update_focal: Update current focal for the next iteration

In spatialrisk: Calculating Spatial Risk

Update current focal for the next iteration

Description

Update current focal for the next iteration.

Usage

update_focal(old_focal, new_rasterized, extent, mw)

Arguments

old_focal	Focal obtained from terra::focal() for the current iteration.
new_rasterized	Output obtained from update_rasterize() for the next iteration.
extent	Extent of the cells corresponding to the coordinates with the highest concentration for the current iteration. Extent is output from terra::ext().
mw	Moving window obtained from create_mw().

Details

Spatial extent refers to the geographic area covered by a spatial dataset. It defines the boundaries in terms of its geographic coordinates (north, east, south, west).

An focal is updated by the following steps:

1. The extent of the cells corresponding to the coordinates with the highest concentration (xmin, xmax, ymin, ymax) is determined.

2. A buffer of size two times the radius plus the cell size around this extent. All cells within this new extent will impact the focal values.

3. Subset (crop) the rasterized data to include only the cells within this new extent. Perform focal calculations only for these new cells.

4. As the focal values of the cells near the borders may be inflated, crop the result again to include only the cells within a radius of the original extent.

5. Merge this updated focal with the previous focal object.

Author(s)

Martin Haringa

spatialrisk documentation built on June 8, 2025, 9:40 p.m.