Buffer (Analysis)

Summary

Creates buffer polygons around input features to a specified distance.

Alternate tools are available for buffer operations. See the Pairwise Buffer and Graphic Buffer tool documentation for details.

Learn more about how Buffer works

Illustration

Usage

• As described in How Buffer works, an important feature of the Buffer tool is the Method parameter, which specifies how buffers will be constructed. The two basic methods for constructing buffers, Euclidean and geodesic, are described as follows:

  • Euclidean buffers measure distance in a two-dimensional Cartesian plane, where distances are calculated between two points on a flat surface. Euclidean buffers are appropriate when analyzing distances around features in a projected coordinate system in a relatively small area (such as one UTM zone).
  • Geodesic buffers account for the shape of the earth (an ellipsoid, or more properly, a geoid). Distances are calculated between two points on a curved surface (the geoid). You should create geodesic buffers in the following circumstances:
    • The input features are dispersed (cover multiple UTM zones, large regions, or even the entire globe).
    • The spatial reference (map projection) of your input features distorts distances to preserve other properties such as area.
    Geodesic buffers may appear unusual on a flat map. When displayed on a globe, however, these buffers will look correct. For more information, see How Buffer works.

  The Method parameter specifies how buffers will be created.

  • The Planar option is the default. This option will automatically determine which method to use based on the coordinate system of the input.
    • If the input features have a projected coordinate system, Euclidean buffers will be created.
    • If the input features have a geographic coordinate system and you specify a Buffer Distance value in linear units (meters, feet, and so forth, as opposed to angular units such as degrees), geodesic buffers will be created.
    • This option produces the same result as the Buffer tool prior to ArcGIS 10.3.
  • The Geodesic option creates a shape-preserving geodesic buffer for any input coordinate system. The input features are densified to create buffers that more accurately represent the shape of the input features. In some cases, this option may take more time than a geodesic buffer created using the Planar option. However, the result is a buffer that more accurately matches the shape of the input feature.

  Note:

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

  When using the Planar method, you can improve the accuracy of buffers created with projected inputs using a projection that minimizes distance distortion, such as an Equidistant Conic or an Azimuthal Equidistant projection, and is geographically appropriate for your input.

• If the input is a projected coordinate system and the output is a geodatabase feature class, the output may contain circular arc segments. When the input is a point feature class, the output will always be circular arcs. If circular arcs are projected to a different coordinate system, the location and size of the original buffers will be transformed. The shape of the buffers will not change, and the projected buffers will not accurately represent the area covered by the original buffer. If you project circular arcs, use the Densify tool to convert the circular arcs to straight lines; then project the densified buffers.

• The output feature class will include a BUFF_DIST field that contains the buffer distance used to buffer each feature in the linear unit of the input's coordinate system. When using the Geodesic method to create buffers, the buffer distance entered will be converted to meters.

  If a field named BUFF_DIST exists in the input, its values will be overwritten in the output. If a Dissolve Type value of All or List is used, the output will not include this field.

• The output feature class will include a ORIG_FID field that contains the feature ID of the input feature for which the buffer was created. If a field named ORIG_FID exists in the input, its values will be overwritten in the output. If a Dissolve Type value of All or List is used, the output will not include this field.

• 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 appear, and no null geometry features will be written to the output feature class.

• If a field from the input is used to obtain buffer distances, the field's values can be either a number (5, for example) or a number with a valid linear unit (5 kilometers, for example). If a field value is a number, it is assumed that the distance is in the linear unit of the input's spatial reference (unless the input is in a geographic coordinate system, in which case, the value is assumed to be in meters). If the linear unit specified in the field values is invalid or not recognized, the linear unit of the input's spatial reference will be used by default.

  

• The Add Field button in the Dissolve Field(s) parameter is used only in ModelBuilder. In ModelBuilder, when 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 you to add expected fields to the Dissolve Field(s) list to complete the Buffer tool dialog box.

• Buffer operations do not support the transfer of z-values from the input to the output buffer features.

• Buffer operations do not support the transfer of m-values from the input to the output buffer features.

License:

The Side Type parameter options Left, Right, and Exclude the input polygon from buffer and the End Type parameter option Flat are only available with an Desktop Advanced license.

