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Buffer (Analysis)
Release 9.3 Last modified January 11, 2011	Print all topics in : "Tools"

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NOTE: This topic was updated for 9.3.1.

Creates buffer polygons to a specified distance around the Input Features. An optional dissolve can be performed to remove overlapping buffers.

Learn more about how Buffer works.

Illustration

Buffer illustration

Usage tips

When the input is a point (or multipoint) dataset with geographic coordinate system (that is longitude and latitude coordinates) and the distance is specified in linear units (meters, feet, etc.), geodesic buffers will be generated. For details, see How Buffer works.
Features will be excluded from the buffer process if their buffer distance is zero.
Negative distances can be used when buffering polygon features to create buffers inside the polygon features. Using a negative value will reduce the area of the polygon feature by the distance specified. If the negative distance is large enough, a null geometry will be generated. These null geometry features are not written to the output feature class, and a warning message will be printed.
Side Type's LEFT and RIGHT options and End Type's FLAT as well as the OUTSIDE_ONLY option are only available with an ArcInfo license.
Using the Dissolve Type parameter's NONE option adds a BUFF_DIST field to the Output Feature Class. This field contains the buffer distance used to buffer each feature.
The buffered edges of a LEFT or RIGHT side buffer are different from those created by a FULL buffer due to differences in the algorithms used to create the buffers. When using the LEFT or RIGHT option, a vertex is placed at every degree along the point of rotation; the value is smaller using the FULL option, which creates a smoother line. The difference between the two is within the precision of the Input Features.
Buffer can create very large multipart polygon features when the Dissolve option is set to ALL or LIST. This is especially true when using a Dissolve Field(s), which has few unique values, or when dissolving all polygons into a single polygon. Very large polygon features may cause display problems and/or have poor performance when drawn on a map or when edited. To avoid these potential problems, use Multipart To Singlepart on Buffer's output to split larger multipart features into many smaller features.
When using the results of Buffer as input to an overlay operation such as Union or Intersect, it is recommended that Buffer output be dissolved in order to reduce the number of features and overlap. This can be done when only a subset of the Input Feature's attributes are necessary for the analysis being performed. This will reduce the number of spatial relationships between the input features being processed, thereby reducing the amount of memory the tool requires and the amount of time required for processing.
For details on how the Dissolve portion of the process works (when a Dissolve type other than NONE is specified), see the documentation for the Dissolve tool.
The Dissolve Fields 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 Fields parameter may not be populated with field names. The Add Field button allows you to add expected fields so you can complete the Buffer dialog box and continue to build your model.
Learn more about spatial reference and geoprocessing.
The following environment settings affect this tool: Coordinate system, Extent, XY Tolerance, Z Tolerance, M Tolerance, XY Resolution, Z Resolution, M Resolution, Output XY domain, Output Z domain, Output M domain, Output has M values, Output has Z values, Default Z value, Configuration keyword, Output Spatial Grid.

Command line syntax
An overview of the Command Line window
Buffer_analysis <in_features> <out_feature_class> <buffer_distance_or_field> {FULL | LEFT | RIGHT | OUTSIDE_ONLY} {ROUND | FLAT} {NONE | ALL | LIST} {dissolve_field;dissolve_field...}

