principal plane principal vertical plane
摄影测量与遥感学英语词汇(2) ... 象主纵线principalline[ofphotograph] 主垂面principalplane[ofphotograph],principalverticalplane 真地平线truehorizon ...
prime vertical plane
... 主尺 pnmary divisions 主垂面 prime vertical plane 主导线纲 principal polygonometric network ...
主垂面