CONTIG (patch level)
Contiguity index (Shape metric)
lsm_p_contig(landscape, directions = 8)
landscape |
Raster* Layer, Stack, Brick, SpatRaster (terra), stars, or a list of rasterLayers. |
directions |
The number of directions in which patches should be connected: 4 (rook's case) or 8 (queen's case). |
CONTIG = \frac{\Bigg[\frac{∑\limits_{r=1}^z c_{ijr}}{a_{ij}}\Bigg] - 1 }{ v - 1}
where c_{ijr} is the contiguity value for pixel r in patch ij, a_{ij} the area of the respective patch (number of cells) and v is the size of the filter matrix (13 in this case).
CONTIG is a 'Shape metric'. It asses the spatial connectedness (contiguity) of cells in patches. CONTIG coerces patch values to a value of 1 and the background to NA. A nine cell focal filter matrix:
filter_matrix <- matrix(c(1, 2, 1,
2, 1, 2,
1, 2, 1), 3, 3, byrow = T)... is then used to weight orthogonally contiguous pixels more heavily than diagonally contiguous pixels. Therefore, larger and more connections between patch cells in the rookie case result in larger contiguity index values.
None
0 >= CONTIG <= 1
Equals 0 for one-pixel patches and increases to a limit of 1 (fully connected patch).
tibble
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: http://www.umass.edu/landeco/research/fragstats/fragstats.html
LaGro, J. 1991. Assessing patch shape in landscape mosaics. Photogrammetric Engineering and Remote Sensing, 57(3), 285-293
lsm_p_contig(landscape)
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