SRTM高程数据处理¶
从USGS下载数据。¶
In [1]:
!wget -c http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/Africa/N00E018.hgt.zip -O ../data/N00E018.hgt.zip
--2016-05-04 14:12:03-- http://dds.cr.usgs.gov/srtm/version2_1/SRTM3/Africa/N00E018.hgt.zip
正在解析主机 dds.cr.usgs.gov (dds.cr.usgs.gov)... 152.61.133.66, 2001:49c8:4000:124c::66
正在连接 dds.cr.usgs.gov (dds.cr.usgs.gov)|152.61.133.66|:80... 已连接。
已发出 HTTP 请求,正在等待回应... 200 OK
长度: 896459 (875K) [application/zip]
正在保存至: “N00E018.hgt.zip”
N00E018.hgt.zip 100%[===================>] 875.45K 16.2KB/s in 98s
2016-05-04 14:13:48 (8.89 KB/s) - 已保存 “N00E018.hgt.zip” [896459/896459])
解压缩得到 *.hgt 文件。¶
In [2]:
!unzip ../data/N00E018.hgt.zip
Archive: N00E018.hgt.zip
inflating: N00E018.hgt
(二)数据格式和投影转换。¶
将 *.hgt 转为 GeoTiff。 使用GDAL(http://www.gdal.org) 进行转换。¶
In [3]:
!gdal_translate -of GTiff -co "TILED=YES" -a_srs "+proj=latlong" ../data/N00E018.hgt ../data/N00E018_adapted.tif
Input file size is 1201, 1201
0...10...20...30...40...50...60...70...80...90...100 - done.
地理投影转换。¶
In [4]:
!gdalwarp -of GTiff -co "TILED=YES" -srcnodata 32767 -t_srs "+proj=merc +ellps=sphere +R=6378137 \
+a=6378137 +units=m" -rcs -order 3 -tr 30 30 -multi N00E018_adapted.tif N00E018_warped.tif
Creating output file that is 3714P x 3714L.
Processing input file N00E018_adapted.tif.
Copying nodata values from source N00E018_adapted.tif to destination N00E018_warped.tif.
0...10...20...30...40...50...60...70...80...90...100 - done.
(三)立体效果渲染。¶
从DEM生成Hillshade。¶
In [5]:
!gdaldem hillshade ../data/N00E018_warped.tif ../data/N00E018_hillshade.tif
0...10...20...30...40...50...60...70...80...90...100 - done.
(四)生成等高线。¶
使用GDAL生成25米等高距的等高线,输出shp格式。¶
In [7]:
!gdal_contour -a elev ../data/N00E018_adapted.tif ../data/N00E018_contour25.shp -i 25.0
0...10...20...30...40...50...60...70...80...90...100 - done.
查看生成的文件目录。¶
In [1]:
!ls -l -h ../data/
总用量 13M
-rw-rw-r-- 1 supermap supermap 5.6M 5月 4 13:44 GIScript_Test.udb
-rw-r--r-- 1 supermap supermap 74K 5月 4 13:44 GIScript_Test.udd
drwxrwxr-x 2 supermap supermap 4.0K 8月 13 2015 Grid
-rw-r--r-- 1 supermap supermap 2.8M 1月 15 2009 N00E018.hgt
-rw-rw-r-- 1 supermap supermap 876K 7月 22 2009 N00E018.hgt.zip
drwxrwxr-x 2 supermap supermap 4.0K 5月 8 22:50 nybb_16a
-rw-rw-r-- 1 supermap supermap 645K 2月 29 22:44 nybb_16a.zip
drwxrwxr-x 2 supermap supermap 4.0K 5月 4 16:04 osm
-rw-rw-r-- 1 supermap supermap 10 5月 4 15:17 osm_test.cpg
-rw-rw-r-- 1 supermap supermap 5.8K 5月 4 15:17 osm_test.dbf
-rw-rw-r-- 1 supermap supermap 2.7M 5月 4 15:00 osm_test.osm
-rw-rw-r-- 1 supermap supermap 380 5月 4 15:17 osm_test.shp
-rw-rw-r-- 1 supermap supermap 180 5月 4 15:17 osm_test.shx
-rw-rw-r-- 1 supermap supermap 131K 5月 4 15:27 overpass.osm_node.json
drwxrwxr-x 2 supermap supermap 4.0K 8月 11 2015 Raster
drwxrwxr-x 2 supermap supermap 4.0K 7月 31 2015 Shape
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