def create_contours(input_path,
spacing,
shp_path="DEFAULT",
contour_base=0,
no_data=1,
no_data_value=0,
overwrite=False):
"""
adapted from: http://stackoverflow.com/questions/22100453/gdal-python-creating-contourlines
"""
if shp_path == "DEFAULT":
shp_path = input_path[:-4] + '_contour.shp'
if os.path.isfile(shp_path) and overwrite != True:
print "\n Contour lines already exist: {} \nProceeding with next file without checking for varying parameters (e.g. contour line spacing).\n Force overwrite with overwrite=True...".format(
shp_path)
return shp_path
try:
#Read in SRTM data
raster = gdal.Open(input_path, GA_ReadOnly)
raster_band1 = raster.GetRasterBand(1)
#Generate layer to save Contourlines in
contour_ds = ogr.GetDriverByName("ESRI Shapefile").CreateDataSource(
shp_path)
contour_shp = contour_ds.CreateLayer('contour')
field_defn = ogr.FieldDefn("ID", ogr.OFTInteger)
contour_shp.CreateField(field_defn)
field_defn = ogr.FieldDefn("height", ogr.OFTReal)
contour_shp.CreateField(field_defn)
#TODO create nth field here
#Generate Contourlines
# gdal.ContourGenerate(raster_band1,spacing,contourbase,fixedlevelcount,boleanusenodata,dfnodatavalue,hLayer,idField,iElevfield,progress,pProgressArg
# http://www.gdal.org/gdal__alg_8h.html#aceaf98ad40f159cbfb626988c054c085
gdal.ContourGenerate(raster_band1, spacing, contour_base, [], no_data,
no_data_value, contour_shp, 0, 1)
# TODO: delete small features < 1000m
# more info here: http://pcjericks.github.io/py-gdalogr-cookbook/layers.html#filter-and-select-input-shapefile-to-new-output-shapefile-like-ogr2ogr-cli
contour_ds = None
del contour_ds
return shp_path
pass
except Exception as e:
print "createContours() could not finish it's duty Sir!"
raise
def grid_contour(source, target):
'''grid_contour() - Use GDAL and OGR to create a contour shapefile
Parameters
----------
source : str
input shapefile name
target : str
output shapefile name
Returns
-------
nothing
'''
import ogr as ogr
import gdal as gdal
if target[-4:] != '.shp':
target += '.shp'
ogr_driver = ogr.GetDriverByName('ESRI Shapefile')
ogr_ds = ogr_driver.CreateDataSource(target)
ogr_lyr = ogr_ds.CreateLayer(target, geom_type=ogr.wkbLineString25D)
field_defn = ogr.FieldDefn('ID', ogr.OFTInteger)
ogr_lyr.CreateField(field_defn)
field_defn = ogr.FieldDefn('ELEV', ogr.OFTReal)
ogr_lyr.CreateField(field_defn)
# gdal.ContourGenerate() arguments:
# Band srcBand,
# double contourInterval,
# double contourBase,
# double[] fixedLevelCount,
# int useNoData,
# double noDataValue,
# Layer dstLayer,
# int idField,
# int elevField
ds = gdal.Open(source)
gdal.ContourGenerate(ds.GetRasterBand(1), 400, 10, [], 0, 0, ogr_lyr, 0, 1)
return
def counter(tiff_file, line_file):
"""生成等值线
:param tiff_file:栅格数据
:param line_file: 等值线结果
:return:
"""
indataset1 = gdal.Open(tiff_file, gdal.GA_ReadOnly)
in1 = indataset1.GetRasterBand(1)
#Generate layer to save Contourlines in
ogr_ds = ogr.GetDriverByName("ESRI Shapefile").CreateDataSource(line_file)
srs = osr.SpatialReference()
srs.ImportFromEPSG(4326)
contour_shp = ogr_ds.CreateLayer('contour', srs)
field_defn = ogr.FieldDefn("ID", ogr.OFTInteger)
