Take a linestring and add a third (z) dimension to its coordinates

elevation_add(
  routes,
  dem = NULL,
  method = "bilinear",
  terra = has_terra() && methods::is(dem, "SpatRaster")
)

Arguments

routes	Routes, the gradients of which are to be calculated. The object must be of class `sf` or `sfc` with `LINESTRING` geometries.
dem	Raster overlapping with `routes` and values representing elevations
method	The method of estimating elevation at points, passed to the `extract` function for extracting values from raster datasets. Default: `"bilinear"`.
terra	Should the `terra` package be used? `TRUE` by default if the package is installed and if `dem` is of class `SpatRast`

Value

An sf object that is identical to the input routes, except that the coordinate values in the ouput has a third z dimension representing the elevation of each vertex that defines a linear feature such as a road.

Examples

library(sf)
routes = lisbon_road_network[204, ]
dem = dem_lisbon_raster
(r3d = elevation_add(routes, dem))
#> Simple feature collection with 1 feature and 7 fields
#> Geometry type: LINESTRING
#> Dimension:     XYZ
#> Bounding box:  xmin: -87080.48 ymin: -105629.6 xmax: -87056.99 ymax: -105506.3
#> z_range:       zmin: 86.49414 zmax: 92.31126
#> Projected CRS: ETRS89 / Portugal TM06
#> # A tibble: 1 × 8
#>   OBJECTID Z_Min Z_Max Z_Mean Min_Slope Max_Slope Avg_Slope
#> *    <int> <dbl> <dbl>  <dbl>     <dbl>     <dbl>     <dbl>
#> 1     2997  86.5  92.3   89.9     0.334      32.0      7.49
#> # … with 1 more variable: geom <LINESTRING [m]>
library(sf)
st_z_range(routes)
#> NULL
st_z_range(r3d)
#>     zmin     zmax 
#> 86.49414 92.31126 
plot(st_coordinates(r3d)[, 3])
plot_slope(r3d)
# \donttest{
# Get elevation data (requires internet connection and API key):
r3d_get = elevation_add(cyclestreets_route)
#> Loading required namespace: ceramic
#> Preparing to download: 6 tiles at zoom = 14 from 
#> https://api.mapbox.com/v4/mapbox.terrain-rgb/
#> Error in curl::curl_download(url = api_query, outfile): HTTP error 401.
plot_slope(r3d_get)
#> Error in st_crs(x): object 'r3d_get' not found
# }