pliman (version 3.1.0)

shapefile_build: Build a shapefile from a mosaic raster

Description

This function takes a mosaic raster to create a shapefile containing polygons for the specified regions. Users can drawn Areas of Interest (AOIs) that can be either a polygon with n sides, or a grid, defined by nrow, and ncol arguments.

Usage

shapefile_build(
  mosaic,
  basemap = NULL,
  controlpoints = NULL,
  r = 3,
  g = 2,
  b = 1,
  crop_to_shape_ext = TRUE,
  grid = TRUE,
  nrow = 1,
  ncol = 1,
  nsides = 200,
  plot_width = NULL,
  plot_height = NULL,
  layout = "lrtb",
  serpentine = TRUE,
  build_shapefile = TRUE,
  check_shapefile = FALSE,
  sf_to_polygon = FALSE,
  buffer_edge = 1,
  buffer_col = 0,
  buffer_row = 0,
  as_sf = TRUE,
  verbose = TRUE,
  max_pixels = 1e+06,
  downsample = NULL,
  quantiles = c(0, 1)
)

Value

A list with the built shapefile. Each element is an sf object with the coordinates of the drawn polygons.

Arguments

mosaic

A SpatRaster object, typically imported using mosaic_input(). If not provided, a latitude/longitude basemap will be generated in the "EPSG:4326" coordinate reference system.

basemap

An optional mapview object.

controlpoints

An sf object created with mapedit::editMap(), containing the polygon that defines the region of interest to be analyzed.

r, g, b

The layer for the Red, Green and Blue band, respectively. Defaults to 1, 2, and 3.

crop_to_shape_ext

Crop the mosaic to the extension of shapefile? Defaults to TRUE. This allows for a faster index computation when the region of the built shapefile is much smaller than the entire mosaic extension.

grid

Logical, indicating whether to use a grid for segmentation (default: TRUE).

nrow

Number of rows for the grid (default: 1).

ncol

Number of columns for the grid (default: 1).

nsides

The number of sides if the geometry is generated with Draw Circle tool.

plot_width, plot_height

The width and height of the plot shape (in the mosaic unit). It is mutually exclusiv with buffer_col and buffer_row.

layout

Character: one of

• 'tblr' for top/bottom left/right orientation

• 'tbrl' for top/bottom right/left orientation

• 'btlr' for bottom/top left/right orientation

• 'btrl' for bottom/top right/left orientation

• 'lrtb' for left/right top/bottom orientation

• 'lrbt' for left/right bottom/top orientation

• 'rltb' for right/left top/bottom orientation

• 'rlbt' for right/left bottom/top orientation

serpentine

Create a serpentine-based layout? Defaults to FALSE.

build_shapefile

Logical, indicating whether to interactively draw ROIs if the shapefile is NULL (default: TRUE).

check_shapefile

Logical, indicating whether to validate the shapefile with an interactive map view (default: TRUE). This enables live editing of the drawn shapefile by deleting or changing the drawn grids.

sf_to_polygon

Convert sf geometry like POINTS and LINES to POLYGONS? Defaults to FALSE. Using TRUE allows using POINTS to extract values from a raster using exactextractr::exact_extract().

buffer_edge

Width of the buffer around the shapefile (default: 5).

buffer_col, buffer_row

Buffering factor for the columns and rows, respectively, of each individual plot's side. A value between 0 and 0.5 where 0 means no buffering and 0.5 means complete buffering (default: 0). A value of 0.25 will buffer the plot by 25% on each side.

as_sf

Logical value indicating whether to convert the imported shapefile to an sf object (default is TRUE).

verbose

Logical, indicating whether to display verbose output (default: TRUE).

max_pixels

Maximum number of pixels to render in the map or plot (default: 500000).

downsample

Downsampling factor to reduce the number of pixels (default: NULL). In this case, if the number of pixels in the image (width x height) is greater than max_pixels a downsampling factor will be automatically chosen so that the number of plotted pixels approximates the max_pixels.

quantiles

the upper and lower quantiles used for color stretching.

Details

Since multiple blocks can be created, the length of arguments grid, nrow, ncol, buffer_edge, buffer_col, and buffer_row can be either an scalar (the same argument applied to all the drawn blocks), or a vector with the same length as the number of drawn blocks. In the last, shapefiles in each block can be created with different dimensions.

Examples

if (interactive() && requireNamespace("EBImage")) {
library(pliman)
mosaic <- mosaic_input(system.file("ex/elev.tif", package="terra"))
shps <-
      shapefile_build(mosaic,
                      nrow = 6,
                      ncol = 3,
                      buffer_row = -0.05,
                      buffer_col = -0.25,
                      check_shapefile = FALSE,
                      build_shapefile = FALSE) ## Use TRUE to interactively build the plots
mosaic_plot(mosaic)
shapefile_plot(shps[[1]], add = TRUE)
}