locaR (version 0.1.2)

makeSearchMap: Create a grid over which to search for sound sources.

Description

makeSearchMap creates the three-dimensional array over which to search for sound sources.

Usage

makeSearchMap(
  easting,
  northing,
  elevation,
  margin = 10,
  zMin = -1,
  zMax = 10,
  resolution = 1
)

Value

A list defining the search map.

Arguments

easting

vector of x coordinates of microphones.

northing

vector of y coordinates of microphones.

elevation

vector of z coordinates of microphones.

margin

distance (in meters) to extend the search grid beyond the x-y limits of the microphone locations. The same buffer is applied to x and y coordinates.

zMin

distance (in meters) to begin search relative to the microphone with the lowest elevation. Typically a small negative number to ensure that the grid search begins slightly below the lowest microphone.

zMax

distance (in meters) to end search relative to the microphone with the highest elevation. Typically a positive number to ensure that the grid search ends well above the highest microphone.

resolution

resolution of the search map, in meters.

Details

The localization algorithms used in this package can search for sound sources over areas with arbitrary size and with arbitrary resolution. However, speed can sometimes be slow. Generally speaking, the speed of localization calculations correlates directly with the number of grid cells to be searched. Speed can therefore be increased by searching a smaller area (i.e. by reducing the margin, increasing zMin, or decreasing zMax), or by searching with a coarser grain (i.e. by increasing the resolution).

The final list defining the search map includes three arrays containing x, y and z coordinates of each grid cell, as well as the resolution and range of values in the x, y and z directions. This list is passed to other functions for localization.

Examples

    #read coordinates.
    coords <- read.csv(system.file('extdata', 'Vignette_Coordinates.csv', package = 'locaR'),
       stringsAsFactors = FALSE)
    #make search map.
    sm <- makeSearchMap(easting = coords$Easting,
                       northing = coords$Northing,
                       elevation = coords$Elevation)