Hillshade (Spatial Analyst)

Summary

Creates a shaded relief from a surface raster by considering the illumination source angle and shadows.

Learn more about how Hillshade works

Illustration

OutRas = Hillshade(InRas1, 99, 33)

Usage

• The Hillshade tool creates a shaded relief raster from a raster. The illumination source is considered to be at infinity.

• The hillshade raster has an integer value range of 0 to 255.

• Two types of shaded relief rasters can be output. If the Model shadows option is disabled (unchecked), the output raster only considers local illumination angle. If it is enabled (checked), the output raster considers the effects of both local illumination angle and shadow.

• The analysis of shadows is done by considering the effects of the local horizon at each cell. Raster cells in shadow are assigned a value of zero.

• To create a raster of the shadow areas only, use the Con, Reclassify, or Extract by Attributes tool to separate the value zero from the other hillshade values. The Model shadows option must be enabled (checked) to create this result.

• If the input raster is in a spherical coordinate system, such as decimal degrees, the resulting hillshade may look peculiar. This is due to the difference in measure between the horizontal ground units and the elevation z units. Since the length of a degree of longitude changes with latitude, you will need to specify an appropriate z-factor for that latitude. If your x,y units are decimal degrees and your z units are meters, some appropriate z-factors for particular latitudes are:

      Latitude     Z-factor
       0           0.00000898
      10           0.00000912
      20           0.00000956
      30           0.00001036
      40           0.00001171
      50           0.00001395
      60           0.00001792
      70           0.00002619
      80           0.00005156

• When the input raster needs to be resampled, the bilinear technique will be used. An example of when an input raster may be resampled is when the output coordinate system, extent, or cell size is different from that of the input.

• See Analysis environments and Spatial Analyst for additional details on the geoprocessing environments that apply to this tool.

Parameters

Dialog

Label	Explanation	Data Type
Input raster	The input surface raster.	Raster Layer
Azimuth (Optional)	Azimuth angle of the light source. The azimuth is expressed in positive degrees from 0 to 360, measured clockwise from north. The default is 315 degrees.	Double
Altitude (Optional)	Altitude angle of the light source above the horizon. The altitude is expressed in positive degrees, with 0 degrees at the horizon and 90 degrees directly overhead. The default is 45 degrees.	Double
Model shadows (Optional)	Type of shaded relief to be generated. Unchecked—The output raster only considers local illumination angles; the effects of shadows are not considered. The output values can range from 0 to 255, with 0 representing the darkest areas, and 255 the brightest. This is the default. Checked—The output shaded raster considers both local illumination angles and shadows. The output values range from 0 to 255, with 0 representing the shadow areas, and 255 the brightest.	Boolean
Z factor (Optional)	The number of ground x,y units in one surface z-unit. The z-factor adjusts the units of measure for the z-units when they are different from the x,y units of the input surface. The z-values of the input surface are multiplied by the z-factor when calculating the final output surface. If the x,y units and z-units are in the same units of measure, the z-factor is 1. This is the default. If the x,y units and z-units are in different units of measure, the z-factor must be set to the appropriate factor or the results will be incorrect. For example, if the z-units are feet and the x,y units are meters, use a z-factor of 0.3048 to convert the z-units from feet to meters (1 foot = 0.3048 meter).	Double

Return Value

Label	Explanation	Data Type
Output raster	The output hillshade raster. The hillshade raster has an integer value range of 0 to 255.	Raster

Python

Hillshade(in_raster, {azimuth}, {altitude}, {model_shadows}, {z_factor})

Name	Explanation	Data Type
in_raster	The input surface raster.	Raster Layer
azimuth (Optional)	Azimuth angle of the light source. The azimuth is expressed in positive degrees from 0 to 360, measured clockwise from north. The default is 315 degrees.	Double
altitude (Optional)	Altitude angle of the light source above the horizon. The altitude is expressed in positive degrees, with 0 degrees at the horizon and 90 degrees directly overhead. The default is 45 degrees.	Double
model_shadows (Optional)	Type of shaded relief to be generated. NO_SHADOWS—The output raster only considers local illumination angles; the effects of shadows are not considered.The output values can range from 0 to 255, with 0 representing the darkest areas, and 255 the brightest. This is the default. SHADOWS—The output shaded raster considers both local illumination angles and shadows.The output values range from 0 to 255, with 0 representing the shadow areas, and 255 the brightest.	Boolean
z_factor (Optional)	The number of ground x,y units in one surface z-unit. The z-factor adjusts the units of measure for the z-units when they are different from the x,y units of the input surface. The z-values of the input surface are multiplied by the z-factor when calculating the final output surface. If the x,y units and z-units are in the same units of measure, the z-factor is 1. This is the default. If the x,y units and z-units are in different units of measure, the z-factor must be set to the appropriate factor or the results will be incorrect. For example, if the z-units are feet and the x,y units are meters, use a z-factor of 0.3048 to convert the z-units from feet to meters (1 foot = 0.3048 meter).	Double

Return Value

Name	Explanation	Data Type
out_raster	The output hillshade raster. The hillshade raster has an integer value range of 0 to 255.	Raster

Code sample

Hillshade example 1 (Python window)

This example generates a hillshade raster that includes shadows. Specific azimuth and altitude angles are set.

import arcpy
from arcpy import env
from arcpy.sa import *
env.workspace = "C:/sapyexamples/data"
outHillshade = Hillshade("elevation", 180, 75, "SHADOWS", 1)
outHillshade.save("C:/sapyexamples/output/outhillshd01")

Hillshade example 2 (stand-alone script)

This example generates a hillshade raster that includes shadows. Specific azimuth and altitude angles are set and a z-factor is used to convert z-units from feet to meters.

# Name: Hillshade_Ex_02.py
# Description: Computes hillshade values for a raster surface.
# Requirements: Spatial Analyst Extension

# Import system modules
import arcpy
from arcpy import env
from arcpy.sa import *

# Set environment settings
env.workspace = "C:/sapyexamples/data"

# Set local variables
inRaster = "elevation"
azimuth = 180
altitude = 75
modelShadows = "SHADOWS"
zFactor = 0.348

# Execute HillShade
outHillShade = Hillshade(inRaster, azimuth, altitude, modelShadows, zFactor)

# Save the output 
outHillShade.save("C:/sapyexamples/output/outhillshd02")

Environments

Auto Commit, Cell Size, Cell Size Projection Method, Compression, Current Workspace, Extent, Geographic Transformations, Mask, Output CONFIG Keyword, Output Coordinate System, Scratch Workspace, Snap Raster, Tile Size