Combo Overlay with distance filtering

This page describes a use case for implementing a combo overlay.

Use Case Description

In an area, the locations for social and normal housing are known. Where does severe rainfall (50cm or higher) have impact on social and normal housing?

For this we need to create two average grid overlays, one for social housing and one for normal housing, by selecting the respective category wieght attributes; SOCIAL_CATEGORY_WEIGHT and NORMAL_CATEGORY_WEIGHT. Give each overlay a cell averaging distance of 30m. We also need to add a rainfall overlay to have as a 'filter' over the combination of the other two overlays.

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  Average Overlay SOCIAL housing

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  Average Overlay NORMAL housing

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  Rainfall overlay

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  Combo Overlay with distance filtering

Formula

Using the operators table, this gives us the following formula:

MUL(OR(GT(A, 0.1), GT(B, 0.1)), C25)

Where C25 is the last time frame of the rainfall overlay.

How to

How to add a Combo Overlay with masking:

1. Add a rainfall overlay (give it a significant rain event)
2. Add a Combo Overlay and select the rainfall overlays in slot A
3. Enter the formula in the Formula field
4. Enable and adjust a custom legebnd as desired
5. Select 'Update Now' in case auto-update was disabled

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  Add a rainfall overlay

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  Select the rainfall overlays in slot A

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  Enter the formula in the Formula field

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  Adjust a custom legend

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  Select 'Update Now'