This function and associated methods will ultimately take a collection
Stem" subclass objects and check that
they all lie within the associated "
object. In addition, if some objects lie either paritally or completely
outside the tract, the routine will return a new collection with only
those portions of the collection that lie completely within the
boundaries of the tract if desired. This function is especially helpful
when using either the ‘mirage’ or ‘walkthrough’ methods to
correct for boundary overlap.
A collection of “
See methods for other possible arguments.
It is possible to have a collection of stems where some individuals do not lie completely within a desired tract or plot in sampSurf. When using buffered tracts, it is fine if some individuals intersect the internal buffer, as long as the respective inclusion zones do not overlap the external boundary. There are circumstances when it is advantageous to clip any tree or log that lies outside the tract out of the population. In addition, logs can intersect the tract boundary, and clipping the external part that is not within the tract is also sometimes useful. This is especially true when using either the mirage or walkthrough boundary correction methods.
One can invoke this function through the appropriate method and it will
remove any stem that lies completely outside the tract, and also clip
any logs to the tract boundary. If one desires only to check whether any
stems are offending in this way, that option is also available. For
standingTree” objects, the center location must lie
outside the tract. For “
downLog” objects, the entire
needle must lie outside the tract before the object is removed. If the
needle intersects the tract, the external portion is clipped
This generic function has several methods
clipStemsToTract-methods, which should be consulted for
more details on its use. Note that the method for buffered tracts clips to the
internal buffer by default, but one can alternatively choose to clip to
the tract boundary if desired.
The data returned are in
list form with components...
A data frame with as many rows as there are stems in the collection originally passed to the function. Columns identify which stems lie inside, outside and intersect, and if the latter, on which cardinal direction leg of the tract that occurs (can be more than one, e.g., in a corner).
A simple numeric summary of stems lying inside, outside and intersecting.
The new collection of stems (or
Please note that only two of the
clipStemsToTract-methods methods should actually be
called by the casual user. The others simply set up the control flow
for doing all the dirty work.
Jeffrey H. Gove
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# # make a smaller "plot" inside the large one and clip... # ## Not run: btr = bufferedTract(.1, Tract(c(x=50,y=50), cellSize=1)) bb = bbox(btr) bb[,1] = 20 bb[,2] = 40 smtr = Tract(bb, cellSize=1) dlogs = downLogs(100, btr) dlogs2 = clipStemsToTract(dlogs, smtr, runQuiet=FALSE, showPlot=TRUE) dlogs2$status ## End(Not run)
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