reproj_extent: Reproject extent

In mdsumner/reproj: Coordinate System Transformations for Generic Map Data

Reproject extent

Description

A four figure extent (xmin, xmax, ymin, ymax) is used to approximate the boundary of its reprojected version by interpolating new vertices along each edge.

Usage

reproj_extent(extent, target, limit = NULL, ..., source = NULL)

Arguments

extent	a four element vector of extent c(xmin, xmax, ymin, ymax)
target	target specification (PROJ.4 string or epsg code)
limit	if used, a one or two element numeric vector to give the maximum radius to the edge of the extent from the middle
...	arguments passed to proj4::ptransform()
source	source specification (PROJ.4 string or epsg code)

Details

This is a simple version of what GDAL's 'SuggestedWarpOutput' does, and similar functions like the raster package 'projectExtent()'.

Internal functions unpack the various stages, and might be exposed in future. These stages are

1. interpolate around the boundary with correct ordering (can be used as a polygon or line)

2. reproject the interpolated boundary

3. summarize the interpolated boundary to the new extent

Value

four value extent c(xmin, xmax, ymin, ymax)

Examples

reproj_extent(c(0, 10, 0, 20), "+proj=laea", source = "+proj=longlat")

mdsumner/reproj documentation built on June 13, 2024, 9:28 p.m.