![]() 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 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). A warning message will appear, and no null geometry features will be written to the output feature class. If the negative buffer distance is large enough to collapse the polygon to nothing, a null geometry will be generated. Using a negative buffer distance will reduce the polygons' boundaries by the distance specified. When buffering polygon features, negative buffer distances can be used to create buffers inside the polygon features. If a Dissolve Type value of All or List is used, the output will not include this field. If a field named ORIG_FID exists in the input, its values will be overwritten in the output. 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 BUFF_DIST exists in the input, its values will be overwritten in the output. When using the Geodesic method to create buffers, the buffer distance entered will be converted to meters. 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. If you project circular arcs, use the Densify tool to convert the circular arcs to straight lines then project the densified buffers. The shape of the buffers will not change, and the projected buffers will not accurately represent the area covered by the original buffer. If circular arcs are projected to a different coordinate system, the location and size of the original buffers will be transformed. When the input is a point feature class, the output will always be circular arcs. If the input is a projected coordinate system and the output is a geodatabase feature class, the output may contain circular arc segments. 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. 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. However, the result is a buffer that more accurately matches the shape of the input feature. In some cases, this option may take more time than a geodesic buffer created using the Planar option. The input features are densified to create buffers that more accurately represent the shape of the input features.
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