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124 lines
4.4 KiB
Python
124 lines
4.4 KiB
Python
# -*- coding: utf-8 -*-
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"""
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***************************************************************************
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raster.py
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---------------------
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Date : February 2013
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Copyright : (C) 2013 by Victor Olaya and Alexander Bruy
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Email : volayaf at gmail dot com
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***************************************************************************
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* *
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* This program is free software; you can redistribute it and/or modify *
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* it under the terms of the GNU General Public License as published by *
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* the Free Software Foundation; either version 2 of the License, or *
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* (at your option) any later version. *
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* *
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***************************************************************************
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"""
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__author__ = 'Victor Olaya and Alexander Bruy'
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__date__ = 'February 2013'
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__copyright__ = '(C) 2013, Victor Olaya and Alexander Bruy'
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# This will get replaced with a git SHA1 when you do a git archive
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__revision__ = '$Format:%H$'
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import struct
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from osgeo import gdal
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from osgeo.gdalconst import *
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def scanraster(layer, progress):
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filename = unicode(layer.source())
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dataset = gdal.Open(filename, GA_ReadOnly)
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band = dataset.GetRasterBand(1)
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nodata = band.GetNoDataValue()
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for y in xrange(band.YSize):
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progress.setPercentage(y / float(band.YSize) * 100)
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scanline = band.ReadRaster(0, y, band.XSize, 1, band.XSize, 1,
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band.DataType)
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values = struct.unpack('f' * band.XSize, scanline)
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for value in values:
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if value == nodata:
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value = None
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yield value
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def mapToPixel(mX, mY, geoTransform):
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"""Convert map coordinates to pixel coordinates.
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@param mX Input map X coordinate (double)
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@param mY Input map Y coordinate (double)
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@param geoTransform Input geotransform (six doubles)
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@return pX, pY Output coordinates (two doubles)
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"""
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if geoTransform[2] + geoTransform[4] == 0:
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pX = (mX - geoTransform[0]) / geoTransform[1]
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pY = (mY - geoTransform[3]) / geoTransform[5]
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else:
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(pX, pY) = applyGeoTransform(mX, mY, invertGeoTransform(geoTransform))
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return (int(pX), int(pY))
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def pixelToMap(pX, pY, geoTransform):
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"""Convert pixel coordinates to map coordinates.
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@param pX Input pixel X coordinate (double)
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@param pY Input pixel Y coordinate (double)
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@param geoTransform Input geotransform (six doubles)
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@return mX, mY Output coordinates (two doubles)
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"""
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(mX, mY) = applyGeoTransform(pX + 0.5, pY + 0.5, geoTransform)
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return (mX, mY)
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def applyGeoTransform(inX, inY, geoTransform):
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"""Apply a geotransform to coordinates.
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@param inX Input coordinate (double)
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@param inY Input coordinate (double)
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@param geoTransform Input geotransform (six doubles)
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@return outX, outY Output coordinates (two doubles)
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"""
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outX = geoTransform[0] + inX * geoTransform[1] + inY * geoTransform[2]
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outY = geoTransform[3] + inX * geoTransform[4] + inY * geoTransform[5]
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return (outX, outY)
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def invertGeoTransform(geoTransform):
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"""Invert standard 3x2 set of geotransform coefficients.
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@param geoTransform Input GeoTransform (six doubles - unaltered)
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@return outGeoTransform Output GeoTransform (six doubles - updated)
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on success, None if the equation is uninvertable
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"""
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# We assume a 3rd row that is [1 0 0]
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# Compute determinate
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det = geoTransform[1] * geoTransform[5] - geoTransform[2] * geoTransform[4]
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if abs(det) < 0.000000000000001:
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return
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invDet = 1.0 / det
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# Compute adjoint and divide by determinate
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outGeoTransform = [0, 0, 0, 0, 0, 0]
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outGeoTransform[1] = geoTransform[5] * invDet
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outGeoTransform[4] = -geoTransform[4] * invDet
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outGeoTransform[2] = -geoTransform[2] * invDet
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outGeoTransform[5] = geoTransform[1] * invDet
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outGeoTransform[0] = (geoTransform[2] * geoTransform[3] - geoTransform[0]
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* geoTransform[5]) * invDet
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outGeoTransform[3] = (-geoTransform[1] * geoTransform[3] + geoTransform[0]
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* geoTransform[4]) * invDet
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return outGeoTransform
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