Calculate DEM Curvature

Feature Description

Calculates curvature values for DEM raster data surfaces, including mean curvature, profile curvature and plan curvature. Curvature is the second derivative of the surface, or the slope of the slope. The output result represents the surface curvature of each cell in the terrain raster, obtained by fitting the cell with its eight neighboring cells and calculating the curvature at position (0,0) of the fitted surface. The result outputs raster datasets for three curvature types: mean curvature, profile curvature and plan curvature.

  • Mean Curvature: The average of two mutually perpendicular orthogonal curvatures at a point on the surface, measuring the degree of bending of the terrain surface in space.
  • Profile Curvature: Measures the rate of elevation change along the maximum slope direction, representing the rate of slope change and reflecting topographic variation characteristics.
  • Plan Curvature: Measures the rate of elevation change perpendicular to the maximum slope direction, representing the curvature of the horizontal cross-section curve through a surface point. Reflects horizontal variation characteristics of the terrain.

Result explanation:

  • The three generated curvature datasets maintain the same extent and resolution as the original dataset.
  • In the result datasets: Positive values indicate convex surfaces, negative values indicate concave surfaces, and zero values represent flat surfaces.
  • Curvature values are expressed in 1/100 of the z-unit. Typical values range between -0.5 to 0.5 for gentle terrains, and -4 to 4 for steep terrains. Note that some surfaces may exceed these ranges.

Feature Entry

  • Spatial Analysis Tab -> Raster Analysis -> Surface Analysis -> DEM Curvature Calculation
  • Toolbox -> Raster Analysis Tools -> Surface Analysis -> Terrain Calculation -> DEM Curvature Calculation

Parameter Description

  • Source Data Settings (DEM raster dataset for calculation)
    • Datasources: Lists all datasources in the current workspace. Select the datasource containing the input raster dataset.
    • Dataset: Lists all raster datasets in the selected datasource. Automatically locates the dataset if preselected in Workspace Manager.
    • Elevation Scaling Factor: Converts z-unit to match x/y units. For example, use 0.3048 when converting feet to meters. Default value 1 means no scaling.
  • Result Data Settings (Output curvature datasets)
    • Datasources: Select output datasource (default matches source datasource).
    • Mean Curvature Dataset: Output dataset name for mean curvature (default: AverageCurvature).
    • Profile Curvature Dataset: Output dataset name for profile curvature (default: ProfileCurvature).
    • Plan Curvature Dataset: Output dataset name for plan curvature (default: PlanCurvature).
Caution:
  1. When elevation units cannot be converted through fixed scaling (e.g., geographic coordinates in degrees with elevation in meters), reproject DEM to planar coordinates first.
  2. Edge cells use their own elevation values for out-of-bounds neighbors in 3×3 neighborhood calculations, potentially producing underestimated curvature values. NoData cells are treated similarly.
  3. Profile and plan curvature datasets are optional (empty names skip generation). Mean curvature dataset is mandatory and requires a valid name.

Related Topics

Surface Analysis Overview