基于误差分析的岩芯高光谱数据几何校正方法

Geometric correction method of core hyperspectral data based on error analysis

南京地质调查中心研制的推扫式岩芯成像光谱仪由可见近红外成像光谱仪、短波红外成像光谱仪以及载有岩芯盘的导轨构成。导轨匀速运动的控制误差、两台独立成像光谱仪不同的空间分辨率不同以及不重合的视场范围,导致所获得的数据存在几何畸变,无法直接进行应用处理。针对上述问题,在分析了畸变产生机理的基础上,提出了基于三角形靶标的拉伸压缩畸变校正方法以及像元级与亚像元级联合配准方法。通过在岩芯盘一侧布设等腰直角三角形靶标,实现无位置姿态参数下的几何拉伸压缩畸变检测与校正;同时将尺度不便特征变化与扩展的相位相关方法相结合进行图像配准,提高图像配准的精度。实验结果表明,利用南京地质调查中心研制的岩芯成像光谱仪的实测高光谱数据进行方法性能验证,经过几何校正处理后的岩芯高光谱数据,拉伸压缩畸变校正精度为0.28个像元,配准精度优于0.1个像元。

The core imaging spectrometer developed by Nanjing Center of China Geological Survey consisted of a visible near infrared（VNIR） imaging spectrometer, a short wave infrared（SWIR） imaging spectrometer and a guide railway on which the core plate was mounted. The control accuracy of the uniform-speed moving guide railway and the different spatial resolutions and fields of view（FOV） of the VNIR imaging spectrometer and the SWIR imaging spectrometer caused geometric distortions on the core data. So the data obtained cannot be directly used for subsequent applications. In the face of thesepotential problems, on the basis of analysis error mechanism, geometric correction method based on the triangle calibration and joint image registration method of pixel and sub-pixel level were proposed. By setting triangle calibration target on one side of a core plate, geometric stretch and compression distortion was detected and corrected. By introducing scale invariant feature transform and extensible phase correlation, registration accuracy was improved. Experimental results using core hyperspectral data produced by Nanjing Center of China Geological Survey show that this improved geometric correction method can achieve a stretch and compression correction accuracy of 0.28 pixel and registration accuracy better than 0.1 pixel.