Select geographic transformation used when reprojecting

Question

Is it possible to select the geographic transformation that is used when reprojecting the layers in QGIS?

It seems like ESRI defaults to EPSG 1900 when reprojecting the layer from NAD 83(HARN) to WGS 84 (which is weird considering EPSG 1901 supersedes it)

https://epsg.io/1900

Meanwhile, QGIS seems to default to EPSG 1580 when reprojecting the layer from NAD 83(HARN) to WGS 84 and does not give the option to change it.

https://epsg.io/1580

I believe this might have something to deal with selecting the geographic transformation in QGIS:

+towgs84=0,0,0,0,0,0,0

And I believe that this stack exchange question is related to my issue: Converting NAD 83 to WGS 84 in PostGIS

Answer 1

If accuracy of +/- 1 meter is not good enough then you can configure a new custom projection.

Follow the QGIS documentation from

http://docs.qgis.org/2.18/en/docs/user_manual/working_with_projections/working_with_projections.html#custom-coordinate-reference-system

The proj parameters should probably be as in the answer Converting NAD 83 to WGS 84 in PostGIS

Take the definition that QGIS is using as a template

# NAD83(HARN) / North Carolina (ftUS)
<3404> +proj=lcc +lat_1=36.16666666666666 +lat_2=34.33333333333334 +lat_0=33.75 +lon_0=-79 +x_0=609601.2192024384 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=us-ft +no_defs  <>

Insert the better know +towgs84 parameters

proj=lcc +lat_1=36.16666666666666 +lat_2=34.33333333333334 +lat_0=33.75 +lon_0=-79 +x_0=609601.2192024384 +y_0=0 +ellps=GRS80 +towgs84=-0.99343,-1.90331,-0.52655,0.02591467,0.00942645,0.01159935,0.00171504 +units=us-ft +no_defs  <>

I can see different parameter values in http://www.georepository.com/transformation_1901/NAD83-HARN-to-WGS-84-3.html but unfortunately I can't say if they are better or not than those given by @mkennedy.