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Smoothing Point Data

Smoothing data is an efficient way to get more out of your yield, moisture and soil sample data. Smoothing displays an accurate picture of point-based layers through several different methods: Average, Average & Contour, Smooth, and Smooth & Contour. The different methods allow you to see patterns in your data more quickly, and decrease the amount of time required to display the layers. Use the Quick Reference Guide to determine which method might be appropriate in different situations.

Quick Reference
Average Method
Average & Contour Method
Smooth Method
Smooth & Contour Method
Smoothing over Defined Boundaries
Advanced Options Box
Smoothing Interpolation Method

Using the Average Method

The Average method of smoothing will give your map a gridded appearance: each grid square will be filled with the average of the data points within that grid. It is best to Average data when dealing with a large number of points within a small area, yield maps, for example. The Average method calculates all points within each grid square, add the data together, and divides by the number of points. Averaged views load faster than Base Data.

To smooth data using the Average Method:

1. Click on the Smoothing button found on the Layer Tools toolbar.

2. In the Smoothing box, select Average as the Method, and then select the Layer to smooth. This will default to the Active Layer.

3. If the layer has data for more than one field, select the Field to be averaged. Select <ALL> to average all data on the layer.

4. Next, enter the Grid Resolution, or size of grid, you wish to use. Note that this grid may be set to a custom or standard size.

5. Select the OK button and the cursor becomes a grid. Hold down the left-mouse button and drag the grid so that the map being smoothed falls within desired grids. When the mouse button is released, a new view of the layer will be created and displayed.

Using the Average and Contour Method

The Average & Contour method of smoothing will give your map a smoothed appearance that will show distinct areas of your fields that fall within certain ranges. This method is useful for yields and moisture since it works well with small areas that contain a large number of points. Displaying an Averaged and Contoured view is faster than displaying Base Data.

To smooth data using the Average & Contour Method:

1. Click on the Smoothing button found on the Layer Tools toolbar.

2. In the Smoothing box select Average & Contour as the Method, and then select the Layer to smooth. This will default to the Active Layer.

3. If the layer has data for more than one field, select the Field to be contoured. Select <ALL> to contour all data on the layer.

Note: Contouring will only affect a single data item on the layer: moisture, for example. The affected item will be displayed in the Data Item box.

4. Next, select Use Field boundaries or Use Points as boundaries. If fields are drawn on the Main Farming Layer, select Use Field and the contours will conform to the field boundaries. With Use Points selected, contours will not conform to the field boundaries.
   
   
   
   

5. Next, enter the Grid Resolution, or size of grid, you wish to use. Note that this grid may be set to a custom or standard size.

Note: Grid Resolution will default to a 100 Foot grid. This is a normal grid size for yield maps. This number can be changed as desired. Smaller grid resolutions will give your contours a smoother appearance. However, it will also increase the time required for creating the contours.

6. If desired, click on the Options button. In the Advanced Options box, enter a Minimum Area for the contours. When creating the contoured areas, Farm Site and Site Pro will ignore all contours less than this area and will combine them with adjoining contours. Select OK.

7. Select the OK button and the cursor becomes a grid. Hold down the left-mouse button and drag the grid so that the map being smoothed falls within desired grids. When the mouse button is released, a new view of the layer will be created and displayed.

Using the Smooth Method

Using the Smooth method will give your map a gridded appearance: each grid square will be filled with a weighted average for the data within and around that grid. Smoothing is useful for layers that have a small number of points in a large area, soil sample layers, for example. Displaying a Smoothed view is faster than displaying Base Data.

To smooth data using the Smooth Method:

1. Click on the Smoothing button found on the Layer Tools toolbar.

2. In the Smoothing box select Smooth as the Method, and then select the Layer to smooth. This defaults to the Active Layer.

3. Select the Field to be averaged. Select <ALL> to average all data on the layer. Next, select smooth points using the Field Boundaries based on the Main Farming Layer or Use Points. If fields are drawn on the Main Farming Layer, select Use Field and the grids will conform to the field boundaries. With Use Points selected, grids will not conform to the field boundaries.

Note: With Use Points, grid squares will only receive values if they have points within them. With Field Boundaries selected, the Smooth option uses points that go beyond the selected grid squares; every grid will have a value assigned to it, regardless of points in the area. Use Fields must have a Field selected to smooth.

4. Next, enter the Grid Resolution, or size of grid, you wish to use. Note that this grid may be set to a custom or standard size.

Note: Grid Resolution will default to a 100 Foot grid. This is a normal grid size for yield maps. This number can be changed as desired. Smaller grid resolutions will give your contours a smoother appearance. However, it will also increase the time required for creating the contours.

5. Smooth view grids are calculated on a weighted average based on distances. To change variables used in the calculations, select the Options button. The Advanced Options box defaults to the typical settings for yield maps with a 1-acre grid. The grid should be changed if working with data other than yield or if using a Grid Resolution other than 1 acre. For more information on the Interpolation Methods utilized, see Interpolation Method Used For Smooth and Smooth & Contour Methods. Click OK.

6. Select the OK button and the cursor becomes a grid. Hold down the left-mouse button and drag the grid so that the map being smoothed falls within desired grids. When the mouse button is released, a new view of the layer will be created and displayed.
   

