Core Boundary — The Core Boundary script creates a shape file that contains core areas which include interspersions and inclusions.


A patch in Patchworks is defined as a connected set of topologically adjacent polygons, with all polygons in the set having a value for a specified patch membership criterion attribute that is greater than a specified threshold level. For example, a patch might be all conifer dominated forest polygongs over 80 years of age within 200m of each other.

However, in the definition of a core, a limited interspersion of other forest or non-forest types may be permitted. Thus a patch can be equated with "net" area and a core with "gross" area.

The Core Boundary script uses the CoreBoundary class to perform a rasterization of the input dataset (which includes patches) and computes the area that falls within patches as well as the area that is in the buffer around the patches. The buffer is computed by dilating and eroding the raster patches by the specified buffer distance. The output is a shape file that has all of the patch and buffer polygons, and all of the additional requested attributes. Thus patches plus buffers equals core area. This output shape file will represent the core areas described above. Each polygon in the resulting shapefile is identified as being part of the patch or the interspersion.


This script essentially turns "patches" into "cores". Figure 188, “Contrasting a patch and a core” explains how patches relate to cores.

Figure 188. Contrasting a patch and a core

Core areas represent the featured vegetation type (vertical hatch) as well as inclusions and interspersions or non-featured types (diagonal hatch). The thick black line shows the boundary of this core. The patch represents only the featured vegetation type (vertical hatch).

Figure 189, “An example of a patch and a core” illustrates the input and output shape file for the core boundary tool.

Figure 189. An example of a patch and a core

The shape on the left represents the patch area (dark) recognized by the spatial model, and the shape on the right shows the output of the core boundary tool including patch areas (dark) plus the non-habitat interspersion (light).


      CoreBoundary.makeCoreBoundary(control.getBlockTable(),                    1
                                    10,                                         2
                                    200,                                        3
                                    "",              4 
                                    4,                                          5
                                    "feature.core.lateConifer.size>=3000",      6
                                    control.getBlockTable(),                    7
                                    new String[] {"LABEL","TOTALAREA",          8
                                    new String[] {"LABEL", "TOTALAREA", "CORE_ID","CORE_SIZE","UNMANAGED"},9
                                    "coreboundary/r_1_4");                                               10 


patchCover - The table that defines the location of the patches. In this example, it is the block table


cellsize - The size of the raster cell, in this example, 10 m.


bufferDist - The distance that should be used for the dilate and erosion. In this example, it is 200 m.


patchLabel - The name of the column in the patchCover that contains the patch identifiers (


period - The planning period that should be interrogated for patch labels, in this instance, 4.


reselect - An expression that is used to filter out irrelevant polygons. In this example, we are only interested in those polygons belonging to a patch greater than 3000 ha.


invCover - The table that defines the content of the cores. This is the same as the patchCover.


columns - A list of column names that should be copied to the output file.


labels - A list of labels to be applied to the columns that are copied. Patchworks supports long names, but shapefiles are limited to 9 character column names. In the example above, some labels are the same as the column names and some are different.


ouputname - The name to be given to the output shapefile. Do not specify the ".shp" extension. The output shape file in the above example is in the directory "coreboundary" and is called "r_1_4"

See Also