Add Ground Control Points

Geoxarray allows writing Ground Control Points (GCPs) to an Xarray DataArray or Dataset. If possible it is recommended to write 1D coordinate arrays (see Add spatial coordinates), but this requires data to be uniformly spaced. For more information on coordinates see the Coordinates documentation.

GCPs used with Geoxarray must be formatted as GeoJSON in a normal Python str object.

import xarray as xr
import numpy as np
import geoxarray

gcp_data = """{'type': 'FeatureCollection', 'features': [
    {'type': 'Feature', 'properties': {'id': '1', 'info': '', 'row': 0.0, 'col': 0.0},
     'geometry': {'type': 'Point', 'coordinates': [33.03, 61.80, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '2', 'info': '', 'row': 0.0, 'col': 530.0},
     'geometry': {'type': 'Point', 'coordinates': [32.64, 61.85, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '3', 'info': '', 'row': 0.0, 'col': 1060.0},
     'geometry': {'type': 'Point', 'coordinates': [32.25, 61.90, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '4', 'info': '', 'row': 0.0, 'col': 1590.0},
     'geometry': {'type': 'Point', 'coordinates': [31.86, 61.95, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '5', 'info': '', 'row': 0.0, 'col': 2120.0},
     'geometry': {'type': 'Point', 'coordinates': [31.47, 62.00, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '6', 'info': '', 'row': 0.0, 'col': 2650.0},
     'geometry': {'type': 'Point', 'coordinates': [31.08, 62.04, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '7', 'info': '', 'row': 0.0, 'col': 3180.0},
     'geometry': {'type': 'Point', 'coordinates': [30.68, 62.09, 126.43]}}]}"""
my_data_arr = xr.DataArray(
    np.zeros((20, 10)),
    dims=("y", "x"),
     coords={},
)
new_data_arr = my_data_arr.geo.write_gcps(gcp_data)
print(new_data_arr.geo.gcps)

Which will give you the GCP GeoJSON back:

{'type': 'FeatureCollection', 'features': [
    {'type': 'Feature', 'properties': {'id': '1', 'info': '', 'row': 0.0, 'col': 0.0},
     'geometry': {'type': 'Point', 'coordinates': [33.03, 61.80, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '2', 'info': '', 'row': 0.0, 'col': 530.0},
     'geometry': {'type': 'Point', 'coordinates': [32.64, 61.85, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '3', 'info': '', 'row': 0.0, 'col': 1060.0},
     'geometry': {'type': 'Point', 'coordinates': [32.25, 61.90, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '4', 'info': '', 'row': 0.0, 'col': 1590.0},
     'geometry': {'type': 'Point', 'coordinates': [31.86, 61.95, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '5', 'info': '', 'row': 0.0, 'col': 2120.0},
     'geometry': {'type': 'Point', 'coordinates': [31.47, 62.00, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '6', 'info': '', 'row': 0.0, 'col': 2650.0},
     'geometry': {'type': 'Point', 'coordinates': [31.08, 62.04, 126.43]}},
    {'type': 'Feature', 'properties': {'id': '7', 'info': '', 'row': 0.0, 'col': 3180.0},
     'geometry': {'type': 'Point', 'coordinates': [30.68, 62.09, 126.43]}}]}