How to improve the estimated foliage overlay
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This how-to assumes you have followed the previous how-to on how to estimate foliage height using an Infrared WMS Overlay. The how-to ends with a combo overlay that estimates the foliage height based on infra red images, a color filtering overlay and the subtraction of the surface and terrain height overlays. The resulting overlay provided a reasonable height for the tree trunks, but less for the branches of the trees. This how-to tries to improve the estimated foliage.
How to improve the estimated foliage overlay:
- Hover over Overlays in the ribbon bar, and under Grid Calculation select Average and Interpolation.
- In the Average Overlay's detail panel, click on the Configuration Wizard button.
- In the Operator step of the wizard, select the MAX option.
- In the Type step select Input based on an other Grid Overlay.
- In the Overlay step select the Custom Foliage Height overlay that we created using the previous how-to.
- Select finish to close the wizard.
- In the Average Overlay's detail panel, select the Cell averaging distance field and provide the value '12'.
- Click on the update now button to calculate the Average Overlay.
- Hover over Overlays in the ribbon bar, and under Grid Calculation, select Combo.
- In the combo Overlay's detail panel, select the name field and name it Improved Foliage Height.
- Select the combo box for Grid Input A and select the Custom Foliage Height Overlay.
- Select the combo box for Grid Input B and select the Average Value Overlay.
- Select the formula field and type the following formula:
IF(GT (A, 0) , B , 0). - Select the update now link to calculate the Improved Foliage Height.
Estimated foliage height.
Improved estimated foliage height.
Notes
- The average distance of 12 meters is not set in stone, alternative average distances can be used.