Naturalized Fruit Planting Mapping Procedure

The Naturalized Fruit Planting Map was generated by INTERPNT which is a tree mapping program that uses distance measurements and tree diameter. According to Jerry Weimer, a graduate student in the Biology Department at Missouri State, "INTERPNT, developed at Harvard Forest at Harvard University, is based on trilateration (used distance measures) using three points for a reference. Basically, we used three reference points and measured the distance to each of those from a target tree. These three distances can then be used to get three estimates for the location of the target tree. The three estimates are then averaged together to get a decent estimate of the location of the target tree. The three estimates come from the three triangles formed by the three reference trees and target tree( RA,B,C = Reference tree A,B,C and T = Target tree). RA-RB-T  RB-RC-T and RA-RC-T.   There are a few reasons for having three reference trees. One, it gives you a better initial estimate of the location. Two, if you make an error you can tell which measurement is probably the wrong one, because one of the estimates for location will be considerably different than the other two. I think that is why sailors back in the day always carried three compasses, so that way they new if one was wrong. Third, if you do a network adjustment with the points you need the third difference so that you have enough degrees of freedom. When you set up the observation equations, you are estimating two values (x and y) for each point. Therefore you need another distance measure so that you have some degrees of freedom left. If you have three distance measures you end up with the degrees of freedom being the number of points you are estimating. 2*no. of points (x's an y's) - no. of points = no. of points."

You use triangulation to determine the first set of reference trees A, B, and C.  The two trees or points (A and B) are measured and set as reference and the third tree or point (C) location is determined by measuring the distance from tree A to C and then Tree B to C. 

Each time you measure a tree, you have to tag it with a number.  The first two trees referenced are 1=A and 2=B and the third tree C=3.  From there, each subsequent tree that is measured from three reference points is given the next number and the three reference trees that were used are recorded for use when inputting the data into the INTERPNT program.

Each time you determine the location of a Target tree - you can then use that point or tree as a reference point A, B or C so you can move through a planting of trees using different reference points as you go.

The program can be downloaded from the INTERPNT site. See the map of the Naturalized Fruit Planting Area that was generated from this process.