There is a known performance issue when the ArcMap Buffer Wizard is used to create multiple rings around each feature, or ring buffers, together with the option to dissolve overlapping buffers. The problem is most noticeable when buffering many features.

This happens because dissolving buffers requires that overlapping buffer polygons be clipped, which is a geoprocessing operation. With ring buffers this operation becomes even more memory intensive. As the computer runs out of RAM and starts to use swap memory, the buffering process slows down considerably.

To cut down on processing time do either or both of the following:

• If creating buffers simply for display purposes, create separate buffers for each distance and order these in the Table of Contents (TOC). Organize the TOC so that the smaller distance buffers display on top of the larger distance buffers.
• Change the buffer shape type from Rings to Disks using the ArcMap Advanced Settings Utility.

When two features classes in a personal geodatabase (PGDB) are unioned using the geoprocessing UNION Tool the result is a new feature class in the same personal geodatabase with features that are slightly shifted from the positions of original features.

There are 2 possible reasons:
1. The input feature classes are not contained in a feature dataset.
2. The feature classes have different precision values.

Feature coordinates are snapped to an invisible, underlaying grid that is calculated internally based on the feature class X/Y domain and precision values. The grid for a feature class with precision of 10 will be different than the grid for a second feature class that has a precision of 100.

The overlay function calculates a new precision value for the output feature class based on the extents (X/Y Domain) and other factors from all input feature classes. This results in a different location for the underlaying grid and features that are slightly shifted.

Place all input feature classes into a feature dataset and direct the output feature class into the same feature dataset. X/Y Domain and Precision values are stored at the feature dataset level. Feature coordinates of all feature classes that are stored within a feature dataset will be snapped to the same positions.

When using the Buffer Wizard in ArcMap to buffer points, the output buffers are not round.

By default, ArcMap uses the Hotine Projection to calculate buffers. This projection is only appropriate for a small buffer radius of less than five miles and low latitudes. When using a large buffer radius or buffering data at high latitudes, this default projection is unsuitable and can produce oval buffers.

To workaround this use the AdvancedArcMapSettings utility to change the default projection used when buffering.

1. Close all ArcGIS applications.
2. In Windows Explorer, navigate to the \ARCGIS\ARCEXE8x\UTILITIES directory and double-click the AdvancedArcMapSetting.exe executable.
3. Click the Miscellaneous tab.
4. Change the 'Buffer processing coordinate system' option to either:
   "Coordinate system of the feature class (input)" or "Coordinate system of the feature class (output)"
5. Click Apply and close the dialog box.
6. Open ArcMap and perform the buffer.
7. Output buffer geometry can be improved further by projecting the ArcMap data frame or using ArcToolbox to project the data to an Equidistant

Shapefiles produced by the GeoProcessing Wizard in ArcMap do not have length or area attributes calculated for the new shapes. If the input shapes have these attributes, the output will inherit the existing values of these attributes.

This is a known issue with the GeoProcessing Wizard. The shapefile data structure does not support the automatic calculation of spatial attributes, such as area and length. The problem is that these attributes could be in any field, and the wizard could end up overwriting something that you do not want changed.

There are two work-arounds for this problem.

• Output the geoprocessing results to a geodatabase feature class. The Shape_area and Shape_length fields are correctly calculated.
• Recalculate the shapefile area and length field values. An example of how to do this is provided in the ArcGIS Desktop Help. On the Index tab type "tables" and double-click 'calculating field values'.

When creating buffers, the ArcMap Buffer wizard uses a temporary spatial reference system called the Buffer Processing Coordinate System, or BPCS. The wizard provides four options to change how this coordinate system is determined. For instructions on how to change this setting, see Related Information below.

• Feature set optimized - The BPCS is based on the the spatial distribution of the buffered features. A Hotine Oblique Cylindrical projection is used. Once created, the buffers are reprojected and saved in the coordinate system of the data frame. This is the default option for ArcMap.

• Feature optimized - A BPCS is created for each feature being buffered, and each is based on an equidistant azimuthal projection. Once created, the buffers are reprojected and saved in the coordinate system of the data frame.

• The Coordinate System of the data frame (output) - The BPCS is based on the coordinate system of the data frame. This method produces uniform buffers and without distortion.

• The Coordinate System of the Feature Class (input) - The BPCS is based on the coordinate system of the features being buffered. Once created, the buffers are reprojected and saved in the coordinate system of the data frame.

Sometimes the ArcMap Buffer Wizard will not create output for all of the features being buffered.
There are a few possibilities that may be inhibiting the creation of buffers:

A. The features being buffered are in a single data frame and are spread out across the entire world. There is a known limit buffering features at this scale.

B. The geometric complexity of the buffers being constructed are such that non-simple shapes are the result.

C. The features being buffered are multipart polygons or multipart features using attribute values as buffer distances.

Workaround
A. To buffer at a world scale.

1. Select a subset of the features.
2. Buffer the subset; save as a feature class.
3. Switch the selection.
4. Buffer the rest of the features; save as a feature classes.
5. Using the GeoProcessing Wizard, Merge the two buffer results into a new shapefile.

B. If not buffering at a world scale, enforce a simplification procedure during the buffering process.

1. Start the ArcMap Advanced Settings utility.
2. Check the Force geometric simplification during buffer processing checkbox.
3. Click Apply.
Forcing Simplification will slow down the buffering process.

C. If you are buffering multipart features you may need to create a new feature layer in which all the polygons are single features

The Geoprocesing Wizard is a tool found in ArcMap 8.x that provides the ability to Dissolve, Merge, Clip, Union and Intersect two layers. This tool is no longer available in ArcMap 9.0. The Geoprocessing Wizard has been replaced by individual tools located in ArcToolbox.

The new locations of these tools in ArcToolbox are:

Dissolve: Data Management toolbox > Generalization > Dissolve
Merge: Data Management toolbox > General > Append
Clip: Analysis toolbox > Extract > Clip
Intersect: Analysis toolbox > Overlay > Intersect
Union: Analysis toolbox > Overlay > Union