xrspatial.terrain_metrics.tri

xrspatial.terrain_metrics.tri(agg: DataArray, name: str | None = 'tri', boundary: str = 'nan') → DataArray

Compute the Terrain Ruggedness Index (TRI) for each cell.

TRI quantifies local elevation variation as the square root of the sum of squared differences between the center cell and its 8 neighbors in a 3x3 window (Riley et al. 1999).

Parameters:

• agg (xarray.DataArray or xr.Dataset) – 2D NumPy, CuPy, NumPy-backed Dask, or CuPy-backed Dask xarray DataArray of elevation values. If a Dataset is passed, the operation is applied to each data variable independently.

• name (str, default='tri') – Name of output DataArray.

• boundary (str, default='nan') – How to handle edges where the kernel extends beyond the raster. 'nan' - fill missing neighbours with NaN (default). 'nearest' - repeat edge values. 'reflect' - mirror at boundary. 'wrap' - periodic / toroidal.

Returns:

2D array of TRI values with the same shape, coords, dims, and attrs as the input.

Return type:

xarray.DataArray or xr.Dataset

References

Riley, S.J., DeGloria, S.D. and Elliot, R. (1999). A Terrain Ruggedness Index that Quantifies Topographic Heterogeneity. Intermountain Journal of Sciences, 5(1-4), 23-27.