192 lines
11 KiB
HTML
192 lines
11 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<html>
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<head>
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<meta http-equiv="CONTENT-TYPE" content="text/html; charset=utf-8">
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<title>Adjust</title>
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<meta name="GENERATOR" content="OpenOffice.org 1.1.3 (Linux)">
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<meta name="CREATED" content="19951121;16410000">
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<meta name="CHANGED" content="20050706;13040400">
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<style>
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<!--
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@page { size: 8.5in 11in; margin-right: 1.25in; margin-top: 1in; margin-bottom: 1in }
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P { margin-bottom: 0.08in; direction: ltr; color: #000000; text-align: left; widows: 0; orphans: 0 }
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P.western { font-family: "Bitstream Vera Serif", "Times New Roman", serif; font-size: 12pt; so-language: en-US }
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P.cjk { font-family: "Bitstream Vera Sans"; font-size: 12pt; so-language: }
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P.ctl { font-family: "Lucidasans"; font-size: 12pt; so-language: }
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-->
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</style>
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</head>
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<body dir="ltr" lang="de-DE" text="#000000">
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<font face="New Century Schoolbook, Times New Roman, serif"><font
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size="5"><b>Adjust</b></font></font>
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<br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif"><font
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size="3"><b>Introduction</b></font></font>
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<br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">Adjust is a GFE SmartTool
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that performs basic math functions like add, subtract, multiply and divide on a grid.
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However, as is often useful with GFE, it allows options related to elevation (i.e.,
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adding mostly at higher elevations, or subtracting mostly at lower elevations), and
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related to edit areas (i.e., adding most in the center of the edit area, or adding
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nearly the same amount everywhere – but ‘ramping down’ to no change at the edge of
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the edit area). You can combine these options in a variety of ways. This tool
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really takes the place of many other tools previously on the SmartTool Repository
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like UpMtn and DownValley, but it also provides many more combinations due to the
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ability to specify the edge effect and elevation effect options ‘on-the-fly’.</font>
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<br>
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<br>
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<br>
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<big><big><font style="font-weight: bold;"
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face="New Century Schoolbook, Times New Roman, serif">How
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the Procedure Works</font><span style="font-weight: bold;">
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</span></big></big><br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">The basic function of the tool
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is to take the specified value and perform the specified action of Add, Subtract, Multiply
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or Divide:<br><br>
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<img alt="Adjust" src="images/Adjust.jpg"></font>
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<br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">The value can be any number,
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either an integer or floating-point number, and can be negative (multiplying by negative
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one is especially useful for changing the sign of a grid). The final grid values,
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however, will not be allowed to lie outside the range of valid values for that particular
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grid parameter. Dividing by zero is, of course, not allowed.
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<br><br>
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Adding and Subtracting is useful for most parameters, such as adding or subtracting a
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few degrees from temperatures, or adding or subtracting a few percent from PoPs.
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Multiply and Divide are most useful with certain parameters, such as increasing QPF
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by multiplying by 1.5, or dividing by 2 to cut PoPs in half.</font>
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<br>
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<br>
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<br>
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<big><big><font face="New Century Schoolbook, Times New Roman, serif"><b>Vector Option</b></font>
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</big></big><br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">For vector parameters, the
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setting of the GFE Vector Editing Mode is ignored, but instead is controlled by the
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vector setting on the tool itself (see graphic above).
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<br><br>
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If the vector setting is “Both” and the value is set to 10.0, then performing an
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Addition operation will add 10 knots to the magnitude of a wind, and add 10 degrees
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to the direction (veer the wind by 10 degrees). This is only rarely what you want,
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so the Both option is rarely used. More typically you only operate on the vector
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Magnitude, and that is why it is selected by default when you start the tool.</font>
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<br>
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<br>
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<br>
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<big><big><font face="New Century Schoolbook, Times New Roman, serif"><b>Edge Option</b></font>
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</big></big><br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">The tool works either on an
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edit area or the entire grid. When working on an edit area, the edge options can be
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useful to “blend” your changes into the rest of the grid.
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<br><br>
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The Flat option, makes no attempt to “blend” your changes into the edges of your edit
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area. For example, if you start with a constant grid of 1 (let’s say it is a PoP grid)
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and define an edit area.<br>
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<img alt="Adjust" src="images/Adjust1.png"><br><br>
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If you then add a value of 50, with an edge option of flat, you will get:<br>
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<img alt="Adjust" src="images/Adjust2.png"><br><br>
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Note that inside the edit areas, the value is now 51 (50 + 1), and there has been no
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attempt to “blend” these values into the rest of the grid. If, however, the edge option
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is chosen then the result would be:<br>
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<img alt="Adjust" src="images/Adjust3.png"><br><br>
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Note that most of the edit area still contains the value of 51 (50+1), but near the
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edges of the edit area, the adjustment is “scaled back” down to zero along the edge,
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so that it “blends in” with the rest of the grid. The width of the edge effect is
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controlled by the Edge Width slider which defaults to 5, meaning the values are
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blended in over 5 pixels, or gridboxes. If, however, the taper option is chosen
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then the result of adding 50 will be:<br>
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<img alt="Adjust" src="images/Adjust4.png"><br><br>
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Note that only one pixel, furthest from the edge of the edit area, receives the full
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adjustment of adding 50 and reaching a final value of 51. Everywhere else receives
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a lesser amount of adjustment such that the value blends in across the entire edit area.
