skyviewtopo: calculates the proportion of sky in view

In ilyamaclean/microclima: microclimate modelling with R

calculates the proportion of sky in view

Description

skyviewtopo is used to calculate a coefficient to correct for the proportion of sky in view when calculating net shortwave or longwave radiation above the canopy.

Usage

skyviewtopo(dtm, steps = 36, reso = 100)

Arguments

dtm	dtm a SpatRaster object, two-dimensional array or matrix of elevations (m).
steps	an optional integer. The sky view is calculated from the horizon angle in specified directions. Steps defines the total number of directions used. If the default 36 is specified, then the horizon angle is calculated at 10º intervals.
reso	a single numeric value representing the spatial resolution of dtm (m).

Details

If a proportion of the sky of partially obscured, then the isotropic radiation flux received by a surface can be determined by integrating the single direction radiation flux over the proportion of sky in view. This function returns the integrated flux over the proportion of sky in view expressed as a proportion of the integrated flux over the entire hemisphere.

If dtm is a SpatRaster object, a SpatRaster object is returned. The projection system associated with dtm must be such that units of x, y and z are identical. Use terra::project() to convert the projection to a Universal Transverse Mercator type projection system.

Value

a SpatRaster object or two-dimension array of values representing the proportion of isotropic radiation received by a partially obscured surface relative to the full hemisphere.

See Also

The function skyviewveg() calculates a sky view correction factor underneath vegetation.

Examples

library(terra)
sv <- skyviewtopo(rast(dtm100m))
plot(sv, main = "Sky view factor")

ilyamaclean/microclima documentation built on Sept. 5, 2024, 8:37 p.m.