Buffer (Analysis)

Summary

Creates buffer polygons around input features to a specified distance. An optional dissolve can be performed to combine overlapping buffers.

Learn more about how Buffer works

Illustration

Usage

• If buffering a projected feature class that has features covering a large region, or you are using a very large buffer distance, distortions in the projection can cause erroneous buffers to be produced.

  • Point or multipoint input—You can completely avoid distortion when buffering points by using a feature class that has a geographic coordinate system and specifying a Buffer Distance in linear units (meters, feet, and so forth, as opposed to angular units such as degrees). When this combination of inputs is used—point or multipoint features in a geographic coordinate system buffered by linear units—the output will be true geodesic buffers. Geodesic buffers appear as ovals on any flat map and will only appear as perfect circles when displayed on a globe (you can use the ArcGlobe or ArcGIS Explorer applications to view geographic data on a three-dimensional globe).
  • Line or polygon input—You can only minimize distortion by using a projection that minimizes distance distortion, such as an Equidistant Conic or an Azimuthal Equidistant projection.

  You can change the coordinate system of your input feature class by using the Project tool, or you can set the Output Coordinate System geoprocessing environment before executing the Buffer tool and this coordinate system will be used in creating buffers.

  For additional information, see How Buffer works.

• When buffering polygon features, negative buffer distances can be used to create buffers inside the polygon features. Using a negative buffer distance will reduce the polygons' boundaries by the distance specified.

  Caution:

  If the negative buffer distance is large enough to collapse the polygon to nothing, a null geometry will be generated. A warning message will be given, and any null geometry features will not be written to the output feature class.

• When the output of the Buffer tool will be used as input to an overlay operation such as Union or Intersect, it is recommended that the Dissolve Type option LIST or ALL be used to reduce the number of overlapping features produced by the tool. Use the Dissolve Type option LIST, and in Dissolve Field(s), select only the attributes from the input features that are necessary for the analysis being performed. This will reduce the number of spatial relationships between the datasets involved in the overlay operation, thereby reducing the amount of memory and time required for processing.

• Using the Dissolve Type option NONE adds the field BUFF_DIST to the output feature class. This field contains the buffer distance used to buffer each feature in the linear unit of the input features' coordinate system.

• If a field from the input features is used to obtain buffer distances, the field's values can be either a number (5) or a number with a valid linear unit (5 Kilometers). If the field values are simply a number, it is implied that these distances are in the linear unit of the input features' spatial reference. Field values can be entered with any valid linear unit and the feature will be buffered to that specified distance. If the linear unit specified in the field values is invalid or not recognized, the linear unit of the input features' spatial reference will be used by default.

  

• The Buffer tool can create very large multipart polygon features when the Dissolve Type option is set to ALL or LIST. This is especially true when using a dissolve field that has few unique values or when dissolving all polygons into a single polygon. Very large polygon features can cause display problems and poor performance when the features are drawn on a map or edited. To avoid these potential problems, use Multipart To Singlepart on the Buffer tool's output to split larger multipart features into many smaller features.

• For details on how the dissolve types ALL and LIST work, refer to the documentation for the Dissolve tool.

• Features are excluded from the buffer process if their buffer distance is zero.

• The buffered edges of a left or right side buffer are slightly different from those created by a full buffer due to differences in the algorithms used to create the buffers. The difference between the two is within the precision of the input features.

• The Dissolve Field(s) parameter Add Field button is used only in ModelBuilder. In ModelBuilder, where the preceding tool has not been run or its derived data does not exist, the Dissolve Field(s) parameter may not be populated with field names. The Add Field button allows expected fields to be added to the Dissolve Field(s) list in order to complete the Buffer tool dialog box.

License:

Side Type (line_side) options LEFT, RIGHT, and OUTSIDE_ONLY and the End Type (line_end_type) option FLAT are only available with an ArcInfo license.

