GCCVIEW State of Good Repair

Migration of the coordinate system from NAD27 MTM Zone 10 to NAD83 (CSRS) / MTM zone 10

NAD83 (CSRS)

North American Datum of 1983 (sometimes called NAD83) is the current reference system adopted as a national standard by most federal and provincial agencies in Canada. Neighbouring municipalities of the City of Toronto are mostly using NAD83. The previous datum used (NAD27) made it difficult to share accurate geographic data with external municipalities and consultants.

The North American Datum of 1983 (Canadian Spatial Reference System) is the improved realization of NAD83 for Canada. It is often referred to as NAD83 (CSRS) or just CSRS. It is the most current and practical representation of the City of Toronto.

For further information, see The Canadian Spatial Reference System (CSRS).

NAD83 (CSRS) / MTM zone 10

The City of Toronto uses the North American Datum of 1983 (NAD83) Canadian Spatial Reference System (CSRS) with a Modified Transverse Mercator (MTM) projection with for its geographic layers.

It is available in the CITYMTM data schema in GCCVIEW IGEDMG2.

This coordinate system can be referred to using EPSG code: 2952 and Well-known Text: NAD83 (CSRS) / MTM zone 10. Technical details of this coordinate reference system can be found in the IOGP's EPSG Geodetic Parameter Dataset.

NAD83 (CSRS) / MTM Zone 10 is the recommended coordinate system for data management purposes going forward.

Migrating to NAD83 (CSRS) / MTM zone 10

CITYPRJ (NAD27 MTM Zone 10) and CITYGCS (WGS84) data will remain active in the IGEDM database until the end of 2019. The GCC highly encourages you to transition to the IGEDMG2 database using CITYMTM (NAD83 (CSRS) / MTM Zone 10) data as early as possible. Please contact gcc@toronto.ca if you need assistance.

There will be very limited corporate support for NAD27 MTM Zone 10 going forward. It is recommended to switch to NAD83 (CSRS) as soon as possible.

Reprojection of Data from NAD27 MTM Zone 10 to NAD83 (CSRS) / MTM Zone 10

ArcCatalog

Prerequisites – ArcCatalog:

• Download this geographic transformation file (.gtf) to your ArcGIS Desktop user profile location:
  C:\Users\<username>\AppData\Roaming\ESRI\Desktop10.x\ArcToolbox\CustomTransformations
  – Create the "CustomTransformations" folder if necessary

• Download this transformation file (.gsb) to the ArcGIS Desktop install folder location:
  C:\Program Files (x86)\ArcGIS\Desktop10.x\pedata\ntv2\canada
  – Create the "canada" folder if necessary

For Internet Explorer (IE) users

Please "right click" the file "Save target as..." to initiate the above file downloads.

Steps to Project in ArcCatalog:

1. Open ArcCatalog

2. Launch ArcToolBox

3. Launch the Project Geoprocessing Tool (Data Management Tools> Projections and Transformation > Project

4. In Input Dataset or Feature Class, browse to your input NAD27 MTM 10 dataset

5. The Input Coordinate System updates to show MTM_3Degree

6. Specify an Output Dataset or Feature Class

7. Click on the button beside Output Coordinate System screen to bring up the Spatial Reference Properties window

8. In the Search text box, type CSRS and click Search

9. Expand Project Coordinate Systems > National Grids > Canadaand then select NAD 1983 CSRS MTM 10

10. Click on the star icon to add to your list of favorites for easy access

11. With NAD 1983 CSRS MTM 10 selected, click OK

12. By default, the tool selects the custom transformation installed Toronto NAD 1927 (1974) to NAD 1983 CSRS (1997) Version 1. Click OK to begin reprojecting

ArcGIS Pro

Prerequisites – ArcGIS Pro:

• Download this geographic transformation file (.gtf) to your ArcGIS Pro user profile location:
  C:\Users\<username>\AppData\Roaming\ESRI\ArcGISPro\ArcToolbox\CustomTransformations
  – Create the " CustomTransformations" folder if necessary

•  

• Download this transformation file (.gsb) to the ArcGIS Pro install folder location:
  C:\Program Files\ArcGIS\Pro\Resources\pedata\ntv2\canada.
  – Create the "canada" folder if necessary

For Internet Explorer (IE) users

Please "right click" the file "Save target as..." to initiate the above file downloads.

Steps to Project in ArcGIS Pro:

1. Open ArcGIS Pro

2. In the Analysis ribbon, click on Tools to open the Geoprocessing window

3. In Find Tools, search for Project and launch the Project (Data Management Tools) tool

4. In Input Dataset or Feature Class, browse to your input NAD27 MTM 10 dataset

5. Specify an Output Dataset or Feature Class

6. Click on the button beside Output Coordinate System to bring up the Spatial Reference Properties window

7. In the Search text box, type CSRS and hit Enter on your keyboard

8. Expand Projected Coordinate Systems > National Grids > Canadaselect NAD 1983 CSRS MTM 10

9. Click on the star icon to add to your list of favorites for easy access

10. With NAD 1983 CSRS MTM 10 selected, click OK

11. By default, the tool selects the custom transformation installed Toronto NAD 1927 (1974) to NAD 1983 CSRS (1997) Version 1. Click OK to begin reprojecting

Reprojection on-the-fly NAD83 CSRS to and from WGS84

In ArcGIS Desktop, the geographic coordinate system of a data frame or map can be different from the native geographic coordinate system of the data sources. When displaying multiple datasets with different geographic coordinate systems, you need a geographic transformation. Geographic transformations translate coordinates from one geographic coordinate system to another. ArcGIS Desktop will then project the data 'on-the-fly' to the coordinate system that is set for the data frame or map using the geographic transformation chosen.

