Surface metrics

surface.aacf#

The areal autocorrelation function of a surface, geodiv's aacf: 1 at zero lag in the centre; on the largest square without missing cells around the centre when there are some.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the autocorrelation at every lag

surface.bearing#

The bearing area (Abbott-Firestone) curve of a surface, geodiv's bearing_area: the share of the surface at or above each height.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
table	table	bearing, height

surface.curvature#

A curvature of a surface (spatialEco's curvature): planform, profile, total, McNab's or Bolstad's.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the curvature

Setting	Type	What it is
type	text	planform (default), profile, total, mcnab, bolstad

surface.dissection#

Martonne's dissection (spatialEco's dissection): (z - min) / (max - min) in a window.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the dissection

Setting	Type	What it is
s	any	the window: odd cells, or [rows, columns] (5)

surface.fit_plane#

The trend of a surface: geodiv's least-squares polynomial of an order (0-6), or the best of order 0-3 (the residuals' smallest absolute mean); and the surface without it (remove_plane).

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
plane	map	the trend fitted
residuals	map	the surface less its trend

Setting	Type	What it is
order	any	0 to 6, or "best" (default)

surface.geomorphons#

Landforms of a DEM by geomorphons (Jasiewicz & Stepinski 2013), GRASS's r.geomorphon (8.4) bit for bit with four of its errors corrected, through landschaft's C++: from each cell the terrain is looked at along 8 directions up to the search radius; the signs (higher, level, lower) name the landform (1 flat, 2 peak, 3 ridge, 4 shoulder, 5 spur, 6 slope, 7 hollow, 8 footslope, 9 valley, 10 pit) and one of 498 patterns. A projected DEM.

Input	Type	What it is
demrequired	map	the DEM (projected; read as float32, as GRASS reads it)

Output	Type	What it is
forms	map	the landform of each cell, 1 to 10
ternary	map	the ternary pattern (0 to 6560, 498 codes)
positive	map	the directions higher than the threshold, as 8 bits
negative	map	the directions lower than the threshold, as 8 bits
share	table	form, cells, share
intensity	map	a measure of the geomorphon (with measures)
exposition	map	a measure of the geomorphon (with measures)
range	map	a measure of the geomorphon (with measures)
variance	map	a measure of the geomorphon (with measures)
elongation	map	a measure of the geomorphon (with measures)
azimuth	map	a measure of the geomorphon (with measures)
extend	map	a measure of the geomorphon (with measures)
width	map	a measure of the geomorphon (with measures)

Setting	Type	What it is
search	number	the outer search radius, in cells or map units (3)
skip	number	the inner radius not looked at (0)
flat	number	the flatness threshold, degrees (1)
dist	number	the flatness distance (0: none)
units	text	of search, skip and dist: cells (default) or map
comparison	text	how the angles decide a direction (anglev1)
extended	bool	the extended correction (-e): ridges, peaks, shoulders and footslopes looked at again within half the radius
measures	bool	also the measures (intensity, exposition...)

surface.gravity#

Gravitational interaction potential of source cells, Dinamica EGO's CalcInteractionPotentialMap (landschaft's): every cell the sum over the sources of their mass over the distance to them raised to the exponent, P = sum m / d^beta (a source's own cell at one cell); a pressure of towns, markets or roads, a driver of land change.

Input	Type	What it is
sourcesrequired	map	the masses (no value or 0: not a source)
mask	map	the potential is missing where this is

Output	Type	What it is
map	map	the potential

Setting	Type	What it is
exponent	number	the distance decay beta (2; 0: none)
unit	text	distances in cells (default, Dinamica's) or map units
method	text	direct (every pair, in a fixed order), fft (a convolution, about 1e-15 of the largest term off), or auto (default: direct up to 2000 sources or 1e8 pairs)

surface.hilltop#

Hilltops as permanent protection areas (APP de topo de morro, Lei 12.651/2012, art. 4, IX), landschaft's open implementation: every summit with its base (the saddle to higher terrain, the plain or water body it meets, or the lowest cell of its area), its height and slope; the hills at least min_height high and steeper than min_slope protected above base + fraction x height.

Input	Type	What it is
demrequired	map	the DEM (metres), projected or in longitude / latitude
plain	map	plains and water bodies (non-zero): a hill's base where met

Output	Type	What it is
app	map	1 in the upper part of the hills that qualify, 0 elsewhere
hill	map	the hill whose upper part holds each cell
hills	table	per summit, highest first: hill, x, y, top, base, base_kind (0 saddle, 1 plain, 2 lowest), base_x, base_y, height, mean_slope, line_slope, area, area_ha, qualifies, threshold, app_cells

Setting	Type	What it is
min_height	number	the least height of a hill, m (100)
min_slope	number	the slope a hill must exceed, degrees (25)
slope	text	mean (of the hill's cells, default) or line (summit to base)
fraction	number	where the APP starts, of the height (2/3)

surface.hli#

The heat load index (McCune & Keon's equations, spatialEco's hli) from the aspect and the slope; the latitude that of the map's centre unless given.

