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Data channel for trends
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The channel to find trends for. To specify an array element append to the channel array name the element index in square brackets. For example Chan[1] would indicate the second element of the array channel Chan.
Script Parameter: TRENDDB.ZCHAN
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Window for max-min search
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All maxima and minima found are guaranteed to be the lowest or highest values within half this distance on either side of selected point. The distance is determined from the X and Y channel positions, measured cumulatively from point to point. (Default = 100)
Script Parameter: TRENDDB.WINDOW
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Preferred angle for trends
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The angle is the angle measured counter-clockwise from the horizontal (X-axis) in degrees.
Script Parameter: TRENDDB.ANGLE
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Allowable deviation in angle
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This is the amount by which the trend angle of individual trend sections may deviate from the preferred angle. For instance, if the preferred angle were 30 degrees, an allowable deviation of 30 degrees would search for trends at angle from 0 to 60 degrees. (Default = 30)
Script Parameter: TRENDDB.DEVIATION
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Maximum length for joins
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It is usually good to set this to about twice the average line spacing. Too large a value may create trend lines across large "empty" regions, and can increase the processing time. The value should exceed the average line spacing, or no joining or extrema may occur. (Default = 500)
Script Parameter: TRENDDB.MAXLENGTH
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Maximum deflection for joins
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This controls the local "straightness" of joins. The deflection is the length of the perpendicular dropped from the third point in a sequence to the line which joins the first two points. If the three points are co-linear, this value will be zero. If the input value is left blank, no check will be made for this condition.
Script Parameter: TRENDDB.DEFLECTION
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Minimum length for the trend line
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Ignore all trend lines shorter than this. This test is applied after any resampling, and before breaking of lines at the breaking angle. If left blank, this test is not performed.
Script Parameter: TRENDDB.MINLENGTH
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Resampling Interval along trends
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The line may be splined at a fixed interval. For maximum effectiveness, this should be set to a value which is a fraction of the average line spacing; this could be the along-line sample interval. This will reinforce the data values along the trend lines. The start and end points are preserved. If left blank, this test is not performed.
Script Parameter: TRENDDB.RESAMPLE
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Trend line breaking angle
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Some routines such as BIGRID require that lines increase monotonically in certain directions. Because trend lines are often nearly parallel to the first spline direction in BIGRID, they can be multiple-valued functions. Forcing breaks when the line direction switches "back and forth" over the first spline direction restores the monotonic nature to the all the lines, and ensures the entire trend line is used. The first spline direction is set in BIGRID using the "Trend Angle" parameter. If it is left blank, this will be either 0 or 90 degrees, depending on the general flight line direction. Set the breaking angle to the Trend Angle for best results.
For example: If flight lines are mostly vertical, then the initial BIGRID interpolation will be along horizontal lines. To ensure trend lines will be fully used, set the break angle to 0 degrees.
If the break angle is left blank, this test is not performed, and some trend information may not be used.
Script Parameter: TRENDDB.BRANGLE
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