plot a raster file or vrt_x object — plot.Rcpp

A wrapper around gdalraster::plot_raster that simplifies the process of plotting a raster file.

Usage

# S3 method for class 'Rcpp_GDALRaster'
plot(
  x,
  bands = 1,
  xsize = NULL,
  ysize = NULL,
  max_pixels = 2.5e+07,
  scale_values = TRUE,
  col_tbl = NULL,
  maxColorValue = 1,
  normalize = TRUE,
  minmax_def = NULL,
  minmax_pct_cut = NULL,
  col = NULL,
  pixel_fn = NULL,
  xlim = NULL,
  ylim = NULL,
  interpolate = TRUE,
  axes = TRUE,
  main = "",
  xlab = "x",
  ylab = "y",
  legend = FALSE,
  digits = NULL,
  na_col = grDevices::rgb(0, 0, 0, 0),
  mar = c(0, 0, 0, 0),
  ...
)

plot_raster_src(
  x,
  bands = 1,
  col = grDevices::hcl.colors(10, "Viridis"),
  title = c("description", "dttm", "none"),
  rgb_trans = c("linear", "gamma", "hist", "hist_all"),
  col_tbl = NULL,
  minmax_def = NULL,
  minmax_pct_cut = NULL,
  xlim = NULL,
  ylim = NULL,
  interpolate = TRUE,
  axes = TRUE,
  main = "",
  xlab = "",
  ylab = "",
  legend = if (length(bands) == 1) TRUE else FALSE,
  digits = NULL,
  na_col = "#95acbe",
  ...
)

# S3 method for class 'vrt_block'
plot(x, ..., config_options = gdal_config_opts())

# S3 method for class 'vrt_stack'
plot(x, ..., config_options = gdal_config_opts())

# S3 method for class 'vrt_stack_warped'
plot(x, ..., config_options = gdal_config_opts())

# S3 method for class 'vrt_collection'
plot(x, item, ..., config_options = gdal_config_opts())

Arguments

x: A path to a raster file
bands: a numeric vector of band numbers to plot must be of length 1 or 3.
xsize: Integer. Desired width of the plotted raster in pixels. If NULL (default), dimension is rescaled in line with the device size.
ysize: Integer. Desired height of the plotted raster in pixels. If NULL (default), dimension is rescaled in line with the device size.
max_pixels: Numeric. Maximum number of pixels to read. If xsize * ysize exceeds this value, the raster will be downsampled.
scale_values: Logical. Whether to apply scale and offset values from the raster metadata.
col_tbl: A data frame with the columns: "VALUE", "RED", "GREEN", "BLUE".
maxColorValue: Numeric. Maximum color value when using a color table.
normalize: Logical. Whether to normalize pixel values to [0,1] range before color mapping. Automatically disabled for discrete data.
minmax_def: Numeric vector of min/max values for color scaling. For RGB plots, should be length 6: c(min_r, min_g, min_b, max_r, max_g, max_b).
minmax_pct_cut: Numeric vector of length 2. Percentile cutoff values for color scaling (e.g., c(2, 98) for 2nd and 98th percentiles).
col: a character vector of colors to use when plotting a single band. for example when sea presents as very dark.
pixel_fn: Function to apply to pixel values before plotting.
xlim: Numeric vector of length 2. X-axis limits in coordinate system units.
ylim: Numeric vector of length 2. Y-axis limits in coordinate system units.
interpolate: Logical. Whether to apply smoothing to the raster image.
axes: Logical. Whether to draw axes and axis labels.
main: Character string. Plot title.
xlab: Character string. X-axis label.
ylab: Character string. Y-axis label.
legend: Logical. Whether to draw a color legend. Only supported for single-band plots. Automatically detects discrete vs continuous data.
digits: Integer. Number of decimal places for legend labels. If NULL (default), automatically determines appropriate precision based on data range.
na_col: Color for NA/nodata pixels. Default is transparent.
mar: Numeric vector of length 4. Additional margin adjustments to add to the base margins when legend is enabled.
...: Additional arguments passed to plot.window.
title: a character string indicating what to use as the title of the plot. One of "description", "dttm", or "none". If "description" the band description (name) is used, if "dttm" the datetime of the block is used, if "none" no title is used. Ignored if main is provided.
rgb_trans: a character string indicating the type of RGB transformation to apply when plotting 3 bands. One of "linear", "gamma", "hist", or "hist_all". See details for more information.
config_options: A named character vector of gdal config options to set before attempting to read the VRT.
item: The numeric index of the item, in the vrt_collection, to plot

Details

When plotting 3 bands, the rgb_trans parameter controls the type of transformation applied to the RGB values before plotting. The options are:

"linear": No transformation is applied (default).
"gamma": A gamma correction is applied to enhance mid-tone contrast.
"hist": Histogram equalization is applied to each band individually to enhance contrast.
"hist_all": Histogram equalization is applied across all bands to enhance overall contrast.

Examples

s2_imgs <- fs::dir_ls(system.file("s2-data", package = "vrtility"))
ds <- methods::new(gdalraster::GDALRaster, s2_imgs[2])

plot(
  ds,
  bands = 4,
  legend = TRUE
)


ds$close()
s2_imgs <- fs::dir_ls(system.file("s2-data", package = "vrtility"))
plot_raster_src(
  s2_imgs[3],
  bands = c(3, 2, 1),
)