基于等效成像模型的立体测绘相机成像信噪比分析

Imaging SNR analysis of stereo mapping camera based on equivalent imaging model

为了评价立体测绘相机的成像质量和辐射性能,对相机成像信噪比特性进行了研究。通过对成像电路信号转换过程及各种噪声影响进行分析,建立了相机成像电路等效成像模型;根据立体测绘相机成像电路的工作状态对成像电路的输出信号、增益及各种噪声进行分析;利用相机的工程参数对立体测绘相机成像信噪比进行了分析计算;并对立体测绘相机进行实验室辐射定标测试。计算结果表明相机在4.33 W.m-2.sr-1、12.47 W.m-2.sr-1和40.41 W.m-2.sr-1这3种辐亮度条件下相机成像信噪比分别达到68倍、134倍和245倍。计算结果与实验结果最大相差4.4%,小于实验室绝对辐射定标精度7%。分析结果表明成像电路等效输出模型和成像信噪比计算方法是完全正确的,可以应用于立体测绘相机成像质量评价。

In order to evaluate the imaging quality and radiometric performance of stereo mapping camera,the imaging signal-to-noise ratio（SNR） of the camera was researched.An equivalent imaging model of the imaging circuit of stereo mapping camera was established through analyzing the photoelectric conversion process and effects of all kinds of noises.The output signal,imaging gain and all kinds of noises of the imaging circuit were analyzed according to the working status of the imaging circuit of stereo mapping camera.The imaging SNR of stereo mapping camera was calculated using the engineering parameters of the camera.The absolute radiation calibration test of the camera was carried out in the laboratory.Calculation results show that the imaging SNR of stereo mapping camera reaches 68,134 and 245 under the radiation conditions of 4.33 W·m-2·sr-1,12.47 W·m-2·sr-1 and 40.41 W·m-2·sr-1,respectively.The maximal error between the experiment result and calculation result is 4.4%,which is less than the radiation calibration test error of 7% in the laboratory.Analysis results prove that both the equivalent output model of the imaging circuit and the calculation method of imaging SNR are correct,which can be applied in the imaging quality evaluation of stereo mapping camera.