Surface Area Ratio (Spatial Analyst Tools)
Summary
Calculates a surface area to planar area ratio for each cell of a raster surface.
Usage
The cell values of the output raster represent the ratio between the 3D surface area and the 2D planar area at each cell location. This ratio is a rugosity index that can be used to model the seafloor or land surface structural complexity.
The Input Surface Raster parameter value can be bathymetry or topographic digital elevation model data.
The Planar Area Type parameter supports two types of 2D planar area, horizontal and arc-chord.
When the Horizontal option is selected, the tool will use the cell area projected on the horizontal plane as the 2D planar area. When the Arc-Chord option is selected, the 2D planar area will be the cell area projected on the plane of best fit calculated in a 3 by 3 cell neighborhood. In this case, the output surface area ratio value will be decoupled from the effect of local slope, which is known as an arc-chord rugosity index (Du Preez, 2015).
If the height value of the input surface raster is in a different unit than the XY unit, it will be internally converted to the XY unit before it is used. For the optional Output Surface Area Raster parameter value, the units are the XY unit squared. For example, if the XY unit of the input surface raster is meters, the area unit of the output surface area raster values will be square meters.
Specifying the surface Z Unit parameter value ensures the proper computation of the surface area.
If a z unit is available in the vertical coordinate system of the input raster, it will be applied automatically. It is recommended that you define a z unit for the input raster if it is missing. You can use the Define Projection tool to specify a z unit. If it is undefined, meter will be used by default.
When the output raster format is
.crf, this tool supports the Pyramid raster storage environment. Pyramids will be created in the output by default. For any other output format, this environment is not supported, and pyramids will not be created.See Analysis environments and Spatial Analyst for additional details on the geoprocessing environments that apply to this tool.
Parameters
| Label | Explanation | Data type |
|---|---|---|
|
Input Surface Raster |
The input surface raster. |
Raster Layer |
|
Output Surface Area Raster (Optional) |
The output surface area raster. This output raster stores the 3D surface area at each cell location. |
Raster Dataset |
|
Z Unit (Optional) |
Specifies the linear unit that will be used for vertical z-values. It is defined by a vertical coordinate system if it exists. If no vertical coordinate system exists, define the z-unit using the unit list to ensure correct geodesic computation. The default is meter.
|
String |
|
Planar Area Type (Optional) |
Specifies the type of 2D planar area that will be used in surface area ratio calculation.
|
String |
Return value
| Label | Explanation | Data type |
|---|---|---|
|
Output Raster |
The output surface area ratio raster. |
Raster |
Environments
Auto Commit, Cell Size, Cell Size Projection Method, Compression, Current Workspace, Extent, Geographic Transformations, Mask, Output CONFIG Keyword, Output Coordinate System, Parallel Processing Factor, Pyramid, Scratch Workspace, Snap Raster, Tile Size
Licensing information
- Basic: Requires Spatial Analyst
- Standard: Requires Spatial Analyst
- Advanced: Requires Spatial Analyst
References
Du Preez, C. "A new arc-chord ratio (ACR) rugosity index for quantifying three-dimensional landscape structural complexity". Landscape Ecology, 2015, 30, 181-192.