R/Class-Viewshed.R

In land-info-lab/viewscape: Viewscape Analysis

#' An S4 class to represent the viewshed
#'
#' A `viewshed` object contains a 'matrix' of visible and invisible area,
#' resolution, extent, and crs
#' @slot visible matrix
#' @slot resolution vector
#' @slot extent numeric
#' @slot crs character
#' @import methods
#' @importFrom terra geom
#' @md

setClass(
  Class = "Viewshed",
  representation(viewpoint = "numeric",
                 viewpos = "numeric",
                 visible = "matrix",
                 resolution = "numeric",
                 extent = "numeric",
                 crs = "character")
)

setGeneric("filter_invisible", function(object, ifRaster){
  standardGeneric("filter_invisible")
})

setMethod("filter_invisible", signature(object="Viewshed", ifRaster="logical"),
          function(object, ifRaster)
          {
            raster_data <- terra::rast(object@visible,
                                       crs = terra::crs(object@crs),
                                       extent = terra::ext(object@extent, xy = TRUE))
            if (ifRaster) {
              return(raster_data)
            } else {
              pointsData <- terra::as.points(raster_data)
              coords <- terra::geom(pointsData)
              x <- coords[,3]
              y <- coords[,4]
              z <- terra::values(pointsData)[,1]
              pt <- cbind(x, y, z)
              pt <- pt[pt[,3] > 0,]
              pt <- pt[,-3]
              return(pt)
            }
          })