Source code for poets.image.geotiff

# Copyright (c) 2014, Vienna University of Technology (TU Wien), Department
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# Author: Isabella Pfeil, isy.pfeil@gmx.at
# Creation date: 2014-09-11

"""
GeoTIFF operations.
"""

import numpy as np


[docs]def lonlat2px_gt(img, lon, lat, lon_min, lat_min, lon_max, lat_max): """ Converts a pair of lon and lat to its corresponding pixel value in an geotiff image file. Parameters ---------- img : Image File, e.g. PNG, TIFF Input image file lon : float Longitude lat : float Latitude lon_min, lat_min : float lower left coordinate of geotiff lon_max, lat_max : float upper right coordinate of geotiff Returns ------- Row : float corresponding pixel value Col : float corresponding pixel value """ w, h = img.size londiff = lon_max - lon_min latdiff = lat_max - lat_min mw = w / londiff mh = h / latdiff row = (-lat + lat_max) * mh col = (lon - lon_min) * mw return row, col
[docs]def px2lonlat_gt(img, lon_px, lat_px, lon_min, lat_min, lon_max, lat_max): """ Converts two arrays of row and column pixels into their corresponding longitude and latitude arrays Parameters ---------- img : Image file Image which the pixel values refer to lon_px : np.array array of column pixels lat_px : np.array array of row pixels Returns ------- lon_new : np.array List of corresponding longitude values lat_new: np.array List of corresponding latitude values lon_min, lat_min : float lower left coordinate of geotiff lon_max, lat_max : float upper right coordinate of geotiff """ w, h = img.size londiff = lon_max - lon_min latdiff = lat_max - lat_min mw = w / londiff mh = h / latdiff lon_new = np.zeros(len(lon_px)) lat_new = np.zeros(len(lat_px)) for i in range(0, len(lon_px)): lon_new[i] = lon_min + lon_px[i] / mw for i in range(0, len(lat_px)): lat_new[i] = lat_max - lat_px[i] / mh return lon_new, lat_new