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Create a basemap with customised bounding box using map tiles

Source: R/fun_create_bm_tiles.R
atl_create_bm_tiles.Rd

This function creates a basemap using spatial data layers, allowing for custom bounding boxes, aspect ratios, and scale bar adjustments.

Usage

atl_create_bm_tiles(
  data = NULL,
  x = "x",
  y = "y",
  buffer = 100,
  asp = "16:9",
  option = "Esri.WorldImagery",
  zoom = 15,
  scalebar = TRUE,
  sc_location = "br",
  sc_cex = 1,
  sc_height = 0.3,
  sc_pad_x = 0.4,
  sc_pad_y = 0.6,
  projection = sf::st_crs(32631)
)

Arguments

data

A data.table or an object convertible to data.table containing spatial points or a sf bounding box. Defaults to a single point around Griend if NULL.

x

A character string specifying the column with x-coordinates. Defaults to "x".

y

A character string specifying the column with y-coordinates. Defaults to "y".

buffer

A numeric value (in meters) specifying the buffer distance for the bounding box. Default is 1000.

asp

A character string specifying the desired aspect ratio in the format "width:height". Default is "16:9", if NULL returns simple bounding box without modifying aspect ratio.

option

A character string specifying the map tile provider. Options include "Esri.WorldImagery", ""OpenStreetMap", "Esri", "CARTO", and "Thunderforest". See supported by the maptiles package, see:

zoom

Numeric value specifying the zoom level for the map tiles. Zoom levels are described in the OpenStreetMap wiki: https://wiki.openstreetmap.org/wiki/Zoom_levels.

scalebar

TRUE or FALSE for adding a scalebar to the plot.

sc_location

A character string specifying the location of the scale bar. Default is "br" (bottom right).

sc_cex

Numeric value for the scale bar text size. Default is 0.7.

sc_height

A unit object specifying the height of the scale bar. Default is unit(0.25, "cm").

sc_pad_x

A unit object specifying horizontal padding for the scale bar. Default is unit(0.25, "cm").

sc_pad_y

A unit object specifying vertical padding for the scale bar. Default is unit(0.5, "cm").

projection

The coordinate reference system (CRS) for the spatial data. Defaults to EPSG:32631 (WGS 84 / UTM zone 31N). Output is always EPSG:4326. Bounding box calculation is much faster when uusing EPSG:3263, so use it like this whenwever possible and then only plot the movement tracks in EPSG:4326 on the map.

Value

A ggplot2 object representing the base map with the specified settings.

Author

Johannes Krietsch

Examples

# packages
library(tools4watlas)
library(ggplot2)

# example with open street map
bm <- atl_create_bm_tiles(
  buffer = 15000, option = "OpenStreetMap", zoom = 12
)
print(bm)


# example with satellite map
bm <- atl_create_bm_tiles(
  buffer = 15000, option = "Esri.WorldImagery", zoom = 12
)
print(bm)


# example with bbox from data and movement data
data <- data_example

# add transformed coordinates in projection of the base map (EPSG:4326)
data <- atl_transform_dt(data)

# plot points and tracks using transformed coordinates.
bm +
  geom_path(
    data = data, aes(x_4326, y_4326, colour = tag),
    linewidth = 0.5, alpha = 0.1, show.legend = FALSE
  ) +
  geom_point(
    data = data, aes(x_4326, y_4326, colour = tag),
    size = 0.5, alpha = 1, show.legend = FALSE
  ) +
  scale_color_discrete(name = paste("N = ", length(unique(data$tag)))) +
  theme(legend.position = "top")