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<br><br>
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Note, however, that the taper function has an error if the edit area includes the edge
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of the GFE grid. In this example, the grid includes the corner of the GFE grid and
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the taper function produces an incorrect adjustment:<br>
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<img alt="Adjust" src="images/Adjust5.png"><br><br>
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It is worth pointing out that for addition and subtraction, the edge and taper options
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trend to “zero” or “no-change” at the edge of the edit area. However, for
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multiplication and division, the edge and taper options trend to “one” at the edge of
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the edit area, because multiplying or dividing by 1.0 gives the “no-change”
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effect.</font>
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<br>
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<br>
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<br>
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<big><big><font face="New Century Schoolbook, Times New Roman, serif"><b>Elevation Option</b></font>
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</big></big><br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">The elevation option
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allows you to perform your operation (add, subtract, multiply or divide) mostly
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in areas of similar elevation. If the None option (the default) is chosen, then
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elevation does not influence the operation.
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<br><br>
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However, if the Mountain option is chosen, then the full adjustment will take
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place at the highest elevation in the edit area, and zero adjustment will take
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place at the lowest elevation in the edit area. For example, with topography
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like this:<br>
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<img alt="Adjust" src="images/Adjust6.png"><br><br>
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The highest elevation is along the extreme right edge of the edit area.
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The lowest elevation is in the upper center of the edit area. The result
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of adding 50 to our constant grid of 1, gives:<br>
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<img alt="Adjust" src="images/Adjust7.png"><br><br>
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Note how only one pixel gets the final value of 51, and it is the point inside
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the edit area with the highest elevation. Likewise, if the Valley option is chosen
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Then the effect is just the opposite, the full adjustment is made at the lowest
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elevation inside the edit area, and zero adjustment is made at the highest
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elevation:<br>
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<img alt="Adjust" src="images/Adjust8.png"><br><br>
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If the Specific option is chosen Then the full adjustment will take place at the
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specific elevation. The effect will then taper down to zero adjustment at both
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the highest and lowest elevation inside the edit area:<br>
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<img alt="Adjust" src="images/Adjust9.png"><br><br>
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Note that if the elevation specified is above the highest elevation inside the
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edit area, then the effect will be exactly the same as choosing the “Mountain”
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option. Likewise, if the elevation specified is below the lowest elevation
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inside the edit area, then the effect will be exactly the same as choosing
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the “Valley” option.</font>
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<br>
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<br>
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<big><big><font face="New Century Schoolbook, Times New Roman, serif"><b>Combined
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Elevation and Edge Options</b></font>
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</big></big><br>
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<br>
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<font face="New Century Schoolbook, Times New Roman, serif">Any of the options
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can be combined. As the examples above show, when using the elevation options
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of Mountain, Valley, or Specific, there will likely be harsh gradients produced
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at the edge of the edit area. If, for example, the Edge option is also chosen
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along with the Mountain option, with an addition of 50, the result is:<br>
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<img alt="Adjust" src="images/Adjust10.png"><br><br>
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Note that the adjustment now blends in well with the rest of the grid, because
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the edge effect is trending the adjustment back toward zero at the edges of the
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edit area. However, also note that the adjustment is also putting most of the
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adjustment at the higher elevations. It is worth pointing out that, in this case,
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the gridbox that receives the full adjustment is not the gridbox with the highest
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elevation (because that point is also on the edge of the edit area).
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Instead, a point further inside the edit area, which has a high elevation,
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receives the full adjustment:<br>
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<img alt="Adjust" src="images/Adjust11.png"><br><br>
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Mathematically, the two adjustment function are simply multiplied together, and
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re-scaled, so that at least one gridbox receives the full adjustment.
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<br><br>
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Similarly, the combination of the Mountain option with the Taper option yields:<br>
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<img alt="Adjust" src="images/Adjust12.png"><br><br>
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Here, the taper option would like to put the most adjustment in the middle of the
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edit area, but the lowest elevations are also in that area, so the combination
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puts the maximum adjustment at a relatively high elevation, but as close to the
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center of the edit area as possible:<br>
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<img alt="Adjust" src="images/Adjust13.png"><br><br>
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Old tools on the SmartTool repository were hard-coded combinations of some of these
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options. For example, the UpMtn tool is essentially a combination of Add, Mountain
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and Edge, with an edge width of 5 gridboxes. The DownValley tool is essentially a
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combination of Subtract, Valley and Edge, with and edge width of 5 gridboxes.
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The MultiplyDivide tool provided a combination of Multiply, None, Flat as well as
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Divide, None, Flat options. Putting all these options into a single tool means
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fewer tools on the GFE tool list, and provide some new combinations.</font>
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</body>
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</html>
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