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.

Editor → Current Situation (Ribbon tab) → Overlays (Ribbon bar)
How to compute residential walls with sight of trees:
  1. Add an Attribute to the Function of Default Deciduous Trees, naming the attribute TREE_SIGHT_DISTANCE.
  2. Configure the value of the TREE_SIGHT_DISTANCE of Default Deciduous Trees as "100".
  3. Add a Sight Distance Overlay, configured so that:
    The Attribute it references is TREE_SIGHT_DISTANCE.
  4. Create a Grid Overlay of residence walls.
  5. 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))
  6. 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.

See also