Using the Smooth & Contour Method

The Smooth & Contour method of smoothing will give your map a smoothed appearance; each contour will be filled with a weighted average for the data within and around that contour. Smooth & Contour is useful for layers that have a small number of points in a large area: soil sample layers, for example. Displaying a Smooth & Contoured view is faster than displaying Base Data.

To smooth data using the Smooth & Contour Method:

1. Click on the Smoothing button found on the Layer Tools toolbar.

2. In the Smoothing box select Smooth & Contour as the Method, and then select the Layer to smooth. This defaults to the Active Layer.

3. If the layer has data for more than one field, select the Field to be contoured. Select <ALL> to contour all data on the layer. Next, select smooth points using the Field Boundaries based on the Main Farming Layer or Use Points. If fields are drawn on the Main Farming Layer, select Use Field and the contours will conform to the field boundaries. With Use Points selected, contours will not conform to the field boundaries.

Note: With Use Points, grid squares will only receive values if they have points within them. With Field Boundaries selected, the Smooth option uses points that go beyond the selected grid squares; every grid will have a value assigned to it, regardless of points in the area. Use Fields must have a Field selected to smooth.

4. Contouring will only affect a single data item on the layer. The affected item will be displayed in the Data Item box.

5. Next, enter the Grid Resolution, or size of grid, you wish to use. Note that this size can be entered as an area or height/width of each grid square.

Note: Grid Resolution will default to a 100 Foot grid. This is a normal grid size for yield maps. This number can be changed as desired. Smaller grid resolutions will give your contours a smoother appearance. However, it will also increase the time required for creating the contours.

Smooth view grids are calculated on a weighted average based on distances. To change variables used in the calculations, select the Options button.

The Advanced Options box defaults to the typical settings for yield maps with a 1-acre grid. The grid should be changed if working with data other than yield or if using a Grid Resolution other than 1 acre. For more information on the Interpolation Methods utilized, see Interpolation Method Used For Smooth and Smooth & Contour Methods. Select OK.

7. Select the OK button and the cursor becomes a grid. Hold down the left-mouse button and drag the grid so that the map being smoothed falls within desired grids. When the mouse button is released, a new view of the layer will be created and displayed.

Smoothing Over Defined Boundaries

You can Smooth point data and show averages for the data over drawn and defined areas (known as polygons) at any time. This option is useful for showing average yields for different areas of your farm: soil types, for example.

To create averaged data over defined boundaries:

1. Make sure the area/polygon layer to which the data will be averaged is the Active Layer: a soil type layer, for example.

2. Use the Pointer Tool to select the area(s) to average. To select more than one area, hold down the Shift or Ctrl key on your keyboard while clicking on each area. Alternately, click and drag to "rubber band" or lasso the areas you wish to select.

3. Right-click on one of the selected areas and select Average Polygons from the menu.

4. In the Average Polygons box, select the layer to be averaged. This will be the point-based layer, such as yield or soil test data.

5. Select the OK button. The selected layer will have a new sublayer created with the averages for the selected polygon(s).

Advanced Options Box

The Advanced Options box will appear when you click on the Options button in the Smoothing box. The Advanced Options box is relevant to both Smoothed and Smoothed & Contoured views.

The following areas are accessible through the Options box:

• Number of Points to use in calculation: This is the number of points that the program will try to find within a set distance for the calculation. If this value is set too high it will slow down the time of the smoothing. If this value is set too low you will get inaccurate results. The value should be set to the number of points that can be found within a grid square.

• Ignore Data Points this distance away: The program will look a set distance for other points to include in the calculations. This value can be .75 to 1.5 times the size of the grid. Increasing this value may give you better results but will increase the time required for smoothing.

• Minimum Area: The minimum area is used for contour items only. When generating the polygon for each area, if the acres are less than this value, the polygon will be combined with a surrounding polygon.

Interpolation Method Used for Smooth and Smooth & Contour Methods

Farm Site and Site Pro use inversed distance to interpolate the value of each point within the grid. Simply put, when using the Smooth and Smooth & Contour Methods, each area will be filled with a weighted average for the data within and around that grid.

Specifically Farm Works creates a grid of the user-specified size. This is the Grid Resolution in the Smoothing box. The smaller the value, the more points will be created and the smoother the contour map will be. If the value is too large, some variations in the field will be lost.

The value of each grid point is determined by first finding the N closest actual sample points, where N is the value the user enters in the Smoothing Options box for Number of data points to use in calculation. Points that are too far away should not be considered as having an effect on the value at the point being calculated. The user can set this distance in the Ignore data points over this distance away box. These two options determine which points are used in the calculation.

Once the points to use in the calculation are determined, Farm Works uses the distance of each sample point from the point being calculated to weight its contribution to the final value. The amount each sample contributes is directly proportional to its distance away, i.e. inverse distance. For example, in the illustration to the right, Point B will affect X, or the Calculated Point, much more than Point A and Point C because of their greater distance from X. Only points within the Calculated Points' grid will affect X.

Methods used by other programs may use a different weighting that uses the distance raised to a power to calculate the weighting, such as inverse distance squared. Interpolation is a complex topic and each method can give different results. This is especially true at the edges of the calculated grid due to the lack of data.

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Call us at at 877-585-6761 and ask for Lorra.