1 生成6张图
https://blog.csdn.net/lin453701006/article/details/71173090
2
http://www.360doc.com/content/14/0512/18/17164701_377013140.shtml
Equirectangular Projection(ERP)
https://blog.csdn.net/lin453701006/article/details/71173090
http://www.360doc.com/content/14/0512/18/17164701_377013140.shtml