How to compute residential walls with sight of trees
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For the 3-30-300 guidelines, the rule indicated by the "3" is the ability to see 3 trees out of residential windows. This can be computed in the Tygron Platform by calculating the locations of residential walls, and the sight-lines onto trees.
How to compute residential walls with sight of trees:
- Add an Attribute to the Function of Default Deciduous Trees, naming the attribute TREE_SIGHT_DISTANCE.
- Configure the value of the TREE_SIGHT_DISTANCE of Default Deciduous Trees as "100".
- Add a Sight Distance Overlay, configured so that:
The Attribute it references is TREE_SIGHT_DISTANCE. - Create a Grid Overlay of residence walls.
- Add a Combo Overlay, configured so that:
Input A: The Grid Overlay of residence walls.
Input B:The Sight Distance Overlay for the sight onto trees.
Formula:IF(EQ(A, 0), NO_DATA, GT(B, 0))
- Configure the legend of the Combo Overlay to have a distinct entry for the value "0" and the value "1".
Notes
- The resulting Combo Overlay has values of 0 where there are walls without sight of a tree, and values of 1 where there are walls with sight of a tree.
- Although the different steps in the calculation may produce coarse results, over a large scale the imperfections can balance out and the calculation as a whole can provide relevant insights into the compliance to the guideline.
- At this time this calculation can only determine sight-lines to a tree, not necessarily to the prescribed 3 or more trees. However, in most urban environments trees exist in groups which can alleviate the discrepancy somewhat.