Frequently asked question

Why do SHAPE_Length and SHAPE_Area values differ between Pairwise Buffer and Create Buffers in ArcGIS Pro?

Last Published: October 7, 2024

Answer

Overview of the buffer tools in ArcGIS Pro

Buffer tools in ArcGIS Pro are used in spatial analysis, allowing users to create buffer zones around features such as points, lines, or polygons. The two main buffer tools used for this purpose are Pairwise Buffer and Create Buffers. While both tools are designed to generate buffer zones, they differ in how they process and store geometries, leading to small but noticeable variations in the calculated SHAPE_Length and SHAPE_Area values.

Differences in the SHAPE_Length and SHAPE_Area values between the tools

When both tools are used with the planar method, the SHAPE_Length and SHAPE_Area values are expected to be similar, but slight differences can be observed. These differences arise because the Pairwise Buffer tool uses a simplified geometry to represent the buffer, while the Create Buffers tool produces a more detailed, densified shape. Even though these variations seem minor, they can have significant implications in projects requiring precise geospatial data, such as in engineering, land-use planning, or any analysis that requires high accuracy.

The image below shows the difference between the SHAPE_Length and SHAPE_Area values of the Pairwise Buffer and Create Buffers tools.

The differences of values between the tools in the attribute table.

Characteristics of the Pairwise Buffer and Create Buffers tools

The Pairwise Buffer tool generates smoother buffer geometries by default, resulting in shapes that often resemble a perfect circle with a single vertex starting and ending at the top, as shown in the image below. This simplification leads to fewer vertices in the buffer geometry, which affects the resulting SHAPE_Length and SHAPE_Area values compared to those produced by the Create Buffers tool.

The vertex coordinate of the generated Pairwise buffer.

In contrast, the Create Buffers tool produces more detailed and densified geometries. The curves in the buffer are represented by many small line segments, as shown in the image below, creating a more complex and intricate shape. This additional detail can lead to small variations in SHAPE_Length and SHAPE_Area values, as the geometry generated by the Create Buffers tool is less smooth than that produced by the Pairwise Buffer tool.

The vertices coordinates of the generated Create buffer.

Selecting the right tool for specific tasks

The Pairwise Buffer tool is suitable when performance is a priority and slight variations in area or perimeter are acceptable. This makes it ideal for large datasets or for cases where the smoothness of the buffer is more important than geometric accuracy, such as environmental assessments. Conversely, the Create Buffers tool is better suited for tasks requiring high geometric accuracy, such as urban planning or precise land-use studies, where the extra detail in the buffer shape is critical.

Article ID: 000033596

Software:
  • ArcGIS Pro 3 1
  • ArcGIS Pro 3 3
  • ArcGIS Pro 3 2

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