6

"Natural Resources Canada (NRCan) has released the Canadian Geodetic Vertical Datum of 2013 (CGVD2013), which is now the new reference standard for heights across Canada. This new height reference system is replacing the Canadian Geodetic Vertical Datum of 1928 (CGVD28)" -- http://www.nrcan.gc.ca/earth-sciences/geomatics/geodetic-reference-systems/9054

Should we GIS people who mainly work in feet or meters care, or is this something only really of interest to high precision (sub-centimeter) professions like land surveyors and geodesists*? If we do care, how do we use make use of it? I haven't found any .PRJ/.WKT/... reference files such as EPSG:5713, the CGVD for 1928.

* don't know the term for someone who studies and practices geodesy

  • When you're asking "how do we make use of it?" are you looking for some examples of where this is used in GIS analysis like viewsheds from LiDAR or converting ellipsoid <-> geoid heights? – SaultDon Jan 28 '15 at 19:20
  • @SaultDon, more about how to have it show up in the list of available vertical coordinate systems when creating a new feature class/dataset. Examples of how and when to use it would be helpful in rounding out the topic though. – matt wilkie Jan 28 '15 at 21:14
5

EPSG has added it as 6647.

At Esri, I have it in a development build, but it's not in ArcGIS 10.3 (hopefully 10.3.1). Here's the Esri WKT for it:

VERTCS["CGVD2013_height",VDATUM["Canadian_Geodetic_Vertical_Datum_of_2013"],PARAMETER["Vertical_Shift",0.0],PARAMETER["Direction",1.0],UNIT["Meter",1.0],AUTHORITY["EPSG",6647]]

This document on height modernization (1.36 MB) from Service New Brunswick shows differences from CGVD28 of +0.55 m in Banff to -0.64 m in Halifax. I would call those differences significant for more than high-end surveying work.

If you (as a GIS person) receive CGVD13 data, you'll want to make sure the metadata reflects that. Also, as it's now the official vertical coordinate reference system, government agencies may start requiring that vertical data use CGVD2013.

EDIT: How to incorporate the new definition

Esri removed the "Coordinate Systems" folder and its thousands of prj files at version 10.0. People used to drop in custom definitions there or move things around. If you're using a 10.0 or later version:

Keep custom prj files in a directory to which you have a folder connection. Then when choosing a coordinate system, you can use the "import" option to browse to that folder and pick a prj file.

(Tip: use "add to Favorites" context menu, which is a shortcut for copying prj files in the ArcGIS "Favorites" location, C:\Users\your_login\AppData\Roaming\ESRI\Desktop10.X\ArcMap\Coordinate Systems in Windows 7; replace Desktop10.x with your major release version (10.0 / 10.1 / etc.).)

The coordinate systems "picker" is smart enough that a vertical coordinate system prj file will not show up in ArcMap data frame properties' Coordinate System tab, but is available if you're using Define Projection Tool, or a data's property page in ArcCatalog.

(* You did get the name of someone who studies and practices geodesy correct!)

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