- Grounding Line
U.S. NATIONAL ICE CENTER USNIC_ANTARC_shelf_2022
下載下來(lái)是shp文件窜护，里面坐標(biāo)系是WGS84的XY坐標(biāo)系。
要轉(zhuǎn)換為lon lat坐標(biāo)：
1）online
MyGeodata Converter
好處是很直接，壞處是一天可能最多只能免費(fèi)轉(zhuǎn)換一次
2）gdal — a translator library for raster and vector geospatial data formats
gdal里有個(gè)函數(shù)ogr2ogr專門用來(lái)轉(zhuǎn)換文件格式 比如shp轉(zhuǎn)成gmt之類的
ogr2ogr -f GMT -t_srs EPSG:4326 to.gmt from.shp
EPSG:4326就是WGS84 lon lat的代碼
詳細(xì)參考gdal ogr2ogr
GMT官方手冊(cè)上也有ogr2ogr
- Remote Sensing
EarthExplorer
下載Landsat8的RGB geotiff遙感圖像數(shù)據(jù)后婚苹，需要做一定的預(yù)處理才能用GMT繪制逻谦。參考了yangleir的博客粘拾。不過(guò)我的數(shù)據(jù)下載下來(lái)就是Byte格式的憔晒，只需要轉(zhuǎn)一下坐標(biāo)系就行了，從XY轉(zhuǎn)成latlon明吩。推薦下載數(shù)據(jù)后用gdalinfo命令看一下數(shù)據(jù)頭文件，有坐標(biāo)系殷费，投影印荔，范圍，波段之類的详羡。
gdalwarp -t_srs EPSG:4326 name.tif name_wgs.tif
GMT中：
+b0,1,2是按R仍律，G，B順序讀入數(shù)據(jù)并疊加实柠，畫(huà)出來(lái)的圖才正常水泉。另外-Q就是把-NaN的數(shù)據(jù)點(diǎn)都畫(huà)成透明的，不然就是黑色的窒盐，不方便兩張遙感圖像疊加草则。
R=74/78/-70/-68.5
J=M76.5/-69.5/12c
gmt begin 0104 pdf
gmt set FONT_ANNOT_PRIMARY 8p,Helvetica,black
gmt grdimage 0104_1.tif+b0,1,2 -J$J -Q
gmt grdimage 0104_2.tif+b0,1,2 -J$J -Q
gmt basemap -R$R -J$J -Baf -BSWNE -Lg77.25/-69.9+jBL+c-69.9+w20k+f+u
gmt end show
- Antarctica topography data
2-m spatial resolution: REMA
The file is a tiff dataset, with the coordinate of WGS 84 / Antarctic Polar Stereographic (EPSG:3031) (Unit: m). Thus, I first use gdal to convert it to WGS 84/4326:
gdalwarp -s_srs EPSG:3031 -t_srs EPSG:4326 36_52_1_2_2m_v2.0_dem.tif REMA.nc
Or the pixel size can be given:
gdalwarp -tr 0.000045 0.000045 -s_srs EPSG:3031 -t_srs EPSG:4326 36_52_1_2_2m_v2.0_dem.tif REMA.nc # -tr dx dy (Unit: degree)
- lon, lat 2 utm (Universal Transverse Mercator, a specific coordinate system commonly used in California)
import pyproj
nad27utm = pyproj.Proj(proj="utm", zone='11', datum='WGS84', ellps='WGS84', preserve_unites=False)
M1 = (-117.504, 35.705, 10.5); M2 = (-117.599, 35.770, 8.0)
M1_x, M1_y = nad27utm(M1[0], M1[1])
