bp_buffer_point

Geometric functions > bp_buffer_point

syntax

• bp_buffer_point(point_data_item, buffer_distance, nrPointsInCircle)

description

bp_buffer_point(point_data_item, buffer_distance, nrPointsInCircle) creates a circular buffer polygon around each point in the point_data_item. The result is a polygon data item with the same domain as the point_data_item.

The buffer_distance is a value that specifies the radius of the buffer circles in the units of the coordinate system.

The nrPointsInCircle is a UInt8 value that specifies the number of points used to approximate each circle. A higher value results in a smoother buffer but increases computation time. The minimum value is 3.

The bp_ prefix of the function name indicates that the implementation of the operator uses the Boost Polygon library, which requires integer coordinates.

applies to

• attribute point_data_item with a point value type with integer coordinates (ipoint or spoint)
• parameter buffer_distance with an integer value type
• parameter nrPointsInCircle with a UInt8 value type

conditions

1. The data item must have a point value type with integer coordinates (ipoint or spoint).
2. buffer_distance must be a positive value.
3. nrPointsInCircle must be at least 3.

This function results in problems for (integer) coordinates larger than 2^25 (after translation where the first point is moved to (0, 0)). If your integer coordinates, for instance, represent mm, 2^25[mm] = about 33 [km]. We advise you to keep the size of your integer coordinates limited.

since version

15.7.3

example

attribute<ipoint> point_buffer_circles (poly, pointset) := bp_buffer_point(pointset/geometry, 10i, 16b);

more examples of buffer functions can be found here: Buffer processing example

see also

• bp_buffer_linestring
• bp_buffer_multi_point
• geos_buffer_point
• bg_buffer_point
• cgal_buffer_point