Parameters

Dialog

Label	Explanation	Data Type
Input Features	The input point, line, or polygon features to be buffered.	Feature Layer
Output Feature Class	The feature class containing the output buffers.	Feature Class
Distance [value or field]	The distance around the input features that will be buffered. Distances can be provided as either a value representing a linear distance or as a field from the input features that contains the distance to buffer each feature. If linear units are not specified or are entered as Unknown, the linear unit of the input features' spatial reference will be used.	Linear Unit; Field
Side Type (Optional)	Specifies the sides of the input features that will be buffered. This parameter is only supported for polygon and line features. Full—For lines, buffers will be generated on both sides of the line. For polygons, buffers will be generated around the polygon and will contain and overlap the area of the input features. This is the default. Left—For lines, buffers will be generated on the topological left of the line. This option is not supported for polygon input features. Right—For lines, buffers will be generated on the topological right of the line. This option is not supported for polygon input features. Exclude the input polygon from buffer—For polygons, buffers will be generated outside the input polygon only (the area inside the input polygon will be erased from the output buffer). This option is not supported for line input features. License: This optional parameter is not available with a Desktop Basic or Desktop Standard license.	String
End Type (Optional)	Specifies 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 a Desktop Basic or Desktop Standard license.	String
Dissolve Type (Optional)	Specifies the type of dissolve that will be performed to remove buffer overlap. No Dissolve—An individual buffer for each feature will be maintained, regardless of overlap. This is the default. Dissolve all output features into a single feature—All buffers will be dissolved together into a single feature, removing any overlap. Dissolve features using the listed fields' unique values or combination of values—Any buffers sharing attribute values in the listed fields (carried over from the input features) will be dissolved.	String
Dissolve Field(s) (Optional)	The list of fields from the input features on which the output buffers will be dissolved. Any buffers sharing attribute values in the listed fields (carried over from the input features) will be dissolved.	Field
Method (Optional)	Specifies whether the planar or geodesic method will be used to create the buffers. Planar—If the input features are in a projected coordinate system, Euclidean buffers will be created. If the input features are in a geographic coordinate system and the buffer distance is in linear units (meters, feet, and so forth, as opposed to angular units such as degrees), geodesic buffers will be created. This is the default. You can use the Output Coordinate System environment setting to specify the coordinate system to use. For example, if your input features are in a projected coordinate system, you can set the environment to a geographic coordinate system to create geodesic buffers. Geodesic (shape preserving)—All buffers will be created using a shape-preserving geodesic buffer method, regardless of the input coordinate system.	String

Python

arcpy.analysis.Buffer(in_features, out_feature_class, buffer_distance_or_field, {line_side}, {line_end_type}, {dissolve_option}, {dissolve_field}, {method})

Name	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 buffers.	Feature Class
buffer_distance_or_field	The distance around the input features that will be buffered. Distances can be provided as either a value representing a linear distance or as a field from the input features that contains the distance to buffer each feature. If linear units are not specified or are entered as Unknown, the linear unit of the input features' spatial reference will be used. When specifying a distance, if the desired linear unit has two words, such as Decimal Degrees, combine the two words into one (for example, 20 DecimalDegrees).	Linear Unit; Field
line_side (Optional)	Specifies the sides of the input features that will be buffered. This parameter is only supported for polygon and line features. FULL—For lines, buffers will be generated on both sides of the line. For polygons, buffers will be generated around the polygon and will contain and overlap the area of the input features. This is the default. LEFT—For lines, buffers will be generated on the topological left of the line. This option is not supported for polygon input features. RIGHT—For lines, buffers will be generated on the topological right of the line. This option is not supported for polygon input features. OUTSIDE_ONLY—For polygons, buffers will be generated outside the input polygon only (the area inside the input polygon will be erased from the output buffer). This option is not supported for line input features. License: This optional parameter is not available with a Desktop Basic or Desktop Standard license.	String
line_end_type (Optional)	Specifies 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 a Desktop Basic or Desktop Standard license.	String
dissolve_option (Optional)	Specifies the type of dissolve that will be performed to remove buffer overlap. NONE—An individual buffer for each feature will be maintained, regardless of overlap. This is the default. ALL—All buffers will be 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) will be dissolved.	String
dissolve_field [dissolve_field,...] (Optional)	The list of fields from the input features on which the output buffers will be dissolved. Any buffers sharing attribute values in the listed fields (carried over from the input features) will be dissolved.	Field
method (Optional)	Specifies whether the planar or geodesic method will be used to create the buffers. PLANAR—If the input features are in a projected coordinate system, Euclidean buffers will be created. If the input features are in a geographic coordinate system and the buffer distance is in linear units (meters, feet, and so forth, as opposed to angular units such as degrees), geodesic buffers will be created. This is the default. You can use the Output Coordinate System environment setting to specify the coordinate system to use. For example, if your input features are in a projected coordinate system, you can set the environment to a geographic coordinate system to create geodesic buffers. GEODESIC—All buffers will be created using a shape-preserving geodesic buffer method, regardless of the input coordinate system.	String

Code sample

Buffer example 1 (Python window)

The following Python window script demonstrates how to use the Buffer function.

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

Buffer example 2 (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 that exclude areas heavily 
# impacted by major roads

# Import system modules 
import arcpy

# Set environment settings
arcpy.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.analysis.Select(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.analysis.Buffer(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.analysis.Erase(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, Parallel Processing Factor, Current Workspace, Geographic Transformations, Scratch Workspace, Output has M values, Output has Z values, XY Resolution, XY Tolerance, Z Resolution, Z Tolerance

Special cases

Parallel Processing Factor

This tool honors the Parallel Processing Factor environment. If the environment is not set (the default) or is set to 0, parallel processing will be disabled. Setting the environment to 100 will enable parallel processing. Up to 10 cores will be used when parallel processing is enabled.

The Parallel Processing Factor environment is only supported when buffering line and polygon features.

Licensing information

• Basic: Limited
• Standard: Limited
• Advanced: Yes