satmo.geo module

satmo.geo.geo_dict_from_nc(nc_file, proj4string=None)[source]

Retrieves the georeferencing parameters from a netcdf file produced with l3mapgen

See https://oceancolor.gsfc.nasa.gov/forum/oceancolor/topic_show.pl?tid=6429 for justification of the approach used in this function to retrieve the projected extent.

Parameters:
  • nc_file (str) – Path to netcdf file
  • proj4string (str) – Optional. proj4string previously passed to l3mapgen (projection=) retrieved from the file metadata if not provided
Returns:

Dictionary with georeferencing parameters

Examples

# Given a netcdf file produced with: # $l3mapgen ifile=T2016292.L3b_DAY_OC ofile=T2016292.L3B_DAY_RRS_laea.nc resolution=1km south=26 north=40 west=-155 east=-140 projection=”+proj=laea +lat_0=33 +lon_0=-147”

>>> import rasterio
>>> from pprint import pprint
>>>
>>> geo_dict = geo_dict_from_nc('T2016292.L3B_DAY_RRS_laea.nc', "+proj=laea +lat_0=33 +lon_0=-147")
>>> pprint(geo_dict)
{'affine': Affine(1160.0, 0.0, -800596.8665952191,
       0.0, -1160.0, -746017.3077247943),
 'crs': CRS({'lon_0': -147, 'proj': 'laea', 'lat_0': 33}),
 'height': 1361,
 'width': 1295}
>>> geo_dict.update(driver = u'GTiff', dtype = rasterio.float32, count = 1, nodata = -32767)
>>>
>>> import numpy as np
>>>
>>> nc_con = nc.Dataset(file_path)
>>> rrs_555 = nc_con.variables['Rrs_555'][:]
>>> nc_con.close()
>>>
>>> with rasterio.open('rrs_555.tif', 'w', **geo_dict) as dst:
>>>     dst.write_band(1, rrs_555.astype(rasterio.float32))
satmo.geo.get_raster_meta(x, **kwargs)[source]

Retrieve a full meta dict as required by rasterio from a nc or tiff file

driver is always assigned geoTiff, and lzw tiff compression is enabled

Parameters:
  • x (str) – Level L3m filename (tif or netcdf). Must comply with OC standards defined in CONVENTIONS.md
  • **kwargs – ONly one implemented: proj4string (str): OPtional, passed to geo_dict_from_nc()
Returns:

A dictionary as used by rasterio
Return type:

dict