Aspect (3D Analyst)
Summary
Derives aspect from a raster surface. The aspect identifies the downslope direction of the maximum rate of change in value from each cell to its neighbors.
Aspect can be thought of as the slope direction. The values of the output raster will be the compass direction of the aspect.
Illustration
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Aspect_3d (InRas1, OutRas) |
Usage
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Aspect is the direction of the maximum rate of change in the z-value from each cell in a raster surface.
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Aspect is expressed in positive degrees from 0 to 359.9, measured clockwise from north.
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Cells in the input raster that are flat—with zero slope—are assigned an aspect of -1.
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If the center cell in the immediate neighborhood (3 x 3 window) is NoData, the output is NoData.
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If any neighborhood cells are NoData, they are first assigned the value of the center cell, then the aspect is computed.
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.
Syntax
| Parameter | Explanation | Data Type |
in_raster |
The input surface raster. | Raster Layer |
out_raster |
The output aspect raster. | Raster Dataset |
Code Sample
This example creates an aspect raster from an input surface raster.
import arcpy
from arcpy import env
env.workspace = "C:/data"
arcpy.Aspect_3d("elevation", "C:/output/outaspect.img")
This example creates an aspect raster from an input surface raster.
# Name: Aspect_3d_Ex_02.py
# Description: Derives aspect from a raster surface.
# 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"
outAspect = "C:/output/outaspect2"
# Check out the ArcGIS 3D Analyst extension license
arcpy.CheckOutExtension("3D")
# Execute Aspect
arcpy.Aspect_3d(inRaster, outAspect)