getVoxelHull Compute the voxel hull of a point cloud.
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  DESCRIPTION/NOTES
  * The voxel hull is a low resolution representation of the volume occupied by
    a point cloud. For the computation of the voxel hull the object space is
    subdivided into a voxel structure. The voxel hull of the point cloud
    consists of all voxels which contain at least one point of the point cloud.
 
  * Only active points are considered for the computation of the voxel hull.
 
  * The voxel hull can be used to select points, which are overlapping with
    another point cloud. An example for this task is given in the documentation
    of the 'select' method. For this call 'help pointCloud.select' and see the
    examples for the 'InVoxelHull' selection strategy.
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  INPUT
  1 [voxelSize]
    Voxel size (equal to edge length) of a single voxel.
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  OUTPUT
  1 [obj]
    The voxel hull is attached to the following properties of the ouput object:
    * obj.voxelHull          = n-by-3 matrix containing the x, y, z coordinates 
                               of the centers of the voxels
    * obj.voxelHullVoxelSize = edge length of voxels (given by parameter
                               voxelSize)
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  EXAMPLES
  1 Import a point cloud and compute its voxel hull.
    pc = pointCloud('Lion.xyz');
    pc.getVoxelHull(5); % voxel size is 5mm
    % The voxel hull can now be found in pc.voxelHull and pc.voxelHullVoxelSize 
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  philipp.glira@gmail.com
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