The Trajectories module allows the user to easily log (measure) the trajectories of in situ growth of root systems from tracings/digitize images. Unlike the other operations in this program, this module relies on input from the user for all output data. Trajectories are estimated by "drawing lines" over individual roots in the image loaded into BranChing. Each line you draw is logged as a vector - having a magnitude (length) and direction (relative horizontal and vertical components).
You can use as many line segments as you wish to describe the trajectory of a root. As you are drawing the line, BranChing shows you the magnitude (corrected by the image scale) and direction of the vector. Thus, it is a simple task to use an indeterminate number of vectors of constant magnitude to summarize a given trajectory.
Figure 4. Example of trace of root system and potential set of vectors used to represent trajectories of lateral roots. The vectors used to summarize each root's trajectory are of equal magnitude (except for the terminal vectors).
 
Details
When an image is opened you will be asked to create the output (results) file before you begin. All of the vector information for created for the image is stored in this file.
Before defining the vectors in the image you will be asked by BranChing to "Define Horizon". This action tells BranChing how the image is rotated. To define the horizon simply draw a line over the horizon in the image (the line that would be parallel to the surface of the soil).
In most cases, you will be defining trajectories (sets of vectors) for more than one image or you will be logging individual vectors of different "classes". For example, in the above figure (Figure 3), there were 3 different lateral roots that were defined by several vectors each. In another context you may have a root tracing made by tracing roots at several dates. You may wish to classify vectors on the basis of age.
Whatever the use of different "classes" of vectors, BranChing allows you to log up to 10 different classes of vectors. The classes are numbered sequentially from 1 to 10. Initially you start logging into class "1". You can change the set a given vector is logged into by pressing a key 1-0 (where 0 = 10). BranChing includes writes the current class into the output file for each vector.
Each vector is written to the output file as a separate line as they are created. For each vector, the following information is recorded (the text enclosed by [] for each entry is the label for the item in the output text file):
Class (1-10, user defined) [Int]
Length (magnitude) of Vector [L]
Direction (heading or angle) of Vector [°]
Direction (heading or angle) of Vector, corrected by the HORIZON of the image [°corr]
Horizontal Displacement [∆H]
Vertical Displacement [∆V]
The Trajectories module is a one-input one-output job. That is, BrancChing creates a single output TEXT file for each root system processed. The Result Window is not updated by this module.
