bhuvan_raster: Download Bhuvan NTL raster tiles for a region

In lightson: Download and Analyse Nighttime Lights Satellite Data

Download Bhuvan NTL raster tiles for a region

Description

Fetches annual nighttime lights GeoTIFF tiles from the Bhuvan WMS service for a given spatial extent and converts the classed RGB map to a single-band radiance raster.

Usage

bhuvan_raster(
  region,
  years,
  force = FALSE,
  width = 1024,
  height = 1024,
  bbox_pad = c(0, 0, 0, 0)
)

Arguments

region	An sf object, SpatVector, or ISO 3166-1 alpha-3 country code (e.g., "IND"). Used to derive the WMS bounding box.
years	Integer vector of years to download (2012-2024).
force	Logical. If TRUE, re-download even if cached. Default FALSE.
width, height	Pixel dimensions of the WMS request. Default 1024x1024.
bbox_pad	Numeric vector of length 1 or 4 (xmin, ymin, xmax, ymax sides) in degrees, added to the region bounding box before the WMS request. Useful when GADM boundaries clip disputed territories (e.g. bbox_pad = c(0, 0, 0, 3.5) extends the north edge by 3.5 degrees to include all of Jammu and Kashmir).

Details

The Bhuvan WMS does not serve continuous radiance. It returns a map with four colour classes, which are converted to representative radiance values in nW/cm^2/sr:

Colour	Class	Value
black	< 5	2.5
blue-grey	5 - 25	15
cream	26 - 200	112.5
red	> 200	200

The first three values are class midpoints; the open-ended top class is set to its floor, so the brightest areas are underestimated. Pixels that match no class (the portal's watermark and its anti-aliased edges) are NA. Treat the output as coarse, banded radiance: use VIIRS from ntl_download() when you need continuous calibrated values.

Value

A named list of single-band SpatRaster objects, keyed by year (e.g., list("2020" = rast(...), "2021" = rast(...))). Errors if the WMS fetch fails for any requested year.

Collection break

Bhuvan NTL data from 2024 onwards is derived from VNP46A4 Collection 2.0, while 2012-2023 uses the legacy Collection 1.0. The two collections use different calibration and atmospheric correction algorithms, so values are not directly comparable across this boundary.

Examples

states <- get_india_admin("state")
rasters <- bhuvan_raster(states, years = 2021:2022)
panel <- extract_panel(rasters, states, id_col = "state_name")

lightson documentation built on Nov. 3, 2026, 5:07 p.m.