python地图投影转换

Posted 2022-12-06 ninicwang

一、投影包osr与proj4的使用

1.osr投影转换示例

from osgeo import osr,ogr
#定义投影
#wgs84
source=osr.SpatialReference()
source.ImportFromEPSG(4326)
#google
target=osr.SpatialReference()
target.ImportFromEPSG(3857)
#简单投影转换
coordTrans=osr.CoordinateTransformation(source,target)
#点转换
coordTrans.TransformPoint(117,40)
#点数组转换
coordTrans.TransformPoints([(117,40),(117.5,39.5)])
#SF几何对象转换
g=ogr.CreateGeometryFromWkt("POINT(117 40)")
#转换前wgs84
print(g.ExportToWkt())
print(g.GetX(),g.GetY())
#转换后google
g.Transform(coordTrans)
print(g.ExportToWkt())
print(g.GetX(),g.GetY())
2.投影转换示例

from pyproj import Proj,Geod,transform
# projection 1: UTM zone 15, grs80 ellipse, NAD83 datum
# (defined by epsg code 26915)
p1 = Proj(init=‘epsg:26915‘)
# projection 2: UTM zone 15, clrk66 ellipse, NAD27 datum
p2 = Proj(init=‘epsg:26715‘)
#点的转换(首先将地理坐标转换成p1投影坐标系下的平面直角坐标，再将x1,y1转换到p2投影坐标系下，最后将p2投影坐标系下的平面直角坐标转换成地理坐标)
x1,y1=p1(-92.199881,38.56694)
x2, y2 = transform(p1,p2,x1,y1)
print(‘%9.3f %11.3f‘ % (x1,y1))
print(‘%9.3f %11.3f‘ % (x2,y2))
print(‘%8.3f %5.3f‘ % p2(x2,y2,inverse=True))
#点数组的转换
lats = (38.83,39.32,38.75)
lons = (-92.22,-94.72,-90.37)
x1,y1=p1(lons,lats)
x2,y2=transform(p1,p2,x1,y1)
xy=x1+y1
print(‘%9.3f %9.3f %9.3f %11.3f %11.3f %11.3f‘ % xy)
xy=x2+y2
print(‘%9.3f %9.3f %9.3f %11.3f %11.3f %11.3f‘ % xy)
lons, lats = p2(x2,y2,inverse=True)
xy=lons+lats
print(‘%8.3f %8.3f %8.3f %5.3f %5.3f %5.3f‘ % xy)
p1 = Proj(proj=‘latlong‘,datum=‘WGS84‘)
x1 = -111.5; y1 = 45.25919444444
p2 = Proj(proj="utm",zone=10,datum=‘NAD27‘)
x2, y2 = transform(p1, p2, x1, y1)
print("%s %s" % (str(x2)[:9],str(y2)[:9]))

二、栅格数据投影转换

#栅格数据投影转换
from osgeo import gdal,osr
from osgeo.gdalconst import *
#源图像投影
source=osr.SpatialReference()
source.ImportFromEPSG(32650)
#目标图像投影
target=osr.SpatialReference()
target.ImportFromEPSG(3857)
coordTrans=osr.CoordinateTransformation(source,target)
#打开源图像文件
ds=gdal.Open("fdem.tif")
#仿射矩阵六参数
mat=ds.GetGeoTransform()
#源图像的左上角与右下角像素，在目标图像中的坐标
(ulx, uly, ulz)=coordTrans.TransformPoint(mat[0],mat[3])
(lrx, lry, lrz ) = coordTrans.TransformPoint(mat[0] + mat[1]*ds.RasterXSize, mat[3] + mat[5]* ds.RasterYSize )
#创建目标图像文件（空白图像），行列数、波段数以及数值类型仍等同原图像
driver=gdal.GetDriverByName("GTiff")
ts=driver.Create("fdem_lonlat.tif",ds.RasterXSize,ds.RasterYSize,1,GDT_UInt16)
#转换后图像的分辨率
resolution=(int)((lrx-ulx)/ds.RasterXSize)
#转换后图像的六个放射变换参数
mat2=[ulx, resolution,0,uly,0, -resolution]
ts.SetGeoTransform(mat2)
ts.SetProjection(target.ExportToWkt())
#投影转换后需要做重采样
gdal.ReprojectImage(ds, ts, source.ExportToWkt(), target.ExportToWkt(), gdal.GRA_Bilinear)
#关闭
ds = None
ts= None