Working with vertical coordinate systems

[YigalMuntner]

I'm looking for a way to perform a height (z value) transformation from one vertical datum to another one. Both vertical datums exist in ArcGIS list. If I define a horizontal coordinate system, then I have a tool to project the data to another horizontal coordinate system, and set the correct datum transformation.

I don't see a place to do the same between 2 vertical coordinate systems. Does this funcionality exist in ArcGIS Desktop  10.3.1?

Alternatively, can I do it using ArcObjects?

Thanks,

Yigal

[MelitaKennedy]

Is it a feature class or shapefile? If it's a feature class, you made need to create a new feature class with the xy + z coordinate systems you want, and then load the data into it.

[JoelCusick]

Hi Melita,

Could we start a new Thread on 10.5 forward with Vertical?  There isn't clear directions (maybe i'm just dumb) on 10.5 Desktop / 10.6 Desktop and ArcGIS Pro on what the Coordinate system package does.  Its just a minor thing, but I'm reading the extra install package is only vertical related, providing transformation capacity.  So, even the name "ArcGIS Coordinate Systems Data is not precise.  Should this be renamed "ArcGIS Vertical Coordinate Systems Package" or something like that.

In any case, were getting a bit lost, or can you direct to a place in support that specifically speaks to what the package does, how to install, etc.

thanks.

joel

[MelitaKennedy]

Hi Joel, 

Yes, I'm supposed to write a knowledge base/technical article about it...and got distracted about halfway through. 

Short info is that all new transformation files--both horizontal and vertical--are being put into the ArcGIS Coordinate Systems Data setup. GEOCON v1.0 is there and at ArcGIS Desktop 10.6 / ArcGIS Pro 2.1, we also added NTv2 files for Canada, Switzerland, Spain, and the United Kingdom. On the vertical side, we added geoid files for Japan and New Zealand. 

Also at these versions, we merged the ArcGIS Pro all users/per machine and the ArcGIS Desktop/Server CSD setups so you only need to install it once. If you're using ArcGIS Pro per-single-user, there's a separate CSD per-single-user setup. Single-user setup is usually done if the person installing the software is not installing as an administrator. In that case, the software gets installed to the user's account location (C:\Users\<user name>). 

You don't have to install everything in the CSD setup. There are sections for 

North America (GEOCON)

NTv2

Vertical World 1x1 (the 990 MB EGM2008 file)

Vertical (all other vertical files)

so you have partial control over what to install.

Melita

[LuboslavMichalik]

Is it possible to create custom vertical transformation in ArcGIS 10.4 ???

I need to transform Z values from WGS84 to Baltic height, I have custom grid to maintain heigths, but the question is how to implement this.

(2D custom transformation works well, it was easy to create and define parameters.)

[DanPatterson_Retired]

Melita's response above, covers the state in 10.4 https://community.esri.com/thread/171124#comment-582301 just read her entry above

[LuboslavMichalik]

Yes, it works for US, but what about the rest of the world?

[DanPatterson_Retired]

they probably havent gotten around to it yet.  Perhaps it is a demand issue. Perhaps Melita Kennedy​ might have further commentary.

[MelitaKennedy]

Dan has it correct, we put in transformations (and any needed data files) for the US because it's what we had. Much of our information comes from the EPSG Geodetic Parameter Registry​. You can make a request to include information there, and we will implement it, if possible. Or start a support ticket with technical support or a distributor. Information needed would include:

Transformation:

Suggested name

Source/Target VCS

If geoid model/other file needed: what's the base GCS?

Method / file type or description

Parameters / grid file name

Extent/area of use

Accuracy

Source of any data files--can they be downloaded or otherwise obtained and can they be redistributed?

Disclosure: I'm on the geodesy subcommittee that maintains the Esri Geodetic Parameter Registry.

Melita

[PaulLohr]

I am using Desktop 10.6, trying to reproject

from:

WGS 1984 Web Mercator / NAD 1983 (2011) ellipsoid

into:

NAD 1983 (2011) Florida State Plane West (feet) / NAVD 1988 U.S. feet.

After selecting the output coordinate systems and checking the 'vertical' option, a transformation does not show up in the Geographic Transformation section of the dialog.

I did install the separate coordinate systems package.

In order to determine if the transformation exists, I looked for the hvtdefaults.json file in with the separately installed coordinate system data - it wouldn't appear to be there.

As a workaround, I tried reprojecting the horizontal coordinates to NAD 1983 (2011) Florida State Plane West (feet) then in a second step, reprojecting the vertical coordinates from NAD 1983 (2011) ellipsoid to NAVD 1988 U.S. feet. I still did not get a Geographic Transformation in the dialog to make the vertical conversion.

There is a very nice lady from ESRI support (India) working on this issue under case number 02081170. She would probably appreciate a little help. I will pass any information to her or perhaps she could be contacted directly.

Thank you for any help.

[MelitaKennedy]

Hi Paul, 

You've managed to put together a workflow that has several issues! The first is that ellipsoidal heights need to use the same datum as the geographic coordinate system. 

You're mixing a geographic coordinate system WGS 1984 with vertical NAD 1983 (2011) ellipsoidal heights. 

The second issue is converting to NAVD88 (US survey feet). There's no direct transformation between NAD 1983 (2011) ellipsoidal heights and NAVD88 (US survey feet). There are transformations between NGVD29 and NAVD88 (US feet) so the path might be to convert WGS 1984 ellipsoidal heights to NAD 1983 (2011) + ellipsoidal heights. Then NAD 1983 (2011) + ellipsoidal heights to NAD 1983 (2011) + NAVD88 (meters) using the GEOID12B model. To get the US feet however, you would then have to convert to NGVD29, then back to NAVD88 (US survey feet). Unfortunately, that path is 1 geographic/datum transformation plus 3 vertical transformations. Right now, we're limited a path to 4 steps, of which up to 2 can be geographic tfm and 2 can be vertical tfm. You may need to do this in two conversions. 

I think you will also need to do the second portion (NAVD88 to NGVD29 to NAVD88 (US ft) ) in ArcGIS Pro, but not in ArcGIS Desktop. The latter is using the hvtdefaults.json file which is installed in the pedata folder in the core software install. I actually tried to add a few entries last week to it, but could never get them to work properly. ArcGIS Pro is using a function to find paths and is much more flexible. The json file hasn't been updated with newer transformations.

Melita