🗺️ Buffer (Radius) Analysis

Generate buffer zones around points, lines or polygons by a given radius and analyze the covered area.

📐 计算公式

点缓冲面积 = πr²；线缓冲面积（胶囊形）= 2rL + πr²；缓冲周长 = 2πr + 2L；线长为 0 时线缓冲退化为点缓冲

点缓冲面积=π×半径²；线缓冲（胶囊形）面积=2×半径×线长+π×半径²；缓冲周长=2×π×半径+2×线长。线长填 0 时仅计算点缓冲。

缓冲半径 r（米）

线状要素长度 L（米，点缓冲填 0）

📚 深度解析：缓冲区（半径）面积与周长分析

示例：道路两侧缓冲

缓冲半径 30 m、线长 100 m：点缓冲面积≈π×30²≈2827 ㎡；线缓冲（胶囊形）面积＝2×30×100＋π×30²≈8827 ㎡；缓冲周长＝2×π×30＋2×100≈389 m。线长填 0 时只算点缓冲。

线缓冲面积为什么比点缓冲多出 2×半径×线长？: 线缓冲是沿线段两侧各外扩半径形成的矩形（面积 2rL）加两端半圆（合起来一个圆 πr²），合计 2rL＋πr²；点缓冲只是 πr²。
周长怎么算？: 胶囊形周长＝两条长边 2L 加两端整圆周长 2πr，即 2L＋2πr；半径越大或线越长，覆盖边界越长。

Item	Formula / Note	Source / Standard
Buffer area of a point feature	A = pi · r^2, where r is the buffer radius	ISO 19107:2003, Geographic information - Spatial schema
Buffer area of a line feature	A = 2 · r · L + pi · r^2, where L is the line length	ISO 19107:2003, Geographic information - Spatial schema
Definition of a buffer	A polygon neighbourhood within a given distance of the source feature	ISO 19125-1:2004, Geographic information - Simple feature access - Part 1
Effect of the radius	Buffer area grows with the square of the radius; doubling r roughly quadruples the area	ISO 19107:2003, Geographic information - Spatial schema

⚠️ 使用说明与注意事项