Syntax

Buffer_analysis (in_features, out_feature_class, buffer_distance_or_field, {line_side}, {line_end_type}, {dissolve_option}, {dissolve_field})

Parameter	Explanation	Data Type
in_features	The input point, line, or polygon features to be buffered.	Feature Layer
out_feature_class	The feature class containing the output feature buffers.	Feature Class
buffer_distance_or_field	The distance around the input features in which buffer zones are created. Distances can be provided as either a value representing a linear distance or as a numeric field from the input features that contains the linear distances to buffer each feature. If the Distance linear units are not specified or are entered as Unknown, the linear unit of the input features' spatial reference is used.	Linear unit ; Field
line_side (Optional)	The side(s) of the input features that will be buffered. FULL —For line input features, buffers will be generated on both sides of the line. For polygon input features, buffers will be generated around the polygon and will contain and overlap the area of the input features. For point input features, buffers will be generated around the point. This is the default. LEFT —For line input features, buffers will be generated on the topological left of the line. This option is not valid for polygon input features. RIGHT —For line input features, buffers will be generated on the topological right of the line. This option is not valid for polygon input features. OUTSIDE_ONLY —For polygon input features, buffers will be generated only outside the input polygon (the area inside the input polygon will be erased from the output buffer). This option is not valid for line input features. License: This optional parameter is not available with an ArcView or ArcEditor license.	String
line_end_type (Optional)	The shape of the buffer at the end of line input features. This parameter is not valid for polygon input features. ROUND —The ends of the buffer will be round, in the shape of a half circle. This is the default. FLAT —The ends of the buffer will be flat, or squared, and will end at the endpoint of the input line feature. License: This optional parameter is not available with an ArcView or ArcEditor license.	String
dissolve_option (Optional)	Specifies the dissolve to be performed to remove output buffer overlap. NONE —An individual buffer for each feature is maintained, regardless of overlap. This is the default. ALL —All buffers are dissolved together into a single feature, removing any overlap. LIST —Any buffers sharing attribute values in the listed fields (carried over from the input features) are dissolved.	String
dissolve_field [dissolve_field,...] (Optional)	The list of field(s) from the input features on which to dissolve the output buffers. Any buffers sharing attribute values in the listed fields (carried over from the input features) are dissolved.	Field

Code Sample

Buffer Example (Python Window)

The following Python Window script demonstrates how to use the Buffer tool:

import arcpy
arcpy.env.workspace = "C:/data"
arcpy.Buffer_analysis("roads", "C:/output/majorrdsBuffered" "100 Feet", "FULL", "ROUND", "LIST", "Distance")

Buffer Example (Stand-alone Script)

Find areas of suitable vegetation that exclude areas heavily impacted by major roads:

# Name: Buffer.py
# Description: Find areas of suitable vegetation which exclude areas heavily impacted by major roads
# Author: ESRI

# import system modules 
import arcpy
from arcpy import env

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

# Select suitable vegetation patches from all vegetation
veg = "vegtype"
suitableVeg = "C:/output/Output.gdb/suitable_vegetation"
whereClause = "HABITAT = 1" 
arcpy.Select_analysis(veg, suitableVeg, whereClause)

# Buffer areas of impact around major roads
roads = "majorrds"
roadsBuffer = "C:/output/Output.gdb/buffer_output"
distanceField = "Distance"
sideType = "FULL"
endType = "ROUND"
dissolveType = "LIST"
dissolveField = "Distance"
arcpy.Buffer_analysis(roads, roadsBuffer, distanceField, sideType, endType, dissolveType, dissolveField)

# Erase areas of impact around major roads from the suitable vegetation patches
eraseOutput = "C:/output/Output.gdb/suitable_vegetation_minus_roads"
xyTol = "1 Meters"
arcpy.Erase_analysis(suitableVeg, roadsBuffer, eraseOutput, xyTol)

Environments

Default Output Z Value, M Resolution, M Tolerance, Output M Domain, Output XY Domain, Output Z Domain, Output Coordinate System, Extent, Current Workspace, Geographic Transformations, Scratch Workspace, Output has M values, Output has Z values, Output Spatial Grid 1, 2, 3, XY Resolution, XY Tolerance, Z Resolution, Z Tolerance

Licensing Information

ArcView: Yes

ArcEditor: Yes

ArcInfo: Yes