Add stars/raster image to a leaflet map using optimised rendering.

Usage

addGeoRaster(
  map,
  x,
  group = NULL,
  layerId = NULL,
  resolution = 96,
  opacity = 0.8,
  options = leaflet::tileOptions(),
  colorOptions = NULL,
  project = TRUE,
  pixelValuesToColorFn = NULL,
  autozoom = TRUE,
  ...
)

Arguments

map: the map to add the raster data to.
x: the stars/raster object to be rendered.
group: the name of the group this raster image should belong to.
layerId: the layerId.
resolution: the target resolution for the simple nearest neighbor interpolation. Larger values will result in more detailed rendering, but may impact performance. Default is 96 (pixels).
opacity: opacity of the rendered layer.
options: options to be passed to the layer. See tileOptions for details.
colorOptions: list defining the palette, breaks and na.color to be used.
project: whether to project the RasterLayer to conform with leaflets expected crs. Defaults to TRUE and things are likely to go haywire if set to FALSE.
pixelValuesToColorFn: optional JS function to be passed to the browser. Can be used to fine tune and manipulate the color mapping. See https://github.com/r-spatial/leafem/issues/25 for some examples.
autozoom: whether to automatically zoom to the full extent of the layer. Default is TRUE
...: currently not used.

Value

A leaflet map object.

Details

This uses the leaflet plugin 'georaster-layer-for-leaflet' to render raster data. See https://github.com/GeoTIFF/georaster-layer-for-leaflet for details. The clue is that rendering uses simple nearest neighbor interpolation on-the-fly to ensure smooth rendering. This enables handling of larger rasters than with the standard addRasterImage.

Examples

if (interactive()) {
  library(leaflet)
  library(leafem)
  library(stars)

  tif = system.file("tif/L7_ETMs.tif", package = "stars")
  x1 = read_stars(tif)
  x1 = x1[, , , 3] # band 3

  leaflet() %>%
    addTiles() %>%
    leafem:::addGeoRaster(
      x1
      , opacity = 1
      , colorOptions = colorOptions(
        palette = grey.colors(256)
      )
    )
}