1. Marc Véronneau Canadian Geodetic Survey, Surveyor General Branch
Canada’s Geodetic Reference Frames: Geometric and Vertical Geospatial Summit
Marc Véronneau
Canadian Geodetic Survey, Surveyor General Branch

2. Outline Geometric Reference Frame (Canada) … 3
Vertical Reference Frame (Canada) … 6
Questions? … 15
I will first outline what the height modernisation project is about. Then we will move into an explanation of the current height system CGVD28 and introduce CGVD2013, the new height system. We will then emphasize that ours is a dynamic planet with changing heights. The final three slides will discuss height labelling, briefly go over the tools available and a short summary of the main points to take away from this presentation.

3. Geometric Reference Frame (Canada)
Canadian Geodetic Survey publishes coordinates in NAD83(CSRS) v6 epoch
Each province adopted a specific version/epoch (e.g., Quebec and New Brunswick use NAD83(CSRS) v2 epoch ).
Provinces can upgrade to a newer version when they are ready.
Canadian Geodetic Survey has no plans to replace NAD83(CSRS).
Canadian Geodetic Survey is collaborating with the National Geodetic Survey in the realization of the new (North) American geometric reference frame.
Canadian Geodetic Survey will publish coordinates in the new geometric reference frame
Station reports, NRCan’s CSRS-PPP, TRX software.

4. Geometric Reference Frames
ITRF88
ITRF89
ITRF90
ITRF91
ITRF92
ITRF93
ITRF94
ITRF96
ITRF97
ITRF2000
ITRF2005
ITRF2008
ITRF2014*
International Frames
North American Frames
Grid
transformation
NAD27
Latitude and Longitude
Parameter
transformation
NAD83(Original)
Latitude and Longitude
Canada
NAD83(CSRS) v6 e
NAD83(NSRS/CSRS)
Latitude, Longitude
and Ellipsoidal Height
Equivalent
USA
NAD 83(2011) e
ITRF20xx/NAD 2022
* scheduled for 2015

5. Station Report (Example)
Select coordinates type (geographic)
Select a hybrid or gravimetric geoid model (CGG2013)
Select reference frame (NAD83(CSRS))
New reference frame would be added to the drop-box list
Select epoch (2010.0)
Velocities of the station with respect to the reference frame
Height from GNSS and selected geoid model
Height of the station from adjustment of the levelling network

6. Vertical Reference Frame (Canada)
Canada adopted CGVD2013 in November 2013.
Defined by a specific equipotential surface (W0 = 62,636,856 m2/s2)
Realized by a geoid model (CGG2013)
Compatible with GNSS technology
Canada adopted a geoid-based vertical datum because …
Cost in maintaining and expanding a levelling network for a country as vast as Canada
No access to CGVD28 in remote regions
New technologies available (e.g., GNSS, satellite gravimetry)
Distortions in CGVD28 (~1.2 m at the national scale)
Canada has the support from the provinces in the implementation of the new vertical reference system.
Overall, Canadian users acknowledge that the benefits of a geoid-based datum outweigh disadvantages [HAL report, 2006].
Main concerns relate to cost in converting legacy data, and confusion in heights

7. Vertical Reference Frame (Canada)
CGVD28 continues to co-exist with CGVD2013 during the transition period
Readjustment of the levelling network with constraints to coincide with CGVD2013; Publish bench marks in CGVD2013 and CGVD28; GNSS-derived orthometric heights prevail over the heights from the levelling adjustment.
CGS stopped maintenance of the bench marks of the national first-order levelling network since 2002; Bench marks are not maintained by GNSS observation either.
CGS cannot confirm stability of the bench marks.
Canada’s geodetic infrastructure
~90 continuously tracking reference stations (federal/provincial)
~200 force-centered pillars (passive stations)
Provincial High Precision Networks, Commercial RTK
Use of CGVD2013 (still early stage)
Federal agencies (e.g., NRCan (floodplain mapping), Transport (airport), Environment Canada (inland water; transboundary waters))
Provincial agencies initiated migration to CGVD2013