Parameter	Explanation	Data Type
<in_features>	The feature layer or feature class to be buffered.	Feature Layer
<out_feature_class>	The feature class that will be created and to which the resulting features will be written.	Feature Class
<buffer_distance_or_field>	The distance used to create buffer zones around Input Features. Either a value or a numeric field can be used to provide buffer distances. If a negative buffer distance is specified, the buffer offsets will be generated inside, instead of outside, of the input features. This is only valid for polygon feature classes. If the distance units are not specified, or entered as Unknown, the units of the Input Features are used (or if the Output Coordinate System environment has been set, its units will be used).	Linear unit \| Field
{FULL \| LEFT \| RIGHT \| OUTSIDE_ONLY}	Options to buffer to one side of a line or outside polygons: FULL — A buffer will be generated on both sides of the line. If the input is a polygon, the result will include the area inside the polygon. This is the default. LEFT — The buffer will be generated on the LEFT side of the line. RIGHT — The buffer will be generated on the RIGHT side of the line. OUTSIDE_ONLY — The area inside the input polygon features will be excluded from the resulting buffer. These options are not available with an ArcView or ArcEditor license.	String
{ROUND \| FLAT}	For lines, the shape of the buffer at the line end points. ROUND — End will be in the shape of a half circle. This is the default. FLAT — Creates rectangular line endings with the middle of the short side of the rectangle coincident with the end point of the line. These options are not available with an ArcView or ArcEditor license. Line buffers will always have ROUND ends.	String
{NONE \| ALL \| LIST}	Specifies whether a dissolve will be performed to remove buffer feature overlap. NONE — Individual buffer for each feature is maintained, regardless of overlap. This is the default. ALL — Dissolves all the buffers together into a single feature and removes any overlap. LIST — Dissolves by a given list of fields.	String
{dissolve_field;dissolve_field...}	List of field(s) for the dissolve. Buffer polygons that share the same set of values in their Dissolve Field(s) will be dissolved together. The Add Field button, which is used only in ModelBuilder, allows you to add expected fields so you can complete the dialog box and continue to build your model.	Field

Data types for geoprocessing tool parameters

Command line example

Buffer_analysis c:\basedata\road.shp c:\basedata\buffered_roads.shp '200 Feet' FULL FLAT

Scripting syntax
About getting started with writing geoprocessing scripts
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 (Required)	The feature layer or feature class to be buffered.	Feature Layer
out_feature_class (Required)	The feature class that will be created and to which the resulting features will be written.	Feature Class
buffer_distance_or_field (Required)	The distance used to create buffer zones around Input Features. Either a value or a numeric field can be used to provide buffer distances. If a negative buffer distance is specified, the buffer offsets will be generated inside, instead of outside, of the input features. This is only valid for polygon feature classes. If the distance units are not specified, or entered as Unknown, the units of the Input Features are used (or if the Output Coordinate System environment has been set, its units will be used).	Linear unit \| Field
line_side (Optional)	Options to buffer to one side of a line or outside polygons: FULL — A buffer will be generated on both sides of the line. If the input is a polygon, the result will include the area inside the polygon. This is the default. LEFT — The buffer will be generated on the LEFT side of the line. RIGHT — The buffer will be generated on the RIGHT side of the line. OUTSIDE_ONLY — The area inside the input polygon features will be excluded from the resulting buffer. These options are not available with an ArcView or ArcEditor license.	String
line_end_type (Optional)	For lines, the shape of the buffer at the line end points. ROUND — End will be in the shape of a half circle. This is the default. FLAT — Creates rectangular line endings with the middle of the short side of the rectangle coincident with the end point of the line. These options are not available with an ArcView or ArcEditor license. Line buffers will always have ROUND ends.	String
dissolve_option (Optional)	Specifies whether a dissolve will be performed to remove buffer feature overlap. NONE — Individual buffer for each feature is maintained, regardless of overlap. This is the default. ALL — Dissolves all the buffers together into a single feature and removes any overlap. LIST — Dissolves by a given list of fields.	String
dissolve_field (Optional)	List of field(s) for the dissolve. Buffer polygons that share the same set of values in their Dissolve Field(s) will be dissolved together. The Add Field button, which is used only in ModelBuilder, allows you to add expected fields so you can complete the dialog box and continue to build your model.	Field

Data types for geoprocessing tool parameters

Script example

import arcgisscripting
gp = arcgisscripting.create()
gp.workspace = "c:/basedata"
gp.toolbox = "analysis"

# Buffer roads.shp based on each road feature's value in the Distance field,
#  and dissolve buffers into groups according to values from Road_Type field.
gp.buffer("roads.shp", "buffered_roads.shp", "Distance", "FULL", "ROUND", "LIST", "Road_Type")

Buffer (Analysis)

Command line example

Script example