Precision measurement of blade wall thickness along the common normal of inner and exterior surfaces is required to guarantee the reliability of air engine.
为保障航空发动机的可靠性，要求精确测量发动机叶片不同界面处的内、外表面法线方向的厚度。
2
The strong interrelationship among exterior elements of linear pushbroom imagery induces normal equation severely ill-posed and least squares value deviated from the true value.