Convert between pixel and georeferenced coordinates

pixel_to_xy() takes pixel and line positions to georeferenced ones, and xy_to_pixel() takes them back again.

Usage

pixel_to_xy(geotransform, pixel, line)

xy_to_pixel(geotransform, x, y)

Arguments

geotransform

A numeric vector of length 6, as a dataset's geotransform property returns.

pixel, line

Numeric vectors of the same length. Fractional positions are meaningful: whole numbers fall on pixel corners, so the centre of the first pixel is pixel = 0.5, line = 0.5.

x, y

Numeric vectors of the same length, in the dataset's coordinate reference system.

Value

pixel_to_xy() a list of x and y. xy_to_pixel() a list of pixel and line.

Details

Both are vectorised, so a whole set of positions is one call.

Examples

ds <- gdal_open(system.file("extdata/test.tif", package = "GDAL7"))
gt <- ds@geotransform

# The centre of the first pixel, and back again.
pixel_to_xy(gt, 0.5, 0.5)
#> $x
#> [1] -171
#> 
#> $y
#> [1] 81
#> 
xy_to_pixel(gt, -180 + 9, 90 - 9)
#> $pixel
#> [1] 0.5
#> 
#> $line
#> [1] 0.5
#> 

gdal_close(ds)