说明：  此文档是我学习OSG做的技术总结报告，详细讲解了OSG、OSGearth的编译，开发，osg原理，视点变换矩阵、全球地形解决方案等。
(This document is do I learn OSG technical summary report, a detailed account of OSG, compiled OSGearth, development, osg principle viewpoint transformation matrix, the global terrain solutions.)