Slope (3D Analyst)
Summary
Identifies the slope (gradient, or rate of maximum change in zvalue) from each cell of a raster surface.
Illustration
Usage

Slope is the rate of maximum change in zvalue from each cell.

The use of a zfactor is essential for correct slope calculations when the surface z units are expressed in units different from the ground x,y units.

The range of values in the output depends on the type of measurement units.
 For degrees, the range of slope values is 0 to 90.
 For percent rise, the range is 0 to essentially infinity. A flat surface is 0 percent, a 45 degree surface is 100 percent, and as the surface becomes more vertical, the percent rise becomes increasingly larger. See how Slope works for a more detailed explanation of the range of output values with this option.

If the center cell in the immediate neighborhood (3 x 3 window) is NoData, the output is NoData.

If any neighborhood cells are NoData, they are assigned the value of the center cell; then the slope is computed.
Syntax
Parameter  Explanation  Data Type 
in_raster 
The input surface raster.  Raster Layer 
out_raster 
The output slope raster.  Raster Dataset 
output_measurement (Optional) 
Determines the measurement units (degrees or percentages) of the output slope data.
 String 
z_factor (Optional)  Number of ground x,y units in one surface z unit. The zfactor adjusts the units of measure for the z units when they are different from the x,y units of the input surface. The zvalues of the input surface are multiplied by the zfactor when calculating the final output surface. If the x,y units and z units are in the same units of measure, the zfactor is 1. This is the default. If the x,y units and z units are in different units of measure, the zfactor must be set to the appropriate factor, or the results will be incorrect. For example, if your z units are feet and your x,y units are meters, you would use a zfactor of 0.3048 to convert your z units from feet to meters (1 foot = 0.3048 meter).  Double 
Code Sample
This example determines the slope values of the input surface raster.
import arcpy from arcpy import env env.workspace = "C:/data" arcpy.Slope_3d("elevation", "C:/output/outslope01", "DEGREE", 0.3043)
This example determines the slope values of the input surface raster.
# Name: Slope_3d_Ex_02.py # Description: Identifies the rate of maximum change # in zvalue from each cell. # Requirements: 3D Analyst Extension # Import system modules import arcpy from arcpy import env # Set environment settings env.workspace = "C:/data" # Set local variables inRaster = "elevation" outRaster = "C:/output/outslope02" outMeasurement = "DEGREE" zFactor = 0.3043 # Check out the ArcGIS 3D Analyst extension license arcpy.CheckOutExtension("3D") # Execute Slope arcpy.Slope_3d(inRaster, outRaster, outMeasurement, zFactor)