Python与MapNik 等高线渲染&抽稀

7.1. Mapnik概述

导出的图像不包含坐标信息吗？在.xml文件

Mapnik核心是用C++写的，但是通过Python Bindings也可以调用，通过编写Python脚本来实现应用

>>参考：基于mapnik做切片服务器的几点总结：https://www.cnblogs.com/naaoveGIS/p/10719879.html

7.1.1. Mapnik制图快速开始

>>> import mapnik
>>> m = mapnik.Map(400,200,"+proj=latlong +datum=WGS84")
>>> m.background = mapnik.Color('steelblue')
>>> mapnik.render_to_file(m,'xworld.png', 'png')
>>> from IPython.display import Image
>>> Image('xworld.png')

7.1.2. 创建样式

>>> s = mapnik.Style()
>>> r=mapnik.Rule()
>>> polygon_symbolizer = mapnik.PolygonSymbolizer()
>>> polygon_symbolizer.stroke = mapnik.Color('#0f0f0f')
>>> r.symbols.append(polygon_symbolizer)
>>> line_symbolizer = mapnik.LineSymbolizer()
>>> # line_symbolizer.stroke = mapnik.Color('rgb(50%,50%,50%)')
>>> r.symbols.append(line_symbolizer)
>>> s.rules.append(r)
>>> m.append_style('My Style',s)