Modulation Transfer Function Measurement Method and Results for the Orbview-3 High Resolution Imaging Satellite

The Modulation Transfer Function (MTF) is a fundamental imaging system design specification and system quality metric often used in remote sensing. MTF is defined as the normalized magnitude of the Fourier Transform of the imaging system’s point spread function. Alternatively, the MTF describes the attenuation of sinusoidal waveforms as a function of spatial frequency. Practically, MTF is a metric quantifying the sharpness of the reconstructed image. On-orbit measurement techniques are discussed to quantify the along scan and cross scan MTF profiles. While many measurement techniques exist, the technique utilized is designed to provide accurate measurements for high resolution imaging systems. Additionally, a confidence interval is assigned to the measurement as a statement of the quality of the measured value. The classical slant-edge measurement technique for discrete sampled systems is employed. Fixed high-contrast targets are used to obtain MTF measurements in the center of the array. As access to such targets is limited, suitable edges for analysis are identified in nominal operational imagery. The measurement results from the specialized targets are used to confirm the large number of measurements from the operational imagery. The data sets used in the analysis are from the OrbView-3 (OV-3) High Resolution Imaging Satellite, launched June 26, 2003. Results are presented for the 1 meter ground sample distance (GSD) panchromatic band of the OV-3 system.