QGIS Version 2.18.7 and ArcGIS 10.2
Working on a Project in Northern Nicaragua and have come across some issues in projections and transformations that are a bit above my head.
Nicaragua government uses EPSG:26716 (NAD27 Zone 16N)
- Field Data Collected using Garmin Handheld GPS64
- Datum set to NAD27 Central, Ellipsoid: Clarke 1866
QGIS Project set to EPSG:26716, OTF transformation enabled
Within QGIS project I import a Google or Bing satellite image using Quickmapservices. Confirm the project is still in EPSG:26716. I then import a .csv of points from a legal landsurveyor performed in EPSG:32616. I specify the x/y and the coordinate system. The points plot exactly as they should in relation to the image. Now if I import a .csv of the same points collected in NAD27CENTRAL from a hand-held Garmin (supposedly EPSG:26716) and specify the coordinate system as EPSG:26716 they plot a consistent 112m south of where they should be on the image.
The difference in y coordinate value between WGS84 and NAD27 is -196m
I've included an image illustrating this shift using a nearby point in a courtyard. The red star is in the correct position relative to the image. it was collected in WGS84.
The blue star was collected in NAD27Central (EPSG26716)
If I save the blue star as a new shapefile specifying the coordinate system as EPSG:26716 the resulting nad27 coordinates in EPSG:26716 are 542063mE 1456236mN.
EPSG32616 coordinate in field 542063mE 1456327mN EPSG26716 coordinate in field 542053mE 1456131mN EPSG26716 coordinate from EPSG32616 in QGIS 542063mE 1456236mN
Using ArcGIS 10.2 I can start a new project in EPSG:26716, import the survey points in 32616, specify the coordinate system then transform them using NAD_1972_To_WGS_1984_2 and the points will line up with those collected using the Garminm NAD27 projection, however, this does not line up with basemap imagery form ArcGIS Online.
How do I tackle this discrepancy?