R: Calculate Boyer's (2008) relief index for a surface
RFI
R Documentation
Calculate Boyer's (2008) relief index for a surface
Description
A function that calculates relief index following Boyer (2008) Relief index of
second mandibular molars is a correlate of diet among prosimian primates and
other mammals. J Hum Evol 55:1118-1137 doi: 10.1016/j.jhevol.2008.08.002
Usage
RFI(plyFile, alpha = 0.01)
Arguments
plyFile
An object of classes 'mesh3d' and 'shape3d'
alpha
Step size for calculating the outline. See details
Details
The function requires an object created by reading in a ply file utilizing
either the read.ply or the read.AVIZO.ply function, with calculated normals.
Relief index is calculated by the ratio of three-dimensional surface area to two
dimensional area on meshes that represent specimen surfaces and have already
been pre-smoothed in a 3D data editing program. Alignment of the point cloud
will have a large effect on patch orientation and must be done in a 3D data editing
program or auto3dgm prior to creating and reading in the ply file. The mesh
must be oriented such that the occlusal plane is parallel to the X- and Y-axes and
perpendicular to the Z-axis.
Some files may fail with pancake[TempF,] : subscript out
of bounds. In these files it may be necessary to increase
the alpha value which is default set to 0.01. Increasing the
alpha value can cause the RFI function to over-estimate
the size of the footprint. Caution should be exercised when
troubleshooting by adjusting alpha