop back
> to the original data and databases, and do a fresh least-squares
> adjustment to get into the target datum. "Absolute" coordinate
> transformations are generally not as accurate.
>
> Just as some background, aside from geoid, VERTCON, and associated
> 3-D reference frame transformations, VDatum included tidal grids
> derived from hydrodynamic models built and/or vetted by the NOS Coast
> Survey (which does nautical charts). Warren Dewhurst built the original
> NADCON. Warren later got his Ph.D. at Colorado School of Mines by
> combining scalar and vector magnetometer data in the mapping of offshore
> formations.
>
> Best wishes,
>
> Dennis

Thank You Dennis,
Mr. Bang Le at NOAA (through Dave Doyle) was able to assist me. It appears there are some navigational issues on the NOAA site, including broken links to the step by step installation guide. I had the regional files but I was missing some other stuff.
Here's the link that Mr. Le, provided me:

http://vdatum.noaa.gov/subdownload/download_regional.php

Once I followed these steps it worked like a charm.

Thanks again Dennis for reaching out and welcome to the Board!

I also want to thank Messrs Doyle and Le, keep up the good work guys

Ralph

I want to avoid NGVD 29 at all costs, so vertcon wasn't the answer. Brooklyn Borough Datum is tied in to NGVD 29, if I get into all that, I have 4 out of a possible 40 different datums within the Borough of Brooklyn that correlate to this project, including Brooklyn Borough, Brooklyn Sewer, Brooklyn Highway and Marine and Aviation. And each has an offset to a water level, mean, high, low, MHHW etc. In addition you'll get guys dropping the words "Mean Sea Level at Sandy Hook". So in order to avoid confusion we'll deal mainly in NAVD 88 and MHW if necessary.

Cheers,
Ralph