Combo Overlay with masking: Difference between revisions

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==Use Case Description==
==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?
How can I 'mask' (filter out) all values of a rainfall overlay that is not of the highest range? In this case we use the default highest range of 50 cm or more.


For this we need to create two [[Average Overlay|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|rainfall overlay]] to have as a 'filter' over the combination of the other two overlays.
For this we need to add a [[Rainfall Overlay|rainfall overlay]] and a formula we can use to mask the values that are too low.


<gallery>
<gallery>
Image:AVG_Social1.jpg|Average Overlay SOCIAL housing
Image:AVG_Normal1.jpg|Average Overlay NORMAL housing
Image:Rainfall_Overlay1.jpg|Rainfall overlay
Image:Rainfall_Overlay1.jpg|Rainfall overlay
Image:Combo_Distance_Filtering1.jpg|Combo Overlay with distance filtering
</gallery>
</gallery>



Revision as of 15:41, 8 December 2020

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

Use Case Description

How can I 'mask' (filter out) all values of a rainfall overlay that is not of the highest range? In this case we use the default highest range of 50 cm or more.

For this we need to add a rainfall overlay and a formula we can use to mask the values that are too low.

Formula

As we want to indicate the and combine the area that is within the range of all three buildings, the formula for the use case, based on the operators table on the combo overlay page, looks like this:

MIN(A, B, C)

Where A, B and C are the average grid overlays.

How to

How to add a Combo Overlay with features:
  1. Give each building or area you want to include a specific attribute (ex: 'FOO', 'BAR', 'BOO',...)
  2. Create three Average Overlays, set the cell averaging distance to the desired range
  3. Add a Combo Overlay and select the Average overlays in each slot (A,B and C)
  4. Enter the formula in the Formula field
  5. Select 'Update Now' in case auto-update was disabled