[英]Converting raster stack extent from meters to lat/lon coordinates
I have a raster stack in the following format which I converted to NetCDF using this method . 我有以下格式的栅格堆栈,我使用此方法将其转换为NetCDF 。 This works but the latitude and longitude variables are in 'meters' which is the extent of the raster file, and I need them to be in decimal degrees.
此方法有效,但是纬度和经度变量在“米”中,这是栅格文件的范围,我需要将它们设置为十进制度。 The R Grid file is here and the format is as follows:
R Grid文件在这里 ,格式如下:
class : RasterBrick
dimensions : 205, 170, 34850, 12 (nrow, ncol, ncell, nlayers)
resolution : 1, 1 (x, y)
extent : 160.5, 330.5, 145.5, 350.5 (xmin, xmax, ymin, ymax)
coord. ref. : NA
data source : \TavgM_1981.grd
names : Jan.1981, Feb.1981, Mar.1981, Apr.1981, May.1981, Jun.1981, Jul.1981, Aug.1981, Sep.1981, Oct.1981, Nov.1981, Dec.1981
min values : 1.9912137, 0.8120775, 4.0446638, 4.4135274, 6.5349769, 8.6149150, 9.9991916, 11.8400562, 9.6407796, 3.5005649, 4.1205872, -0.6106244
max values : 9.850221, 9.121176, 10.238524, 9.858942, 11.669445, 14.260988, 15.722292, 17.235090, 15.708690, 11.598482, 11.552235, 8.981533
time : Jan 1981, Feb 1981, Mar 1981, Apr 1981, May 1981, Jun 1981, Jul 1981, Aug 1981, Sep 1981, Oct 1981, Nov 1981, Dec 1981
Ideally I would like to convert this to a NetCDF file which has the following format to be read by a model: 理想情况下,我想将其转换为NetCDF文件,该文件具有以下格式,可供模型读取:
Dimensions: (lat: 408, lon: 881, nb2: 2, time: 660)
Coordinates:
* lon (lon) float64 -44.81 -44.69 -44.56 -44.44 -44.31 -44.19 ...
* lat (lat) float64 21.81 21.94 22.06 22.19 22.31 22.44 22.56 22.69 ...
* time (time) datetime64[ns] 1951-01-16T12:00:00 1951-02-16T12:00:00 ...
Dimensions without coordinates: nb2
Data variables:
time_bnds (time, nb2) datetime64[ns] 1951-01-16T12:00:00 ...
tas (time, lat, lon) float64 nan nan nan nan nan nan nan nan nan ...
I tried to convert the Raster Brick extent to lat/lon using this method: 我尝试使用此方法将Raster Brick范围转换为lat / lon:
sputm <- SpatialPoints(test@extent@xmin, proj4string=CRS("+proj=utm +zone=29N +datum=WGS84"))
But this gives this error: 但这给出了这个错误:
Error in (function (classes, fdef, mtable) : unable to find an inherited method for function ‘coordinates’ for signature ‘"numeric"’
EDIT: Also tried 编辑:也尝试过
crs(test) <- '+proj=merc +datum=WGS84'
x <- projectRaster(test, crs='+proj=longlat +datum=WGS84')
writeRaster(x, "rstack2.nc", overwrite=TRUE, format="CDF", varname="Temperature", varunit="degC",
longname="Temperature -- raster stack to netCDF", xname="Longitude", yname="Latitude", zname="Time (Month)")
But when I examine this in panoply the lat and lon coordinates are all 0.0. 但是,当我全景查看时,纬度和经度坐标均为0.0。
I'm not sure where to go from here. 我不确定从这里去哪里。
As fas as I recognized Ireland, I looked at Ireland projections. 当我认识到爱尔兰时,我一直关注爱尔兰的预测。 I think this is the TM75 / Irish Grid.
我认为这是TM75 /爱尔兰网格。 I modified the resolution of your raster so that it is 2500m.
我修改了栅格的分辨率,使其为2500m。
library(raster)
r <- stack("~/Bureau/TavgM_1981")
xmax(r) <- xmin(r) + 2500 * ncol(r)
ymax(r) <- ymin(r) + 2500 * nrow(r)
crs(r) <- "+proj=tmerc +lat_0=53.5 +lon_0=-8 +k=1.000035 +x_0=200000 +y_0=250000 +ellps=mod_airy +towgs84=482.5,-130.6,564.6,-1.042,-0.214,-0.631,8.15 +units=m +no_defs"
# Convert to degrees
x_wgs84 <- projectRaster(r, crs='+proj=longlat +datum=WGS84')
writeRaster(x, "~/Bureau/TavgM_wgs84.tif", overwrite = TRUE)
You will see below the result of this resolution + projection modification compared to the target. 您将在下面看到与目标相比该分辨率+投影修改的结果。
We are not so far from reality but there is something bad in your original raster. 我们离现实不远,但是您原始的栅格中有一些不好的东西。 If this is (unfortunately) usual not to have the crs when somebody gives you a layer, this is not usual to miss the correct resolution.
如果在某人给您一个图层时这(不幸的是)通常不具有crs,则通常不会错过正确的分辨率。
As the raster you provide is saved as ".gri/.grd" file, this means that it has been produced with R. You should try to get the original R code that produced the file, instead of the final modified layer. 由于您提供的栅格将另存为“ .gri / .grd”文件,这意味着它是使用R生成的。您应该尝试获取生成该文件的原始R代码,而不是最终的修改层。
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