avfilt3 [ parameter=value ... ] [ inputfile ... ]
Parameters are box_lines, box_samples, min_good_vals.
avfilt3 is a simple moving average low pass filter used to reduce the noise in AVHRR channel 3. This function can be applied to either the raw count data or the calibrated data.
A more elaborate routine that uses similarities between channels 3 and 4 to isolate the noise and determine its spectra has not been implemented because it is extremely sensitive to discontinuities in the data such as boundaries between cloud and water or water and land.
One or more input TeraScan datasets are required for input. This function operates on datasets in place; therefore, no output data sets are required.
This parameter specifies the number of lines (e.g. height) of the moving average box.
The valid range is [1 to 25]. The default is 3.
This parameter specifies the number of samples (e.g. width) of the moving average box.
The valid range is [1 to 25]. The default is box_lines.
This is the minimum number of valid data points within the moving box required to compute a weighted average. If there are not enough valid data points, the center point of the box is assigned the bad value.
The valid range is [1 to box_lines*box_samples]. The default is box_lines.
Reduce the noise in AVHRR channel 3 of pass1.
% avfilt3 input file(s) : char(255) ? pass1.dat box_lines : int ? [3] 10 box_samples : int ? [10] 10 min_good_vals : int ? [10]
avhrr, avin, avcal, nitpix, avfix
Last Update: $Date: 1998/05/28 19:46:11 $