GFE Configuration Item	Applicable to GFE	Applicable to ifpIMAGE	Notes
Significant Weather Time-Weighted Sample Threshold	YES	NO
Default Pencil Width	YES	NO
Pencil Influence Sizes	YES	NO
Interpolation Algorithm	YES	NO
Smoothing Algorithm	YES	NO
Contour Sub Sample	YES	NO

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Significant weather time weighted average percent

Smart tools can request a time-weighted average of grids.  For weather, this requires a threshold.  The weather key returned from the time-weighted average of grids, includes all weather sub keys that exist for more than the Significant WeatherTimeWeightAverage_percent of the grids.  If none of the sub keys exceed the threshold, then the most dominent subkeys) will be used as the time-weighted average.

For example, let's say there are three weather grids, the first is an hour long, the second is two hours long, and the third is three hours long.  There is Rain in the first grid, Snow in the second grid, and Thunder and Rain in the third grid.  The total duration of the three grids is 6 hours. The percentages calculated via this algorithm is shown in the following table:

Weather Type	First Grid	Second Grid	Third Grid	Total Duration	Percentage
Rain	1 hour	0 hours	3 hours	4 hours	66.6%
Snow	0 hours	2 hours	0 hours	2 hours	33.3%
Thunder	0 hours	0 hours	3 hours	3 hours	50.0%

 

Depending upon the threshold, the time-weighted results can be different, as shown in the following table:

Threshold	Result	Notes
20%	Rain, Snow, Thunder	all of the weather types are above the threshold
40%	Rain, Thunder	Snow is only 33.3%, so it is not part of the time-weighted average
60%	Rain	Only rain is above the threshold.
80%	Rain	Since none of the entries are above the threshold, the result is the subkey that is most predominent.

 
SignificantWeatherTimeWeightAverage_percent = 40
 

Default Pencil Width

The default pencil width is specified per weather element in grid cells.  The pencil width can be changed interactively through the GFE GUI.  If not specified, the default is set to 5 grid cells. For those weather elements that are not-surface based, the format is parmName_level_pencilWidth.

T_pencilWidth = 5
 

Pencil Influence Sizes

The number and value of the Pencil Tool's Influence Sizes can be defined in the GFE config file as well.  Just define a list of sizes in grid cells much like the Pencil Tool Width.

PencilToolInfluence_list = [2, 4, 8, 12, 16]

You are allowed to enter as many sizes as you want, but be warned.  The resulting menu may be too long to be completely displayed on the screen.

Interpolation Algorithm

The interpolation algorithm may be specified for each weather element.  The format of the entry is parmName_interpolateAlgorithm.  If not specified, then the format defaults to that shown in the following table:

Weather Element	Default Algorithm
QPF	CUBIC_ADVECT
Sky	CUBIC_ADVECT
PoP	CUBIC_ADVECT
all others	CUBIC_NOADVECT

The available algorithms are shown in the following table:

Algorithm	Description
CUBIC_ADVECT	Cubic spline is applied to the data points temporally.  Software looks for areas that can be advected.  The advection component of the algorithm works best for weather elements that contain areas of zero value.
CUBIC_NOADVECT	Cubic spline is applied to the data points temporally.  Software gradually adjusts points from starting value to ending value without advection considerations.
LINEAR_ADVECT	Linear calculations are applied to adjacent base grids temporally.  Software looks for areas that can be advected.  The advection component of the algorithm works best for weather elements that contain areas of zero value.
LINEAR_NOADVECT	Linear calculations are applied to adjacent base grids temporally.  Software gradually adjusts points from starting value to ending value without advection considerations.

 
An example of setting Temperature to use the linear and advective capabilities of the interpolation, you would do the following:

T_interpolateAlgorithm = "LINEAR_ADVECT"

For those weather elements that are not surface based, the format is parmName_level_interpolateAlgorithm.
 

Smoothing Algorithm

The Smoothing Algorithm can use a number of possible smoothing filters.  By default, the choices are 3x3, 5x5, 7x7, or 9x9.  Generally, more smoothing will occur with larger smoothing filter sizes. When the GFE is first started, the 3x3 filter size is the default, but this can be changed to any one of the filter sizes in the list.  To change the default add this line to your GFEConfig file.

SmoothSize = 7

In this example the smoothing filter size will default to 7x7, when the GFE is started.

The list of possible filter sizes can be configured in the GFE as well.  To define a new list, which appears in the main menu item GFE->Editing Preferences, use the following syntax in your GFEConfig file.

SmoothSizeList = [3, 5, 7, 9, 11]

Note that all of the integer values are odd.  Even values will give the same results.  For example, a value of 2 will give the same results as 3, 4 the same as 5, and so on.  We recommend that you define the list with odd values simply for consistency.
 

Contour Sub Sample

The Countour Analyzer algorithm is used to convert contours into a grid for the Contour Tool.  It can run over a subsampled grid to improve performance.  This is usually ok since the contour tool is mostly used where there is not much detail due to topography. The value of ContourSubSample is used to divide the x and y dimensions of the original grid to get the dimensions of the subsampled grid. So, setting ContourSubSample to 4 would cause the Contour Analyzer to reduce a 400x400 grid to a 100x100 grid for contouring purposes. This can greatly speed up the algorithm.  Setting ContourSubSample to 1 will cause no reduction. The default value is 4.  If ContourSubSample is set to a value less than or equal to 0 then it will go back to 4.  If it is set to a value large enough to make the subsampled grid have an x or y dimension less than 5, then it will be reduced so that the minimum dimension for x or y will be 5.  This configurable item is simply for performance.

ContourSubSample = 4

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