rayshader: generate_label_overlay – R documentation

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generate_label_overlay

Generate Label Overlay

Description

This uses the 'maptools::placeLabel()' function to generate labels for the given scene. Either use an 'sf' object or manually specify the x/y coordinates and label.

Usage

generate_label_overlay(
  labels,
  extent,
  x = NULL,
  y = NULL,
  heightmap = NULL,
  width = NA,
  height = NA,
  text_size = 1,
  color = "black",
  font = 1,
  pch = 16,
  point_size = 1,
  point_color = NA,
  offset = c(0, 0),
  data_label_column = NULL,
  halo_color = NA,
  halo_expand = 0,
  halo_alpha = 1,
  halo_offset = c(0, 0),
  halo_blur = 1,
  seed = NA
)

Arguments

`labels`	A character vector of labels, or an 'sf' object with 'POINT' geometry and a column for labels.
`extent`	A 'raster::Extent' object with the bounding box for the height map used to generate the original map.
`x`	Default 'NULL'. The x-coordinate, if 'labels' is not an 'sf' object.
`y`	Default 'NULL'. The y-coordinate, if 'labels' is not an 'sf' 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.
`text_size`	Default '1'. Text size.
`color`	Default 'black'. Color of the labels.
`font`	Default '1'. An integer which specifies which font to use for text. If possible, device drivers arrange so that 1 corresponds to plain text (the default), 2 to bold face, 3 to italic and 4 to bold italic.
`pch`	Default '20', solid. Point symbol. '0' = square, '1' = circle, '2' = triangle point up, '3' = plus, '4' = cross, '5' = diamond, '6' = triangle point down, '7' = square cross, '8' = star, '9' = diamond plus, '10' = circle plus, '11' = triangles up and down, '12' = square plus, '13' = circle cross, '14' = square and triangle down, '15' = filled square, '16' = filled circle, '17' = filled triangle point-up, '18' = filled diamond, '19' = solid circle, '20' = bullet (smaller circle), '21' = filled circle blue, '22' = filled square blue, '23' = filled diamond blue, '24' = filled triangle point-up blue, '25' = filled triangle point down blue
`point_size`	Default '0', no points. Point size.
`point_color`	Default 'NA'. Colors of the points. Unless otherwise specified, this defaults to 'color'.
`offset`	Default 'c(0,0)'. Horizontal and vertical offset to apply to the label, in units of 'geometry'.
`data_label_column`	Default 'NULL'. The column in the 'sf' object that contains the labels.
`halo_color`	Default 'NA', no halo. If a color is specified, the text label will be surrounded by a halo of this color.
`halo_expand`	Default '2'. Number of pixels to expand the halo.
`halo_alpha`	Default '1'. Transparency of the halo.
`halo_offset`	Default 'c(0,0)'. Horizontal and vertical offset to apply to the halo, in units of 'geometry'.
`halo_blur`	Default ‘1'. Amount of blur to apply to the halo. Values greater than '30' won’t result in further blurring.
`seed`	Default 'NA', no seed. Random seed for ensuring the consistent placement of labels around points.

Value

Semi-transparent overlay with labels.

Examples

#Add the included `sf` object with roads to the montereybay dataset
#Only run these examples if the `magick` package is installed.
if ("magick" %in% rownames(utils::installed.packages())) {

#Create the water palette
water_palette = colorRampPalette(c("darkblue", "dodgerblue", "lightblue"))(200)
bathy_hs = height_shade(montereybay, texture = water_palette)

#We're plotting the polygon data here for counties around Monterey Bay. We'll first
#plot the county names at the polygon centroids.
bathy_hs %>% 
 add_shadow(lamb_shade(montereybay,zscale=50),0.3) %>%
 add_overlay(generate_polygon_overlay(monterey_counties_sf, palette = rainbow, 
                                      extent = attr(montereybay,"extent"),
                                      heightmap = montereybay)) %>% 
 add_overlay(generate_label_overlay(labels=monterey_counties_sf,
                                    color="black", point_size = 1, text_size = 1,
                                    data_label_column = "NAME",
                                    extent= attr(montereybay,"extent"), heightmap = montereybay,
                                    seed=1))  %>%
 plot_map()

#It's hard to read these values, so we'll add a white halo.
bathy_hs %>% 
 add_shadow(lamb_shade(montereybay,zscale=50),0.3) %>%
 add_overlay(generate_polygon_overlay(monterey_counties_sf, palette = rainbow, 
                                      extent = attr(montereybay,"extent"),
                                      heightmap = montereybay)) %>% 
 add_overlay(generate_label_overlay(labels=monterey_counties_sf,
                                    color="black", point_size = 1, text_size = 1,
                                    data_label_column = "NAME",
                                    extent= attr(montereybay,"extent"), heightmap = montereybay,
                                    halo_color = "white", halo_expand = 3,
                                    seed=1))  %>%
 plot_map()


#Plot the actual town locations, using the manual plotting interface instead of the `sf` object
montereybay %>%
 height_shade() %>%
 add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0)) %>% 
 add_shadow(lamb_shade(montereybay,zscale=50),0.3) %>%
 add_overlay(generate_label_overlay(labels=as.character(monterey_counties_sf$NAME),
                                    x=as.numeric(as.character(monterey_counties_sf$INTPTLON)),
                                    y=as.numeric(as.character(monterey_counties_sf$INTPTLAT)),
                                    color="black", point_size = 1, text_size = 1,
                                    extent= attr(montereybay,"extent"), heightmap = montereybay,
                                    halo_color = "white", halo_expand = 3,
                                    seed=1))  %>%
 plot_map()

#Adding a softer blurred halo
montereybay %>%
 height_shade() %>%
 add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0)) %>% 
 add_shadow(lamb_shade(montereybay,zscale=50),0.3) %>%
 add_overlay(generate_label_overlay(labels=as.character(monterey_counties_sf$NAME),
                                    x=as.numeric(as.character(monterey_counties_sf$INTPTLON)),
                                    y=as.numeric(as.character(monterey_counties_sf$INTPTLAT)),
                                    color="black", point_size = 1, text_size = 1,
                                    extent= attr(montereybay,"extent"), heightmap = montereybay,
                                    halo_color = "white", halo_expand = 3, halo_blur=10,
                                    seed=1))  %>%
 plot_map()
 
#Changing the seed changes the locations of the labels
montereybay %>%
 height_shade() %>%
 add_overlay(generate_altitude_overlay(bathy_hs, montereybay, 0, 0)) %>% 
 add_shadow(lamb_shade(montereybay,zscale=50),0.3) %>%
 add_overlay(generate_label_overlay(labels=as.character(monterey_counties_sf$NAME),
                                    x=as.numeric(as.character(monterey_counties_sf$INTPTLON)),
                                    y=as.numeric(as.character(monterey_counties_sf$INTPTLAT)),
                                    color="black", point_size = 1, text_size = 1,
                                    extent= attr(montereybay,"extent"), heightmap = montereybay,
                                    halo_color = "white", halo_expand = 3, halo_blur=10,
                                    seed=2))  %>%
 plot_map()

}

rayshader

Create Maps and Visualize Data in 2D and 3D

v0.24.10

GPL-3

Authors

Tyler Morgan-Wall

Initial release

2021-04-25