composite_ppi {bioRad} | R Documentation |

`ppi`

)Combines multiple plan position indicators (`ppi`

) into a single
`ppi`

. Can be used to make a composite of `ppi`

's from multiple
radars.

composite_ppi( x, param = "DBZH", nx = 100, ny = 100, xlim, ylim, res, crs, raster = NA, method = "max", idp = 2, idw_max_distance = NA )

`x` |
A list of |

`param` |
Scan parameter to composite. |

`nx` |
number of raster pixels in the x (longitude) dimension |

`ny` |
number of raster pixels in the y (latitude) dimension |

`xlim` |
x (longitude) range |

`ylim` |
y (latitude) range |

`res` |
numeric vector of length 1 or 2 to set the resolution of the raster (see res).
If this argument is used, arguments |

`crs` |
character or object of class CRS. PROJ.4 type description of a Coordinate Reference System (map projection). When 'NA' (default), an azimuthal equidistant projection with origin at the radar location is used. To use a WSG84 (lat,lon) projection, use crs="+proj=longlat +datum=WGS84" |

`raster` |
(optional) RasterLayer with a CRS. When specified this raster topology is used for the output, and nx, ny, res arguments are ignored. |

`method` |
string. Compositing method, one of "mean", "min", "max" or "idw" |

`idp` |
numeric. inverse distance weighting power |

`idw_max_distance` |
numeric. Maximum distance from the radar to consider in inverse distance weighting. Measuruments beyond this distance will have a weighting factor of zero. |

This function composites multiple ppi objects into a ppi object that combines all data.

Either multiple ppi's of different scan elevation of the same radar may be combined, or ppi's of different radars can be composited.

Argument `method`

determines how values of different ppi's at the same
geographic location are combined.

`"mean"`

Compute the average value

`"max"`

Compute the maximum value. If ppi's are of the same radar and the same polar volume, this computes a max product, showing the maximum detected signal at that geographic location.

`"min"`

Compute the minimum value

`"idw"`

This option is useful primarily when compositing ppi's of multiple radars. Performs an inverse distance weighting, where values are weighted according to 1/(distance from the radar)^

`idp`

The coordinates system of the returned `ppi`

is a WGS84
(lat,lon) datum.

This function is a prototype and under active development

A `ppi`

.

# locate example volume file: pvolfile <- system.file("extdata", "volume.h5", package = "bioRad") # load the file: example_pvol <- read_pvolfile(pvolfile) # calculate a ppi for each elevation scan my_ppis <- lapply(example_pvol$scans, project_as_ppi) # overlay the ppi's, calculating the maximum value observed # across the available scans at each geographic location my_composite <- composite_ppi(my_ppis, method="max") ## Not run: # download basemap bm <- download_basemap(my_composite) # plot the calculated max product on the basemap map(my_composite, bm) ## End(Not run)

[Package *bioRad* version 0.5.2 Index]