8. North American Vertical Datums (Now)
Transboundary Waters
CGVD28 (Levelling; GNSS/HTv2.0) =>
CGVD2013 (Geoid model)
IGLD 85
(Levelling)
NAVD 88 (Levelling; GNSS/Geoid12A)
Courtesy of the International Joint Commission

9. North American Vertical Datum (Objective)
A unified height system for North America based on the equipotential surface:
W0 = 62,636,856 m2/s2
This surface is materialized by a geoid model which integrates satellite, airborne, and surface gravity data.
CGS and NGS agreed on this definition.
This definition is already adopted in Canada (CGVD2013).
Mexico and countries in Central America and Caribbean agreed on this definition.
Coordinating Committee for the Great Lakes and St-Lawrence River System proposed to define IGLD2020 on this surface.
IERS and IAU had already adopted this reference surface in their conventions.
W0 = 62,636,856 m2/s2
Geoid Model

10. Canada’s Levelling network
Constraints
: Continental (32)
: Newfoundland (4)
: Prince Edward Island (1)
: Iles de la Madeleine (1)
: Ile d’Anticosti (1)
: Vancouver Island (2)
: Gauges (12)

11. Active Stations Processed at CGS

12. The difference between NAVD 88 and CGVD2013
HCGVD2013 – HNAVD 88
C.I.: 10 cm
Conversion between NAVD 88 and CGVD2013
Conduct a GNSS survey on bench marks having NAVD 88 elevation
Published elevations at common bench marks
GEOID12A - CGG2013 (above image)

13. Some NRCan’s tools
CSRS-Precise Point Positioning (PPP): Process GPS RINEX files to provide stand-alone coordinates (latitude, longitude, ellipsoidal height and orthometric height). Works any where in the world. [on-line]
GPS-H: Convert ellipsoidal heights to orthometric heights (makes use of any geoid models, works with different types of coordinate systems (geographic, UTM, MTM and Cartesian), and different geometric reference frames (NAD83(CSRS) and ITRF)). Could also convert between vertical datums. [on-line and desktop]
TRX: Transform coordinates between different geometric reference frames (e.g., NAD83(CSRS), ITRF), epochs and coordinate systems (e.g., geographic, UTM, MTM, Cartesian). [on-line and desktop]

14. Labelling Heights
Type of height: Orthometric (H), dynamic (Hd), normal (Hn), ellipsoidal (h), geoid (N)
Height Reference System: NAD83, ITRF, CGVD28, CGVD2013, NAVD 88
Height Reference Frame: CSRS v., Geoid model
Precision (e.g., ± 0.05 m)
Epoch (e.g., ) H N
Height: m
Precision: ± 0.01 m
Epoch:
Type of height: Orthometric
Height system: CGVD2013
Height frame: CGG2013
H = ± m CGVD2013(CGG2013) Epoch
Geoid Height: m
Precision: ± m
Epoch: Static
Model: CGG2013
Frame: NAD83(CSRS)
N = ± m CGG2013, NAD83(CSRS) h
Due to this reason (amongst others), height labelling becomes an important aspect of coordinates information. A tag for a height can include five attributes: the type of height, height reference system, the reference frame, the precision and the epoch. The format of the label will vary according to the technique used to determine height. The example here shows a complete tag for a modernized height determined by GNSS where the attributes are the reference system (CGVD2013), reference frame (CGG2013), precision and epoch.
Height: m
Precision: ± m
Epoch:
Type of height: Ellipsoidal (geodetic)
Height system: NAD83
Height frame: CSRS (version if available)
h = ± m NAD83(CSRS) Epoch

15. QUESTIONS? NRCan Contacts: General information:
Philippe Lamothe
Marc Véronneau
Mike Craymer
General information:
Web:
Phone:  
For more information on height modernisation, you can contact Philippe Lamothe at Information Management and Client Services or directly Marc Véronneau or Dr. Jianliang Huang. General information on height modernisation can also be found on our website. Thank you.