Created
October 1, 2016 22:07
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spatial_rotation.R
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library(data.table) | |
library(sp) | |
library(ggplot2) | |
library(broom) | |
library(gridExtra) | |
set.seed(1) | |
# Set-up Dummy Data (for example) | |
n <- | |
data3D <- data.table(merge(data.frame(x = runif(n,min = 504007.5,max=504874.9),y = runif(n,min=6251663.6,max=6252643.0)),data.frame(z = seq(0,1,by=1)))) | |
data3D[,avg_phie:=rnorm(1,mean = 0.30,sd = 0.02),by=c("x","y")] | |
data3D[,avg_swe:=rnorm(1,mean = 0.27,sd = 0.04),by=c("x","y")] | |
data3D[,avg_h:=runif(1,min=0,max=50)*(1-0.2)+0.2,by=c("x","y")] | |
data3D[,phie:=rnorm(.N,mean=avg_phie,sd=0.02),by=c("x","y")] | |
data3D[,swe:=rnorm(.N,mean=avg_swe,sd=0.04),by=c("x","y")] | |
data3D[z>avg_h,phie:=0,] | |
data3D <- data.frame(subset(data3D,select=c(x,y,z,phie,swe))) | |
coordinates(data3D) = ~x+y+z | |
# Set Projection so we can rotate from here! | |
#proj4string(data3D) <- "+proj=utm +zone=12 +ellps=GRS80 +datum=NAD83 +units=m +no_defs" | |
rotate <- function(spobj, angle=0) { | |
tmp <- spobj | |
suppressWarnings(proj4string(tmp) <- "+proj=aeqd +ellps=sphere +lat_0=90 +lon_0=0") | |
tmp <- spTransform(tmp, CRS(paste0("+proj=aeqd +ellps=sphere +lat_0=90 +lon_0=", -angle))) | |
return(tmp) | |
} | |
localize <- function(spobj){ | |
tmp <- spobj | |
tmp@coords[,1] <- tmp@coords[,1]-min(tmp@coords[,1]) | |
tmp@coords[,2] <- tmp@coords[,2]-min(tmp@coords[,2]) | |
return(tmp) | |
} | |
# Compute tests: | |
dt_prj_0 <- localize(rotate(data3D,0)) | |
dt_prj_45 <- localize(rotate(data3D,45)) | |
dt_prj_90 <- localize(rotate(data3D,90)) | |
dt_prj_135 <- localize(rotate(data3D,135)) | |
dt_prj_180 <- localize(rotate(data3D,180)) | |
# Display Results | |
grid.arrange( | |
ggplot(tidy(data3D),aes(x=x,y=y,colour=swe))+geom_point()+ggtitle("Original CRS")+coord_fixed(), | |
ggplot(tidy(dt_prj_0),aes(x=x,y=y,colour=swe))+geom_point()+ggtitle("Transform to Local CRS")+coord_fixed(), | |
ggplot(tidy(dt_prj_45),aes(x=x,y=y,colour=swe))+geom_point()+ggtitle("Transform 45deg Local CRS")+coord_fixed(), | |
ggplot(tidy(dt_prj_90),aes(x=x,y=y,colour=swe))+geom_point()+ggtitle("Transform 90deg Local CRS")+coord_fixed(), | |
ggplot(tidy(dt_prj_135),aes(x=x,y=y,colour=swe))+geom_point()+ggtitle("Transform 135deg Local CRS")+coord_fixed(), | |
ggplot(tidy(dt_prj_180),aes(x=x,y=y,colour=swe))+geom_point()+ggtitle("Transform 180deg Local CRS")+coord_fixed(), | |
ncol=3,top="Transformed Data Coordinates") | |
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Sample Output
Allows for arbitrary rotation & zeroing of coordinate reference system:
Hypothetically, If this was done before 3D kriging, could use this to output directly to grid cells for numerical simulation...