We support the most popular local coordinate systems for all of our imagery. Depending on which coordinate system your GIS application is configured with, you can request imagery in the following coordinate systems:
- Australia - GDA94 and GDA2020
- USA - NAD83
- Canada - NAD83CSRS
- New Zealand - NZGD2000
When requesting imagery using WGS84 coordinate systems, namely EPSG:4326 (WGS 84) and EPSG:3857 (Web Mercator, Spherical Mercator, Pseudo-Mercator), our WMS service will automatically return imagery that has been converted to a local coordinate system as shown in the table below.
|SRS||Australia||Canada||New Zealand||United States|
Assumed datum - for Australian customers
Several web applications assume GDA94 where the datum is not specified. You can see from the table above that in Australia, Nearmap WMS 2.0 defaults to GDA2020.
We provide a way to force the returned imagery to GDA94 with a custom request parameter DATUM . The behaviour of this parameter depends on the projection the imagery is requested in (SRS Parameter), as shown in the table below.
|Projection||DATUM=GDA94||DATUM is omitted (default behaviour)|
|EPSG:4326 (aka WGS84)||GDA94||GDA2020|
|EPSG:3857 (aka Web Mercator)||GDA94||GDA2020|
|Any MGA94 projection||GDA94||GDA94|
|Any MGA2020 projection||GDA2020||GDA2020|
Advantages of assumed datum
If your application relies on assumed GDA94, the alignment and accuracy can be improved by a significant margin, as you can see in the images below.
With GDA94 override