merge_spatial {lidR}

Merge a point cloud with a source of spatial data

Description

Merge a point cloud with a source of spatial data. It adds an attribute along each point based on a value found in the spatial data. Sources of spatial data can be a ⁠SpatialPolygons*⁠, an sf/sfc, a ⁠Raster*⁠, a stars, or a SpatRaster.

• ⁠SpatialPolygons*⁠, sf and sfc: it checks if the points belongs within each polygon. If the parameter attribute is the name of an attribute in the table of attributes it assigns to the points the values of that attribute. Otherwise it classifies the points as boolean. TRUE if the points are in a polygon, FALSE otherwise.

• RasterLayer, single band stars or single layer SpatRaster: it attributes to each point the value found in each pixel of the raster.

• RasterStack, RasterBrick, multibands stars or multilayer SpatRaster must have 3 layers for RGB colors. It colorizes the point cloud with RGB values.

Usage

merge_spatial(las, source, attribute = NULL)

Arguments

las

An object of class LAS

source

An object of class ⁠SpatialPolygons*⁠ or sf or sfc or RasterLayer or RasterStack or RasterBrick or stars.

attribute

character. The name of an attribute in the table of attributes or the name of a new column in the LAS object. Not relevant for RGB colorization.

Value

a LAS object

Examples

LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
shp     <- system.file("extdata", "lake_polygons_UTM17.shp", package = "lidR")

las   <- readLAS(LASfile, filter = "-keep_random_fraction 0.1")
lakes <- sf::st_read(shp, quiet = TRUE)

# The attribute "inlake" does not exist in the shapefile.
# Points are classified as TRUE if in a polygon
las    <- merge_spatial(las, lakes, "inlakes")     # New attribute 'inlakes' is added.
names(las)

forest <- filter_poi(las, inlakes == FALSE)
#plot(forest)

# The attribute "LAKENAME_1" exists in the shapefile.
# Points are classified with the values of the polygons
las <- merge_spatial(las, lakes, "LAKENAME_1")     # New column 'LAKENAME_1' is added.
names(las)