Input	Type	What it is
aspectrequired	map	the aspect
sloperequired	map	the slope

Output	Type	What it is
map	map	the HLI

Setting	Type	What it is
latitude	number	degrees (default: the map's centre's)
direct	bool	the direct radiation's folding (180° instead of 225°)
scaled	bool	exp of the index
units	text	degrees (default) or radians
hemisphere	text	northern (default) or southern
force_hemisphere	bool	the hemisphere as given (default true)
equation	integer	McCune & Keon's equation 1 (default), 2 or 3

surface.hsp#

The hierarchical slope position (spatialEco's hsp): the TPI summed over windows of growing scale.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the HSP

Setting	Type	What it is
min_scale	number	the first scale (3)
max_scale	number	the last scale (27)
inc	number	the scales' step (4)
win	text	rectangle (default) or circle
normalize	bool	normalised TPIs

surface.metrics#

Surface metrics of a continuous raster (an elevation, a canopy height, an NDVI...), ISO 25178 as the R package geodiv computes them, through landschaft's C++ (geodiv's bits): roughness and its distribution (amplitude), slopes and the area developed (hybrid), summits (features), the bearing area curve, the autocorrelation's lengths and directions and the fractal dimension (spatial). Usually of a surface with its trend removed. A table of one row.

Input	Type	What it is
maprequired	map	the surface (no value: missing)

Output	Type	What it is
table	table	a column per metric

Setting	Type	What it is
metrics	any	names (sa, sq, sku, sdr, sal...; default every one)

surface.peaks#

The peaks (or valleys) of a surface, geodiv's findpeaks: the cells higher (lower) than their 8 neighbours; a table of their centres, values, rows and columns.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
table	table	x, y, value, row, col

Setting	Type	What it is
valleys	bool	the valleys instead

surface.spherical_sd#

The spherical standard deviation of the surface's normals in a window (spatialEco's spherical.sd), or their variance.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the spherical standard deviation

Setting	Type	What it is
d	any	the window: odd cells, or [rows, columns] (3)
variance	bool	the variance instead

surface.srr#

The surface relief ratio (spatialEco's srr): (mean - min) / (max - min) in a window.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the SRR

Setting	Type	What it is
s	any	the window: odd cells, or [rows, columns] (5)

surface.terrain#

Slope or aspect of a surface as terra::terrain (Horn's 8 or 4 neighbours), through landschaft's C++; no value on the edge cells.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the slope or aspect

Setting	Type	What it is
v	text	slope (default) or aspect
unit	text	degrees (default) or radians
neighbors	integer	8 (default) or 4

surface.tpi#

The topographic position index (spatialEco's tpi): each cell's value less the mean of a window around it (a rectangle of cells, or a circle of a radius in map units).

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the TPI

Setting	Type	What it is
scale	number	the window: odd cells, or a circle's radius (3)
win	text	rectangle (default) or circle
normalize	bool	divided by the window's standard deviation

surface.trasp#

The transformed aspect (spatialEco's trasp): (1 - cos(aspect - 30°)) / 2, from 0 (north-northeast) to 1.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the TRASP

surface.tri#

The terrain ruggedness index (spatialEco's tri) in an odd window of cells.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the TRI

Setting	Type	What it is
s	any	the window: odd cells, or [rows, columns] (3)

surface.vrm#

The vector ruggedness measure (spatialEco's vrm): 1 less the length of the summed unit normals of a window over its cells.

Input	Type	What it is
maprequired	map	the surface (an elevation...)

Output	Type	What it is
map	map	the VRM

Setting	Type	What it is
s	any	the window: odd cells, or [rows, columns] (3)

surface.window#

Surface metrics in a moving window around every cell (landschaft's surface.window_metrics through its C++): the metrics of the window's surface at its centre, no value beyond the edges (and beyond window / 2 cells in a circle). A map per metric, in a stack.

Input	Type	What it is
maprequired	map	the surface

Output	Type	What it is
maps	stack	a map per metric, by its name

Setting	Type	What it is
metrics	any	names (default every one)
window	integer	the window's side in cells, odd, 3 or more (5)
shape	text	square (default) or circle