Fractal dimension index (Shape metric)
lsm_p_frac(landscape, directions = 8)tibble
Raster* Layer, Stack, Brick, SpatRaster (terra), stars, or a list of rasterLayers.
The number of directions in which patches should be connected: 4 (rook's case) or 8 (queen's case).
$$FRAC = \frac{2 * \ln * (0.25 * p_{ij})} {\ln a_{ij}}$$ where \(p_{ij}\) is the perimeter in meters and \(a_{ij}\) is the area in square meters
FRAC is a 'Shape metric'. The index is based on the patch perimeter and the patch area and describes the patch complexity. Because it is standardized, it is scale independent, meaning that increasing the patch size while not changing the patch form will not change the ratio.
None
1 <= FRAC <= 2
Approaches FRAC = 1 for a squared patch shape form and FRAC = 2 for a irregular patch shape.
McGarigal, K., SA Cushman, and E Ene. 2012. FRAGSTATS v4: Spatial Pattern Analysis Program for Categorical and Continuous Maps. Computer software program produced by the authors at the University of Massachusetts, Amherst. Available at the following web site: https://www.umass.edu/landeco/
Mandelbrot, B. B. 1977. Fractals: Form, Chance, and Dimension. San Francisco. W. H. Freeman and Company.
lsm_p_area,
lsm_p_perim,
lsm_c_frac_mn,
lsm_c_frac_sd,
lsm_c_frac_cv,
lsm_l_frac_mn,
lsm_l_frac_sd,
lsm_l_frac_cv