curves2d: Select points to "slide" along two-dimensional curves.

Description

An interactive function to select 2d "sliding" semilandmarks along curves.

Usage

curves2d(file, nsliders)

Arguments

file

Name of sample file in working directory (can include path) containing two-dimensional landmark data. File names can be written in manually, including paths, or obtained using directory/file manipulation functions e.g.,

nsliders

Number of landmarks to slide along curves.

Value

Function returns an n-x-3 .nts file containing the positions along which each of n chosen semilandmarks will "slide". e.g., "4 3 2", semilandmar 3 will slide between 4 and 2.

Details

This function selects points on the created template to "slide" along 2d curves lacking known landmarks (see Bookstein 1991:376-382, 1997 for algorithm details). Each sliding semi-landmark (sliders) will slide between two designated points, along a line tangent to the specified curvature. Using the right mouse button, users: 1. Select sample "2dcoords.nts" file digitized using function digitize2d 2. Select the first point between which semi-landmark will "slide" 3. Select sliding semi-landmark, 4. Select point along which sliding trajectory will end. Screen plot shows arrows connecting the three points, and direction of "slider" semilandmark. The LEFT mouse button is used to select points.

References