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Table 1 Comparison of Zernike moment between the original and rotated images in two coordinates system

From: A new method based on stacked auto-encoders to identify abnormal weather radar echo images

Image feature Original image Rotation angle (°)
30 45 60 90
Value in log-polar coordinate system
 Zernike moment 1,775,000 1,543,900 1,563,000 1,578,700 1,325,600
 Normalized value 1 0.87 0.88 0.89 0.75
 Difference value   0.13 − 0.01 − 0.01 0.14
Value in Cartesian coordinate system
 Zernike moment 5,257,300 3,423,600 3,188,100 3,748,300 3,298,300
 Normalized value 1 0.65 0.61 0.71 0.63
 Difference value   0.35 0.04 − 0.11 0.09