How to compute residential walls with sight of trees

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 sightlines 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 Decidious Trees, naming the attribute TREE_SIGHT_DISTANCE.
2. Configure the value of the TREE_SIGHT_DISTANCE of Default Decidious 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 sightlines to a tree, not neccesarily to the prescribed 3 or more trees. However, in most urban environments trees exist in groups which can alleviate the discrepancy somewhat.

See also

• Demo 3-30-300 Project