geoskill-vector-simplification

用 Douglas-Peucker / Visvalingam 算法简化矢量几何，统计顶点减少与面积保持。Simplify vector geometries with Douglas-Peucker / Visvalingam and report vertex reduction and area retention.

矢量简化 | Vector Simplification

Reduces the number of vertices in vector geometries with two classic line simplification algorithms, for small-scale cartographic generalization, data volume reduction and lower tile rendering load:

• Douglas-Peucker: iterative implementation that compares the perpendicular distance of points to the chord against a tolerance epsilon and removes points within the tolerance band; good shape preservation and the most widely used line/area simplification algorithm.
• Visvalingam-Whyatt: iteratively removes the point with the smallest "effective area" (the triangle area of three adjacent points) and supports stopping by an area threshold; smoother for jagged lines.

LineString / Polygon (with holes) / Multi* / GeometryCollection geometries are simplified recursively; simplified rings are guaranteed to remain closed with no fewer than 3 points. Reports the vertex reduction ratio and the polygon area retention rate. --synthetic mode generates a high-density circle (64 vertices) and a jagged line as test features.

Dependencies / 依赖

bash

pip install numpy rasterio geopandas shapely fiona pyproj

Usage / 使用方法

Basic Usage

bash

python geoskill-vector-simplification.py --bbox 116.0 39.0 117.0 40.0 --synthetic --output-dir ./out

示例 1（合成数据，Douglas-Peucker，离线）

bash

python geoskill-vector-simplification.py --bbox 116.0 39.0 117.0 40.0 --synthetic --method douglas-peucker --tolerance 0.001 --output-dir ./dp

示例 2：简化道路 Shapefile

bash

python geoskill-vector-simplification.py --input roads.shp --method douglas-peucker --tolerance 0.0005 --output-dir ./roads_simp

示例 3：Visvalingam 面积阈值简化边界

bash

python geoskill-vector-simplification.py --input boundary.gpkg --method visvalingam --tolerance 0.00001 --output-dir ./visv

示例 4：合成数据 Visvalingam

bash

python geoskill-vector-simplification.py --bbox 116.0 39.0 117.0 40.0 --synthetic --method visvalingam --tolerance 0.0001 --output-dir ./visv2 --quiet

Example 5: Large-Tolerance Quick Overview

bash

python geoskill-vector-simplification.py --input coast.geojson --method douglas-peucker --tolerance 0.01 --output-dir ./coarse

Output / 输出

File	Format	Description
simplified.geojson	GeoJSON	Simplified features
simplification_stats.json	JSON	Vertex reduction ratio, area retention rate
output-manifest.json	JSON	Run manifest

Data Source / 数据源 / Source

• --input: local vector file
• --synthetic: locally generated high-density test features

Privacy / 隐私声明 / Privacy

• Runs offline by default; --synthetic mode requires no network at all.
• All processing is done locally; user data is never uploaded.

License / License

MIT

---

---

name: geoskill-vector-simplification description: '用 Douglas-Peucker / Visvalingam 算法简化矢量几何，统计顶点减少与面积保持。Simplify vector geometries with Douglas-Peucker / Visvalingam and report vertex reduction and area retention.'

矢量简化 | Vector Simplification

用两种经典线简化算法减少矢量几何顶点数，用于小比例尺制图综合、降低 数据量与瓦片渲染负载：

• Douglas-Peucker：迭代版实现，比较点到弦的垂直距离与容差 epsilon， 删除容差带内的点，保形性好，是最常用的线/面简化算法。
• Visvalingam-Whyatt：迭代删除“有效面积”（相邻三点三角形面积）最小 的点，支持按面积阈值停止；对锯齿状线更平滑。

对 LineString / Polygon（含孔）/ Multi* / GeometryCollection 递归简化， 环简化后保证闭合且不少于 3 点。统计顶点减少比例与多边形面积保持率。 --synthetic 模式生成高密度圆（64 顶点）与锯齿线作为测试要素。

依赖

bash

pip install numpy rasterio geopandas shapely fiona pyproj

使用方法

基本用法

bash

python geoskill-vector-simplification.py --bbox 116.0 39.0 117.0 40.0 --synthetic --output-dir ./out

示例 1（合成数据，Douglas-Peucker，离线）

bash

python geoskill-vector-simplification.py --bbox 116.0 39.0 117.0 40.0 --synthetic --method douglas-peucker --tolerance 0.001 --output-dir ./dp

示例 2：简化道路 Shapefile

bash

python geoskill-vector-simplification.py --input roads.shp --method douglas-peucker --tolerance 0.0005 --output-dir ./roads_simp

示例 3：Visvalingam 面积阈值简化边界

bash

python geoskill-vector-simplification.py --input boundary.gpkg --method visvalingam --tolerance 0.00001 --output-dir ./visv

示例 4：合成数据 Visvalingam

bash

python geoskill-vector-simplification.py --bbox 116.0 39.0 117.0 40.0 --synthetic --method visvalingam --tolerance 0.0001 --output-dir ./visv2 --quiet

示例 5：大容差快速概览

bash

python geoskill-vector-simplification.py --input coast.geojson --method douglas-peucker --tolerance 0.01 --output-dir ./coarse

输出

文件	格式	说明
simplified.geojson	GeoJSON	简化后的要素
simplification_stats.json	JSON	顶点减少比例、面积保持率
output-manifest.json	JSON	运行清单

数据源 / Source

• --input：本地矢量文件
• --synthetic：本地生成高密度测试要素

隐私声明 / Privacy

• 默认离线运行，--synthetic 模式完全无网络。
• 所有处理在本地完成，不上传用户数据。

License

MIT