我有幾個多邊形&我喜歡從這些多邊形內的幾個柵格圖層中提取平均值。 當我將這些添加到ArcMap時,我意識到兩種數據類型的投影不匹配。我可以通過使用項目工具(數據管理工具箱>投影和轉換工具集>柵格)來解決ArcGIS中顯示的問題。所以,我試圖通過將數據加載成R以下面的方式(該代碼的一部分)以規範的投影:R中柵格和多邊形的座標參考系統
柵格:
for (i in 1:length(rasterlist1))
{ndvi_raster_stack1[i]<-raster(rasterlist1[i])
raster::NAvalue(ndvi_raster_stack1[[i]])<--999
projection(ndvi_raster_stack1[[i]])<-"+proj=utm +ellps=WGS84 +datum=WGS84 +units=m"}
> ndvi_raster_stack1[[1]]
class : RasterLayer
dimensions : 226, 150, 33900 (nrow, ncol, ncell)
resolution : 0.57504, 0.5753628 (x, y)
extent : -28.728, 57.528, -55.08, 74.952 (xmin, xmax, ymin, ymax)
coord. ref. : +proj=utm +ellps=WGS84 +datum=WGS84 +units=m +towgs84=0,0,0
values : Z:\master\lusmeg_sw_kernel_data\ndvi0910\Y2008_P47.tif
min value : -91
max value : 550.8125
多邊形:
for (i in 1:length(poplist))
{pop_kernels[i]<-readShapeSpatial(poplist[i],repair=TRUE,proj4string=CRS("+proj=utm +ellps=WGS84 +datum=WGS84 +units=m"))
pop_kernels[[i]]<-unionSpatialPolygons(pop_kernels[[i]],ID=c(rep(1,times=length(pop_kernels[[i]])-1),0),threshold=NULL,avoidGEOS=FALSE)}
> str(pop_kernels[[1]])
Formal class 'SpatialPolygons' [package "sp"] with 4 slots
[email protected] polygons :List of 2
.. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
.. .. .. [email protected] Polygons :List of 2
.. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
.. .. .. .. .. .. [email protected] labpt : num [1:2] 2404422 893343
.. .. .. .. .. .. [email protected] area : num 1.15e+12
.. .. .. .. .. .. [email protected] hole : logi FALSE
.. .. .. .. .. .. [email protected] ringDir: int 1
.. .. .. .. .. .. [email protected] coords : num [1:1625, 1:2] 2551236 2533236 2533236 2523236 2523236 ...
.. .. .. .. .. .. .. ..- attr(*, "dimnames")=List of 2
.. .. .. .. .. .. .. .. ..$ : NULL
.. .. .. .. .. .. .. .. ..$ : chr [1:2] "x" "y"
.. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
.. .. .. .. .. .. [email protected] labpt : num [1:2] 2468549 865776
.. .. .. .. .. .. [email protected] area : num 6.31e+11
.. .. .. .. .. .. [email protected] hole : logi TRUE
.. .. .. .. .. .. [email protected] ringDir: int -1
.. .. .. .. .. .. [email protected] coords : num [1:1385, 1:2] 2551236 2551236 2563236 2563236 2569236 ...
.. .. .. .. .. .. .. ..- attr(*, "dimnames")=List of 2
.. .. .. .. .. .. .. .. ..$ : NULL
.. .. .. .. .. .. .. .. ..$ : chr [1:2] "x" "y"
.. .. .. [email protected] plotOrder: int [1:2] 1 2
.. .. .. [email protected] labpt : num [1:2] 2404422 893343
.. .. .. [email protected] ID : chr "0"
.. .. .. [email protected] area : num 1.15e+12
.. ..$ :Formal class 'Polygons' [package "sp"] with 5 slots
.. .. .. [email protected] Polygons :List of 1
.. .. .. .. ..$ :Formal class 'Polygon' [package "sp"] with 5 slots
.. .. .. .. .. .. [email protected] labpt : num [1:2] 2468549 865776
.. .. .. .. .. .. [email protected] area : num 6.31e+11
.. .. .. .. .. .. [email protected] hole : logi FALSE
.. .. .. .. .. .. [email protected] ringDir: int 1
.. .. .. .. .. .. [email protected] coords : num [1:1385, 1:2] 2551236 2541236 2541236 2529236 2529236 ...
.. .. .. .. .. .. .. ..- attr(*, "dimnames")=List of 2
.. .. .. .. .. .. .. .. ..$ : NULL
.. .. .. .. .. .. .. .. ..$ : chr [1:2] "x" "y"
.. .. .. [email protected] plotOrder: int 1
.. .. .. [email protected] labpt : num [1:2] 2468549 865776
.. .. .. [email protected] ID : chr "1"
.. .. .. [email protected] area : num 6.31e+11
[email protected] plotOrder : int [1:2] 1 2
[email protected] bbox : num [1:2, 1:2] 1819236 207017 3013236 1577017
.. ..- attr(*, "dimnames")=List of 2
.. .. ..$ : chr [1:2] "x" "y"
.. .. ..$ : chr [1:2] "min" "max"
[email protected] proj4string:Formal class 'CRS' [package "sp"] with 1 slots
.. .. [email protected] projargs: chr " +proj=utm +ellps=WGS84 +datum=WGS84 +units=m +towgs84=0,0,0"
我可以繪製多邊形和柵格分開,但是當我嘗試在柵格上繪製其中一個多邊形時,多邊形不會顯示:
plot(ndvi_raster_stack1[[1]],xlab="Longitude",ylab="Latitude")
plot(pop_kernels[[1]],col="black",add=TRUE)
看來他們還是沒有「重疊」。這也是由不同的邊框表示,我認爲:
> bbox(ndvi_raster_stack1[[1]])
min max
s1 -28.728 57.528
s2 -55.080 74.952
> bbox(pop_kernels[[1]])
min max
x 1819236 3013236
y 207017 1577017
因爲我想多邊形中提取柵格值,我必須確保他們以正確的方式引用。 有人有一個想法可能是什麼問題?