Generate Line Overlay

Calculates and returns an overlay of lines for the current height map.

generate_line_overlay(
  geometry,
  extent,
  heightmap = NULL,
  width = NA,
  height = NA,
  resolution_multiply = 1,
  color = "black",
  linewidth = 1,
  lty = 1,
  data_column_width = NULL,
  offset = c(0, 0)
)

Arguments

geometry

An sf object with LINESTRING geometry.

extent

Either an object representing the spatial extent of the scene (either from the raster, terra, sf, or sp packages), a length-4 numeric vector specifying c("xmin", "xmax","ymin","ymax"), or the spatial object (from the previously aforementioned packages) which will be automatically converted to an extent object.

heightmap

Default NULL. The original height map. Pass this in to extract the dimensions of the resulting overlay automatically.

width

Default NA. Width of the resulting overlay. Default the same dimensions as height map.

height

Default NA. Width of the resulting overlay. Default the same dimensions as height map.

resolution_multiply

Default 1. If passing in heightmap instead of width/height, amount to increase the resolution of the overlay, which should make lines/polygons/text finer. Should be combined with add_overlay(rescale_original = TRUE) to ensure those added details are captured in the final map.

color

Default black. Color of the lines.

linewidth

Default 1. Line width.

lty

Default 1. Line type. 1 is solid, 2 is dashed, 3 is dotted,4 is dot-dash, 5 is long dash, and 6 is dash-long-dash.

data_column_width

Default NULL. The numeric column to map the width to. The maximum width will be the value specified in linewidth.

offset

Default c(0,0). Horizontal and vertical offset to apply to the line, in units of geometry.

Value

Semi-transparent overlay with contours.

Examples

#Add the included `sf` object with roads to the montereybay dataset
if(run_documentation()) {
water_palette = colorRampPalette(c("darkblue", "dodgerblue", "lightblue"))(200)
bathy_hs = height_shade(montereybay, texture = water_palette)
montereybay %>% 
 height_shade() %>%
 add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0))  %>%
 add_overlay(generate_line_overlay(monterey_roads_sf, 
                                   attr(montereybay,"extent"), heightmap = montereybay))  %>%
 add_shadow(ray_shade(montereybay,zscale=50),0.3) %>%
 plot_map()
}

if(run_documentation()) {
#Change the line width, color, and transparency
montereybay %>%
 height_shade() %>%
 add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0))  %>%
 add_overlay(generate_line_overlay(monterey_roads_sf, linewidth=3, color="white",
                                   attr(montereybay,"extent"), heightmap = montereybay),
                                   alphalayer=0.8)  %>%
 add_shadow(ray_shade(montereybay,zscale=50),0.3) %>%
 plot_map()
}

if(run_documentation()) {
#Manually specify the width and height to improve visual quality of the lines
montereybay %>%
 height_shade() %>%
 add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0))  %>%
 add_shadow(ray_shade(montereybay,zscale=50),0.3) %>%
 add_overlay(generate_line_overlay(monterey_roads_sf, linewidth=3, color="white",
                                   attr(montereybay,"extent"), width = 1080, height = 1080),
                                   alphalayer=0.8)  %>%
 plot_map()
}