R: Map the pulse or point density

grid_density {lidR} | R Documentation

## Map the pulse or point density

### Description

Creates a map of the point density. If a "pulseID" attribute is found, also returns a map of the pulse density.

### Usage

    grid_density(las, res = 4)

### Arguments

`las` | An object of class LAS or LAScatalog.
`res` | numeric. The size of a grid cell in LiDAR data coordinates units. Default is 4 = 16 square meters.

### Value

A `RasterLayer` or a `RasterBrick` containing a numeric value in each cell. If the `RasterLayer`s are written on disk when running the function with a `LAScatalog`, a virtual raster mosaic is returned (see gdalbuildvrt)

### Working with a `LAScatalog`

This section appears in each function that supports a LAScatalog as input.

In `lidR` when the input of a function is a LAScatalog the function uses the LAScatalog processing engine. The user can modify the engine options using the available options. A careful reading of the engine documentation is recommended before processing `LAScatalogs`. Each `lidR` function should come with a section that documents the supported engine options.

The `LAScatalog` engine supports `.lax` files that significantly improve the computation speed of spatial queries using a spatial index. Users should really take advantage a `.lax` files, but this is not mandatory.

### Supported processing options

Supported processing options for a `LAScatalog` in `grid_*` functions (in bold). For more details see the LAScatalog engine documentation:

- chunk size: How much data is loaded at once. The chunk size may be slightly modified internally to ensure a strict continuous wall-to-wall output even when chunk size is equal to 0 (processing by file).

- chunk buffer: This function guarantees a strict continuous wall-to-wall output. The `buffer` option is not considered.

- chunk alignment: Align the processed chunks. The alignment may be slightly modified internally to ensure a strict continuous wall-to-wall output.

- progress: Displays a progress estimate.

- output files: Return the output in R or write each cluster's output in a file. Supported templates are `{XLEFT}`, `{XRIGHT}`, `{YBOTTOM}`, `{YTOP}`, `{XCENTER}`, `{YCENTER}` `{ID}` and, if chunk size is equal to 0 (processing by file), `{ORIGINALFILENAME}`.

- select: The `grid_*` functions usually 'know' what should be loaded and this option is not considered. In grid_metrics this option is respected.

- filter: Read only the points of interest.

### Examples

    LASfile <- system.file("extdata", "Megaplot.laz", package="lidR")
    las <- readLAS(LASfile,  filter = "-inside 684800 5017800 684900 5017900")

    d <- grid_density(las, 5)
    plot(d)

    las <- retrieve_pulses(las)
    d <- grid_density(las)
    plot(d)

[Package lidR version 3.2.2 Index]