Value of a COG at a point, via titiler

Asks the tile server what the layer shows at a coordinate, instead of the app opening a raster itself. The pixels the user is looking at and the number in the popup then come from the SAME source, so they cannot disagree – and the app needs no local copy of the surface, which is the point of publishing COGs.

Usage

cog_point_value(cog_url, lon, lat, base = atlas_bases()$titiler, timeout = 8)

Arguments

cog_url

the COG the layer is drawn from

lon, lat

coordinates in degrees (-180..180)

base

titiler base URL

timeout

seconds before giving up

Value

numeric value, or NA if the point is nodata/outside or the request fails – a popup is not worth an error dialog