R: Volumetric Analysis using Graphic Double Integration

# Volumetric Analysis using Graphic Double Integration

## Documentation for package ‘gdi’ version 1.10.0

- DESCRIPTION file
- User guides, package vignettes and other documentation
- Package NEWS

## Help Pages

cscorr | Measure and analyze cross-sectional geometry supplied as an image.
csI | Calculates the second moment of area (=area moment of inertia, Ix and Iy) and polar moment of inertia (Iz or J) for a cross-section given as an image.
expandConvexHull | Estimate soft tissue expansion factors following Macaulay et al. 2023
fdetect | Tool to help determine which threshold value and method to use with measuresil() or cscorr(). The function analyzes all pixels along the edges of the image to determine the background color, to help with deciding on appropriate settings and avoid errors introduced by inappropriate settings
gdi | Estimate volume using Graphic Double Integration.
hCOM | Finds the horizontal (x axis, i.e. the axis vertical to the cross-sections) position of the center of mass (COM) of the volume. Experimental; only valid for "raw" gdi results with segment volumes approximated as elliptical prisms, or for manually supplied segment COMs. COM is calculated as a weighted mean of all segment COMs, with the segment mass as the weighting factor.
imghist | Simple histogram analysis for all color values in an input image. Can be used to help assess whether a chosen threshold value is appropriate for differentiating the silhouette from the background, or for general image analysis purposes.
inter_corr | Helper function for interpolating cross-sectional metrics over the length of a silhouette
measuresil | Take pixel-by-pixel measurements of a silhouette in jpeg or png format for use with the gdi function.
plot_sil | Plots a silhouette read by measuresil()
rotI | Calculates the rotational inertia of a body. Only works with simple circular/elliptical and rectangular cross-sections, thus pixel-precise estimates are recommended.
sellipse | Estimate area of a superellipse. Assistant function for gdi.
sellipse.coo | calculate coordinates for plotting a superellipse for visualizing body cross-sections
transfer_ratio | Transfer a vector of aspect ratios onto another body profile
vCOM | Finds the vertical (y axis, i.e. the axis parallel to the cross-section diameter) position of the center of mass (COM) of the volume. Experimental; only valid for "raw" gdi results with segment volumes approximated as elliptical prisms, or for manually supplied segment COMs. COM is calculated as a weighted mean of all segment COMs, with the segment mass as the weighting factor. Estimates have lower accuracy compared to hCOM, because cross-sectional geometry and variation in density throughout the cross-section is not taken into account.