contour_shp.CreateField(field_defn)
field_defn = ogr.FieldDefn("elev", ogr.OFTReal)
contour_shp.CreateField(field_defn)
#Generate Contourlines
gdal.ContourGenerate(in1, 1, 0, [], 0, 0, contour_shp, 0, 1)
ogr_ds.Destroy()
import gdal
import ogr
# Elevation DEM
source = "dem.asc"
# Output shapefile
target = "contour"
ogr_driver = ogr.GetDriverByName('ESRI Shapefile')
ogr_ds = ogr_driver.CreateDataSource(target + ".shp")
ogr_lyr = ogr_ds.CreateLayer(target, geom_type=ogr.wkbLineString25D)
field_defn = ogr.FieldDefn('ID', ogr.OFTInteger)
ogr_lyr.CreateField(field_defn)
field_defn = ogr.FieldDefn('ELEV', ogr.OFTReal)
ogr_lyr.CreateField(field_defn)
# gdal.ContourGenerate() arguments
# Band srcBand,
# double contourInterval,
# double contourBase,
# double[] fixedLevelCount,
# int useNoData,
# double noDataValue,
# Layer dstLayer,
# int idField,
# int elevField
ds = gdal.Open('dem.asc')
gdal.ContourGenerate(ds.GetRasterBand(1), 400, 10, [], 0, 0, ogr_lyr, 0, 1)
time_step = 0
for k in np.arange(0, src_ds.RasterCount):
if tdim is None:
timestamp = "0-0-0"
else:
timestamp = timestamps[k]
logger.info("Processing {}".format(timestamp))
srcband = src_ds.GetRasterBand(k + 1)
logger.debug("Running gdal.ContourGenerate()")
tmp_layer = create_memory_layer(dst_fieldname)
result = gdal.ContourGenerate(srcband,
0,
0,
levels,
0,
0,
tmp_layer,
0,
1,
callback=gdal.TermProgress)
logger.info("Saving results")
featureDefn = interface_layer.GetLayerDefn()
for feature in tmp_layer:
# create a new feature
outFeature = ogr.Feature(featureDefn)
outFeature.SetGeometry(feature.GetGeometryRef())
i = outFeature.GetFieldIndex("level")
ik = feature.GetFieldIndex("level")
outFeature.SetField(i, feature.GetField(ik))
i = outFeature.GetFieldIndex("timestep")
def contour_1():
try:
os.remove('tmp/contour.shp')
except:
pass
try:
os.remove('tmp/contour.dbf')
except:
pass
try:
os.remove('tmp/contour.shx')
except:
pass
drv = gdal.GetDriverByName('GTiff')
wkt = 'GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9108\"]],AUTHORITY[\"EPSG\",\"4326\"]]'
size = 160
precision = 1. / size
ds = drv.Create('tmp/gdal_contour.tif', size, size, 1)
ds.SetProjection(wkt)
ds.SetGeoTransform([1, precision, 0, 50, 0, -precision])
raw_data = array.array('h', [10 for i in range(int(size / 2))]).tostring()
for i in range(int(size / 2)):
ds.WriteRaster(int(size / 4),
i + int(size / 4),
int(size / 2),
1,
raw_data,
buf_type=gdal.GDT_Int16,
band_list=[1])
raw_data = array.array('h', [20 for i in range(int(size / 2))]).tostring()
for i in range(int(size / 4)):
ds.WriteRaster(int(size / 4) + int(size / 8),
i + int(size / 4) + int(size / 8),
int(size / 4),
1,
raw_data,
buf_type=gdal.GDT_Int16,
band_list=[1])
raw_data = array.array('h', [25 for i in range(int(size / 4))]).tostring()
for i in range(int(size / 8)):
ds.WriteRaster(int(size / 4) + int(size / 8) + int(size / 16),
i + int(size / 4) + int(size / 8) + int(size / 16),
int(size / 8),
1,
raw_data,
buf_type=gdal.GDT_Int16,
band_list=[1])
ogr_ds = ogr.GetDriverByName('ESRI Shapefile').CreateDataSource(
'tmp/contour.shp')
ogr_lyr = ogr_ds.CreateLayer('contour')
field_defn = ogr.FieldDefn('ID', ogr.OFTInteger)