When working with geographic transformations, if no mention is made of the direction, ArcGIS Desktop will handle the directionality automatically. For example, if converting data from WGS 1984 to NAD 1983 CSRS, you can pick a transformation called NAD_1983_CSRS_to_WGS_1984_1 and the software will apply it correctly.

Caution: If you need to edit or perform analysis on your data, it is good practice to work with data in the same coordinate system. Use the Project tool to project spatial data from one coordinate system to another. Please refer to the 'Reprojection of Data' Section for detailed instructions.

Steps to Project in ArcCatalog

1. Open ArcMap

2. Add your first layer to the map, for example a CITYMTM layer (NAD 1983 CSRS MTM 10).

3. Right click on the active Data Frame 'Layers' < Properties < Coordinate System tab

4. Currently, the data frame coordinate system is defined as the first layer that was added to ArcMap, in this case, NAD_1983_CSRS_MTM_10.

5. You may add this projection to your favorites list for easier access in the future

6. Add your second layer to the map, for example, a layer from a web service. City's web services are published in WGS84 Web Mercator Auxiliary Sphere. ArcMap recognizes that there is a datum difference and displays A Geographic Coordinate System Warning.

7. Click the Transformations button

8. Choose Convert from 'GCS_WGS_1984' into 'GCS_North_American_1983_CSRS' using 'NAD_1983_CSRS_To_WGS_1984_1' and click OK.

9. Same transformation method can be used when converting from 'GCS_North_American_1983_CSRS' into 'GCS_WGS_1984' depends on which coordinate system the user choose to see their data in.

This process merely transforms the coordinates 'on-the-fly' without having to re-project the data. Failure to do so will result in an apparent shift when displaying both coordinate systems together.

Steps to Project on-the-fly in ArcGIS Pro

1. Open ArcGIS Pro

2. Add a new map to your project, the map will start with the default Basemap (WGS84 Web Mercator Auxiliary Sphere)

3. Add your layer to the map, for example a CITYMTM layer (NAD 1983 CSRS MTM 10).

4. ArcGIS Pro recognizes that there is a datum difference and displays the Transformation Warning window from NAD 1983 CSRS MTM 10 to the datum of the Basemap (GCS WGS 1984)

5. In the GCS WGS 1984 Transformation drop down list, select 'NAD 1983 CSRS To WGS 1984 1' and click OK

6. Your features will now draw on the Basemap with no apparent shift

Same transformation method can be used when converting from 'GCS WGS 1984' into 'GCS North American 1983 CSRS' depends on which coordinate system the user choose to see their data in.

Reprojection on-the-fly NAD83 CSRS to and from NAD27

In ArcGIS Desktop, the geographic coordinate system of a data frame or map can be different from the native geographic coordinate system of the data sources. When displaying multiple datasets with different geographic coordinate systems, you need a geographic transformation. Geographic transformations translate coordinates from one geographic coordinate system to another. ArcGIS Desktop will then project the data 'on-the-fly' to the coordinate system that is set for the data frame or map using the geographic transformation chosen.

When working with geographic transformations, if no mention is made of the direction, ArcGIS Desktop will handle the directionality automatically.

Caution: If you need to edit or perform analysis on your data, it is good practice to work with data in the same coordinate system. Use the Project tool to project spatial data from one coordinate system to another. Please refer to the 'Reprojection of Data' Section for detailed instructions.

Steps to Project on-the-fly in Arc Map

Transformation method: Toronto NAD 1927 (1974) to NAD 1983 CSRS (1997) Version 1

Prerequisites: Install the custom geographic transformation file (.gtf) and transformation file (.gsb) to ArcGIS Desktop. Please refer to the 'Reprojection of Data' < 'ArcCatalog'/'ArcGIS Pro' 'Prerequisites' Section for detailed instructions.

Follow same steps as in the NAD83 CSRS to and from WGS84 section.

Steps to Project in ArcGIS Pro

Follow same steps as in the NAD83 CSRS to and from WGS84 section.

Web Service Changes to Web Mercator

The NAD27 MTM Zone 10 web services (e.g. cot_geospatial_mtm) will be decommissioned at the end of 2019. From that point forward web services will only be available in Web Mercator (EPSG: 3857).

Web Mercator is currently the standard for sharing data on the Web. By decommissioning the NAD27 MTM Zone 10 web services, we will ensure that our map data aligns properly with other services such as popular content providers Microsoft Bing Maps, Google Maps, and ESRI ArcGIS Online, which have standardized their services on the Web Mercator coordinate system.

If you have web applications that are using the NAD27 MTM Zone 10 web services or basemaps, please contact gcc@toronto.ca as early as possible for assistance.