Arborography: Mapping a Tree in 3 dimensions
In the branching logic definition, multiple "children" branches sprout from a single "parent" branch. Each branch is given a unique name that traces its parentage.
The letter "b" is used as a divider character. The number before is the height in metres at which this branch is connected to the trunk. The first number after is to identify which branch is attached to the trunk at that height, and the subsequent digits identify which child branch.
Thus, "42.8b23"is the 3rd branch connected to the 2nd branch connected to the trunk at 42.8 metres from the ground, as measured by a tape stretched from the ground.
This system can be used to any degree of branching resolution. It can be adapted to trees without distinct trunks by abandoning the first portion of the name.
Vectors are used to describe the geometry of a tree. A vector is a line in space and can be defined by three measurements in spherical space:
1)Slope: Angle measured with a clinometer between horizon at 0 degrees and straight up away from Earth at 90 degrees. Straight down to the ground is -90 degrees.
2)Azimuth: Compass angle in degrees with North= 0, E=90, S=180, W=270. (Don't forget the magnetic declination!)
3)Distance: A measurement of distance in metres by tape measure, laser rangefinder, or estimation.
)
or
Cylinders (
).
Vectors can be turned into a cone by adding a start circumference only, or to a cylinder by measuring both a start and end circumference.
Branches are simplified into a cone when they cannot be measured in any more detail. Cones have no children branches.
Cylinders (which are technically "truncated cones") are used for large branch segments. Cylinders usually have children branches.
If a branching junction is the farthest that can be accessed, the parent branch is measured as a cylinder, and children branches measured as cones.
Think of your upper arm and forearm and palm as cylinders, and your fingers as cones.
The trunk of the tree is measured as a series of stacked cylinders by recording a circumference at regular intervals. Dead branches that have cracked and lost their ends are sometimes modeled as cylinders with no children.
Cones representing branches with foliage are further elaborated by creating a field of lines to encompass the volume of the foliage and outer branches. By adding a down, up, left, and right vector to the central cone, the map shows more than just the wood skeleton. Nominal "Foliar units" are used to quantify the amount of foliage on each branch.
Some branches arising from the trunk are non-radial, that is, they are not attached to trunk in the same direction that they point. The azimuth from the tree's center to the branch attachment can be recorded as distinct from the vector azimuth. Resprout branches or epicormic shoots often develop branches on one side of the tree that grow in other directions. These resprout branches are often very shallowly embedded - they are only connected into the wood from the point at which they originated. Original branches are often radial and embedded deeply into the tree, having originated when the tree was a narrow terminal shoot.
Notable structural attributes, traps, and survey stations are photographed and recorded in this mapping framework as best as possible. A method to depict traps in the appropriate 3 dimensional locations is being developed. Difficulties have arisen with scale: an image depicting a trap 15cm square on a 70m tree shrunk to a 25 cm computer screen does not get interpreted well by the human eye .
