说明：  SpeedTree_植被引擎介绍---Speedtree是一款专门的三维树木建模软件，支持大片的树木的快速建立和渲染，而且它本身还带有强大的树木库，软件是由美国IDV公司研发制作的。
(SpeedTree_ Introduction--- Speedtree vegetation engine is a specialized three-dimensional modeling software trees, large trees to support the rapid creation and rendering, but also its own library with a powerful tree, the software is developed by the U.S. company produced IDV .)