Suggestions for using the radiometric terrain and land cover corrections

If you know which filter type and size will produce the best results for your image, you can apply the filter at the same time as you orthorectify the image. Otherwise, you can use Nearest Neighbor resampling during orthorectification, and then filter and manipulate the orthorectified image afterwards to obtain the results you want. However, if in the Set Projection window the value of Output pixel spacing and Output line spacing (pixel size) differ from those of the input images, you must adjust the filter size so that it covers the same ground area.

For example, the pixel size is set to change from 6.25 meters to 12.5 meters during orthorectification. Using a five-by-five filter during the orthorectification would produce roughly the same results as if you instead applied a three-by-three filter to the orthorectified image.

To produce the sharpest output and preserve the speckle statistics

1. In the Set Projection window, in the Output pixel spacing and Output line spacing boxes, enter values that are as close to the pixel size of the input image as possible.
2. In the Ortho Image Production window, under Processing Options, type or select one (1) in the Sampling interval box, and then in the Resampling list, click Nearest.

Lower-resolution digital elevation model than input image

For land cover correction

Coefficient values between 0.5 and 1.0 produce the best results for most images. Using a coefficient value near 2.0 may produce an over-correction, which results in the facing slopes becoming too dark and the back slopes becoming too bright. Since the results depend on the sensor, the beam mode, and the image, finding the best result for your project will involve some experimentation.