Pre-build the routing graph from a cost surface so that multiple
route_corridor calls can skip graph construction.
The returned object is a snapshot of the cost surface at build time;
subsequent edits to the raster do not affect the graph.
Arguments
- cost_surface
A terra SpatRaster (single band). Same requirements as
route_corridor.- neighbours
Integer. Cell connectivity: 4, 8 (default), or 16. Fixed at build time.
- resolution_factor
Integer, default 1L. If > 1, the surface is aggregated before graph construction. Fixed at build time.
Value
An opaque spopt_corridor_graph object for use with
route_corridor.
Details
The object retains both the CSR graph (in Rust) and an independent copy
of the raster (for coordinate mapping). The printed graph_storage
reflects only the CSR arrays, not the raster copy.
Examples
# \donttest{
library(terra)
#> terra 1.9.11
r <- rast(nrows = 500, ncols = 500, xmin = 0, xmax = 500000,
ymin = 0, ymax = 500000, crs = "EPSG:32614")
values(r) <- runif(ncell(r), 0.5, 2.0)
g <- corridor_graph(r, neighbours = 8L)
print(g)
#> Corridor graph
#> Grid: 500 x 500 (250,000 cells)
#> Cell size: 1000.0 x 1000.0
#> Neighbours: 8 (1,994,004 edges)
#> Build time: 0.008s | Graph storage: ~33.9 MB
path <- route_corridor(g, c(50000, 50000), c(450000, 450000))
# }