从简单Convolution shadow map shadow map到各种改进
方差阴影图 https://blog.youkuaiyun.com/toughbro/article/details/6091152
指数阴影图 Exponential Shadow Maps http://www.trentreed.net/blog/exponential-shadow-maps/
http://www.docin.com/p-1003716456.html
阴影图技术汇总:https://lengbingteng.iteye.com/blog/1846909
阴影图汇总及比对:https://developer.download.nvidia.cn/presentations/2008/GDC/GDC08_SoftShadowMapping.pdf
https://software.intel.com/en-us/articles/comparing-shadow-mapping-techniques-with-shadow-explorer/
改进的ESM http://www.klayge.org/2013/10/07/%E5%88%87%E6%8D%A2%E5%88%B0esm/
分层阴影贴图 http://www.zwqxin.com/archives/opengl/shadow-map-4.html
阴影图技术汇总:https://graphics.stanford.edu/~mdfisher/Shadows.html
方差阴影贴图:https://wenku.baidu.com/view/6d9ffef1f61fb7360b4c6558.html
解释log space filter:http://advances.realtimerendering.com/s2009/SIGGRAPH%202009%20-%20Lighting%20Research%20at%20Bungie.pdf