affinething {affinity}

Use affine logic interactively georegister a raster

Description

User clicks are collected in a controlled way for use by domath().

Usage

affinething(x, rgb = FALSE)

Arguments

x

a raster

rgb

use RGB plot for a raster with 3 layers

Details

Obtain control points for the simple affine transform (offset and scale) on an ungeoreferenced image.

Value

matrix of x,y coordinates in the space of the current raster extent

Examples

## Not run: 
library(raster)
r <- raster("my_unreferenced_raster.png")
xy <- affinething(r)  ## click on two points that you know a location of
my_x <- c(1000, 2000)
my_y <- c(-1000, -500)
prj <- "+proj=laea +lon=147 +lat_0=-42" ## use your own map projection, that correspond to my_x/my_y
pt <- cbind(my_x, my_y)
## now convert those control points to an extent for your raster
ex <- domath(pt, xy, r, prj)

## now we can fix up the data
r <- raster::setExtent(r, ex)
raster::projection(r) <- prj
## hooray!

## End(Not run)