gdal用法总结

USAGE OF GDAL RASTER API

Import gdal
from osgeo import gdal

Open the file

Dataset=gdal.Open(filename)

Getting dataset information

Xsize=dataset.RasterXsize
Ysize=dataset.RasterYSize
Count=dataset.RasterCount
Geotransform=dataset.GetGeoTransform()
Pro=dataset.GetProjection()

Fetching a raster band

band=dataset.GetRasterBand(1)
type=gdal.GetDataTypeName(band.DataType)
min=band.GetMinimum()
max=band.GetMaximum()
if not min or not max:
    (min,max)=band.ComputeRasterMinMax(True)

Reading raster data

scanline=band.ReadRaster(xoff=0,yoff=0,xsize=band.XSize,ysize=1,buf_xsize=band.XSize,buf_ysize=1,buf_type=gdal.GDT_Float32)
import struct
tuple_of_floats=struct.unpack(‘f’*band.XSize,scanline)

CreatCopy

driver=src_ds.GetDriver()
dst_ds=driver.CreateCopy(dst_filename,src_ds,strict=0)

Create

dst_ds=driver.Create(dst_filename,xsize=512,ysize=512,bands=1,eType=gdal.GDT_Byte)

Set dataset transform and projection

from osgeo import osr
dst_ds.SetGeoTransform([444720,30,0,375130,0,-30])
srs=osr.SpatialReference()
srs.importFromEPSG(4326)
dst_ds.SetProjection(srs.ExportToWkt())

set dataset value

import numpy
raster=numpy.zeros((512,512),dtype=numpy.uint8)
dst_ds.GetRasterBand(1).WriteArray(raster)

Close the dataset

dst_ds=None

USAGE OF GDAL VECTOR API

Import ogr
from osgeo import ogr

Open the file

dataset=ogr.Open(filename)
driver=dataset.GetDriver()

Getting Layer

count=dataset.GetLayerCount()
lyr=dataset.GetLayer(i)
lyr2=dataset.GetLayer(‘layername’)

Getting layer information

extent=lyr.GetExtent()
geom_type=lyr.GetGeomType()
ref=lyr.GetSpatialRef()
lyrname=lyr.GetName()
feature_all=lyr.GetFeatureCount()
schema=lyr.schema
for field in schema:
    print(field.name,field.GetTypeName())

Getting feature

fea=lyr.GetFeature(index)

Getting feature information

geo=fea.geometry()
field_value=fea.GetFiled(filedname)
field_value=fea.GetFieldAsString(fieldname)
field_value=fea.GetFieldAsDouble(filedname)
field_count=fea.GetFieldCount()

Getting geometry information

point_count=line.GetPointCount()
x_0=line.GetX(0)
y_0=line.GetY(0)
ring=polygon.GetGeometryRef(0)

Create

drive=ogr.GetDriverByName(‘ESRI Shapefile’)
dataset=driver.CreateDataSource(filename)
layer=dataset.CreateLayer(name)
fieldDefn=ogr.FieldDefn(‘id’,ogr.OFTString)
fieldDefn.SetWidth(4)
layer.CreateField(fieldDefn)
featureDefn=layer.GetLayerDefn()
feature=ogr.Feature(featureDefn)
feature.SetGeometry(geometry)
feature.SetField(‘id’,23)
layer.CreateFeature(feature)

Setting geometry information

point=ogr.Geometry(ogr.wkbPoint)
point.AddPoint(10,20)
line=ogr.Geometry(ogr.wkbLineString)
line.AddPoint(10,20)
line.AddPoint(10,20)
line.SetPoint(1,50,50)
ring=ogr.Geometry(ogr.wkbLineRing)
ring.AddPoint(10,10)
ring.AddPoint(50,0)
ring.AddPoint(50,50)
ring.CloseRings()
polygon=ogr.Geometry(ogr.wkbPolygon)
polygon.AddGeometry(outring)
polygon.AddGeometry(inring)

Delete

Driver.DeleteDataSource(filename)

USAGE OF GDAL SCRIPTS
gdallocationinfo.exe

gdallocationinfo.exe N27E088.hgt -wgs84 88.2123 27.1115

gdalinfo.exe

gdalinfo.exe –proj4 rec.tif

gdalwarp.exe

gdalwarp.exe [-s_srs srs_def] [-t_srs srs_def] [-ot Byte/Int16/...] [-srcnodata "value [value...]"] [-dstnodata "value [value...]"] [-of format] [-co "NAME=VALUE"] srcfile dstfile

gdal_translate.exe

gdal_translate.exe rec.tif my.tif –b 1 –outsize 300 300

gdal_merge.exe

gdal_merge.exe -o output.tif srtm_56_07.tif srtm_57_07.tif

gdal_contour.exe

gdal_contour.exe –a elev dem.tif countor.shp –i 10.0

gdal2tiles.py

Python gdal2tiles.py –p mercator –z 0-5 –w none image dir