ogr_lyr.CreateField(field_defn)
field_defn = ogr.FieldDefn('elev', ogr.OFTReal)
ogr_lyr.CreateField(field_defn)
gdal.ContourGenerate(ds.GetRasterBand(1), 10, 0, [], 0, 0, ogr_lyr, 0, 1)
ds = None
expected_envelopes = [[1.25, 1.75, 49.25, 49.75],
[
1.25 + 0.125, 1.75 - 0.125, 49.25 + 0.125,
49.75 - 0.125
]]
expected_height = [10, 20]
lyr = ogr_ds.ExecuteSQL("select * from contour order by elev asc")
if lyr.GetFeatureCount() != len(expected_envelopes):
print('Got %d features. Expected %d' %
(lyr.GetFeatureCount(), len(expected_envelopes)))
return 'fail'
i = 0
feat = lyr.GetNextFeature()
while feat is not None:
envelope = feat.GetGeometryRef().GetEnvelope()
if feat.GetField('elev') != expected_height[i]:
print('Got %f. Expected %f' %
(feat.GetField('elev'), expected_height[i]))
return 'fail'
for j in range(4):
if abs(expected_envelopes[i][j] -
envelope[j]) > precision / 2 * 1.001:
print('i=%d, wkt=%s' %
(i, feat.GetGeometryRef().ExportToWkt()))
print(feat.GetGeometryRef().GetEnvelope())
print(expected_envelopes[i])
print('%f, %f' %
(expected_envelopes[i][j] - envelope[j], precision / 2))
return 'fail'
i = i + 1
feat = lyr.GetNextFeature()
ogr_ds.ReleaseResultSet(lyr)
ogr_ds.Destroy()
return 'success'
def contour_2():
try:
os.remove('tmp/contour.shp')
except:
pass
try:
os.remove('tmp/contour.dbf')
except:
pass
try:
os.remove('tmp/contour.shx')
except:
pass
ogr_ds = ogr.GetDriverByName('ESRI Shapefile').CreateDataSource(
'tmp/contour.shp')
ogr_lyr = ogr_ds.CreateLayer('contour', geom_type=ogr.wkbLineString25D)
field_defn = ogr.FieldDefn('ID', ogr.OFTInteger)
ogr_lyr.CreateField(field_defn)
field_defn = ogr.FieldDefn('elev', ogr.OFTReal)
ogr_lyr.CreateField(field_defn)
ds = gdal.Open('tmp/gdal_contour.tif')
gdal.ContourGenerate(ds.GetRasterBand(1), 0, 0, [10, 20, 25], 0, 0,
ogr_lyr, 0, 1)
ds = None
size = 160
precision = 1. / size
expected_envelopes = [[1.25, 1.75, 49.25, 49.75],
[
1.25 + 0.125, 1.75 - 0.125, 49.25 + 0.125,
49.75 - 0.125
],
[
1.25 + 0.125 + 0.0625, 1.75 - 0.125 - 0.0625,
49.25 + 0.125 + 0.0625, 49.75 - 0.125 - 0.0625
]]
expected_height = [10, 20, 25]
lyr = ogr_ds.ExecuteSQL("select * from contour order by elev asc")
if lyr.GetFeatureCount() != len(expected_envelopes):
print('Got %d features. Expected %d' %
(lyr.GetFeatureCount(), len(expected_envelopes)))
return 'fail'
i = 0
feat = lyr.GetNextFeature()
while feat is not None:
if feat.GetGeometryRef().GetZ(0) != expected_height[i]:
print('Got %f as z. Expected %f' %
(feat.GetGeometryRef().GetZ(0), expected_height[i]))
return 'fail'
envelope = feat.GetGeometryRef().GetEnvelope()
if feat.GetField('elev') != expected_height[i]:
print('Got %f. Expected %f' %
(feat.GetField('elev'), expected_height[i]))
return 'fail'
for j in range(4):
if abs(expected_envelopes[i][j] -
envelope[j]) > precision / 2 * 1.001:
print('i=%d, wkt=%s' %
(i, feat.GetGeometryRef().ExportToWkt()))
print(feat.GetGeometryRef().GetEnvelope())
print(expected_envelopes[i])
print('%f, %f' %
(expected_envelopes[i][j] - envelope[j], precision / 2))
return 'fail'
i = i + 1
feat = lyr.GetNextFeature()
ogr_ds.ReleaseResultSet(lyr)
ogr_ds.Destroy()
return 'success'