[Gdal-dev] importing SRTM30
Andrey Kiselev
dron at ak4719.spb.edu
Sat Sep 20 10:25:54 EDT 2003
On Thu, Sep 18, 2003 at 03:44:23PM -0400, Joe LeMonnier wrote:
> Forgive my ignorance here but could you tell me how to import the
> SRTM30 in such a way that I can make shaded relief . I am working on a
> Mac and use a few programs for ordinary DEM files. These are: Bryce,
> TopotoImage, MacDem and DemReader. Will any of these work here? How do
> I use Gdal?
You can use gdal_translate utility to produce output file in the format,
suitable for your processing software. SRTM30 can be imported by the
GDAL without problems.
Also I have made a Python script to produce a shaded relief images
(algorithm was stealed from the corresponding PCI task). See that script
attached, those whop are using CVS tree can find it under /pymod/samples
directory. Script works not too fast, but it can be easily rewritten in C.
Andrey
--
Andrey V. Kiselev
Home phone: +7 812 5274898 ICQ# 26871517
-------------- next part --------------
#!/usr/bin/env python
###############################################################################
# $Id: rel.py,v 1.1 2003/09/20 11:43:18 dron Exp $
#
# Project: GDAL Python samples
# Purpose: Script to produce a shaded relief image from elevation data
# Author: Andrey Kiselev, dron at remotesensing.org
#
###############################################################################
# Copyright (c) 2003, Andrey Kiselev <dron at remotesensing.org>
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included
# in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
###############################################################################
#
# $Log: rel.py,v $
# Revision 1.1 2003/09/20 11:43:18 dron
# New.
#
#
import gdal
import gdalnumeric
from gdalconst import *
import Numeric
import sys
from math import *
# =============================================================================
def Usage():
print 'Usage: rel.py -lsrcaz azimuth -lsrcel elevation [-elstep step]'
print ' [-dx xsize] [-dy ysize] [-b band] [-ot type] infile outfile'
print 'Produce a shaded relief image from elevation data'
print
print ' -lsrcaz azimuth Azimuth angle of the diffuse light source (0..360 degrees)'
print ' -lsrcel elevation Elevation angle of the diffuse light source (0..180 degrees)'
print ' -elstep step Elevation change corresponding to a change of one grey level'
print ' (default 1)'
print ' -dx xsize X and Y dimensions (in metres) of one pixel on the ground'
print ' -dy ysize (taken from the geotransform matrix by default)'
print ' -b band Select a band number to convert (default 1)'
print ' -ot type Data type of the output dataset'
print ' (Byte/Int16/UInt16/UInt32/Int32/Float32/Float64/'
print ' CInt16/CInt32/CFloat32/CFloat64, default is Byte)'
print ' infile Name of the input file'
print ' outfile Name of the output file'
print
sys.exit(1)
# =============================================================================
# =============================================================================
def ParseType(type):
if type == 'Byte':
return GDT_Byte
elif type == 'Int16':
return GDT_Int16
elif type == 'UInt16':
return GDT_UInt16
elif type == 'Int32':
return GDT_Int32
elif type == 'UInt32':
return GDT_UInt32
elif type == 'Float32':
return GDT_Float32
elif type == 'Float64':
return GDT_Float64
elif type == 'CInt16':
return GDT_CInt16
elif type == 'CInt32':
return GDT_CInt32
elif type == 'CFloat32':
return GDT_CFloat32
elif type == 'CFloat64':
return GDT_CFloat64
else:
return GDT_Byte
# =============================================================================
infile = None
outfile = None
iBand = 1 # The first band will be converted by default
format = 'GTiff'
type = GDT_Byte
lsrcaz = None
lsrcel = None
elstep = 1.0
xsize = None
ysize = None
# Parse command line arguments.
i = 1
while i < len(sys.argv):
arg = sys.argv[i]
if arg == '-b':
i += 1
iBand = int(sys.argv[i])
elif arg == '-ot':
i += 1
type = ParseType(sys.argv[i])
elif arg == '-lsrcaz':
i += 1
lsrcaz = float(sys.argv[i])
elif arg == '-lsrcel':
i += 1
lsrcel = float(sys.argv[i])
elif arg == '-elstep':
i += 1
elstep = float(sys.argv[i])
elif arg == '-dx':
i += 1
xsize = float(sys.argv[i])
elif arg == '-dy':
i += 1
ysize = float(sys.argv[i])
elif infile is None:
infile = arg
elif outfile is None:
outfile = arg
else:
Usage()
i += 1
if infile is None:
Usage()
if outfile is None:
Usage()
if lsrcaz is None:
Usage()
if lsrcel is None:
Usage()
# translate angles from degrees to radians
lsrcaz = lsrcaz / 180.0 * pi
lsrcel = lsrcel / 180.0 * pi
lx = -sin(lsrcaz) * cos(lsrcel)
ly = cos(lsrcaz) * cos(lsrcel)
lz = sin(lsrcel)
indataset = gdal.Open(infile, GA_ReadOnly)
if indataset == None:
print 'Cannot open', infile
sys.exit(2)
out_driver = gdal.GetDriverByName(format)
outdataset = out_driver.Create(outfile, indataset.RasterXSize, indataset.RasterYSize, indataset.RasterCount, type)
outband = outdataset.GetRasterBand(1)
geotransform = indataset.GetGeoTransform()
projection = indataset.GetProjection()
if xsize is None:
xsize = abs(geotransform[1])
if ysize is None:
ysize = abs(geotransform[5])
inband = indataset.GetRasterBand(iBand)
if inband == None:
print 'Cannot load band', iBand, 'from the', infile
sys.exit(2)
outline = Numeric.zeros((1, inband.XSize), gdalnumeric.GDALTypeCodeToNumericTypeCode(type))
lineprev = inband.ReadAsArray(0, 0, inband.XSize, 1, inband.XSize, 1)
outband.WriteArray(outline, 0, 0)
gdal.TermProgress(0.0)
linecur = inband.ReadAsArray(0, 1, inband.XSize, 1, inband.XSize, 1)
outband.WriteArray(outline, 0, inband.YSize - 1)
gdal.TermProgress(1.0 / inband.YSize)
for i in range(1, inband.YSize - 1):
linenext = inband.ReadAsArray(0, i + 1, inband.XSize, 1, inband.XSize, 1)
for j in range(1, inband.XSize - 1):
dx = 2 * xsize
dzx = (linecur[0, j - 1] - linecur[0, j + 1]) * elstep
dy = 2 * ysize
dzy = (lineprev[0, j] - linenext[0, j]) * elstep
nx = -dy * dzx
ny = dx * dzy
nz = dx * dy
cosine = (nx*lx + ny*ly + nz*lz) / (sqrt(nx**2+ny**2+nz**2)*sqrt(lx**2+ly**2+lz**2))
if (cosine < 0):
outline[0, j] = 0.0
else:
outline[0, j] = cosine * 255
lineprev = linecur
linecur = linenext
outband.WriteArray(outline, 0, i)
# Display progress report on terminal
gdal.TermProgress(float(i + 1) / (inband.YSize - 1))
outdataset.SetGeoTransform(geotransform)
outdataset.SetProjection(projection)
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