HT2 Vertical Datum Issue

[Resourceful]

Good evening,

I am trying to load the CGVD28 - HT2 vertical datum.  I followed the download procedure and inserted the file into the geoids folder as per the instructions on the web page.

I also loaded CGVD 2013, it automatically populated for me on the convert tab.

But, I am trying to access HT2 because it is becoming the popular request of some of my clients...  I even tried the procedure described at this link, to no avail.

https://agisoft.freshdesk.com/support/solutions/articles/31000148332-how-to-use-height-above-geoid-for-the-coordinate-system

The description here is not consistent with what I am seeing in the program.

Let me know how to proceed, thanks.

[Alexey Pasumansky]

Hello Resourceful,

Can you please specify, which planar (geographic/projected) system you are planning to use together with CGVD28 geoid?

[Resourceful]

Good evening Alexey,

I am attempting to use it with NAD83(CSRS).  This projection pulls up the CGVD2013, but not the CGVD28.  It used to work on the previous version of Metashape, now I am not seeing the ability to add HT2 to any projections.

Let me know what you think, most likely I am missing something.

Please re-issue your instructions for the latest version of MetaShape, or an online course would be amazing!

Thank you,

[Paulo]

Hello Resourceful,

I think you can do following:

1. in Select Coordinate System window, select NAD83(CSRS) and click edit button (see attached captura0.jpg);
2. in Edit Coordinate System window, find CGVD28 height (ESPG::5713) for Vertical CS and input new name e.g. Nad83(CSRS) + CGVD28 height and click OK (see attached captura1.jpg);
3. accept message saying selected vertical datum is unavailable and click tools (Settings) button (see attached captura2.jpg);
4. in Datum Transformation Settings window, select Add... for Geoid height and navigate to where your HT2_0.tif resides and select it (may be geoids folder of MS installation folder). In Import Geoid window, click OK  (see attached captura3.jpg).

Voilá, your Compound Reference System using GCS NAD83(CSRS) with CGVD28 height is created!
Same procedure can be used to create CRS for projected coordinate system, e.g. NAD83(CSRS) / UTM14N + CGVD28 height....

[Resourceful]

Thank you Paulo, that seems to have worked.  I am going to compare a few things in GIS, but I think that is what I am looking for.  It is notable though, prior to the last update or so the CGVD data would be auto populated whenever I use the pull down menus for this.  Now, it automatically shows CGVD2013, but that's not quite what I am looking for.

Thank you.