trackdem

---

Particle tracking and demography

A test version of this package has been released (0.1 on CRAN), bug reports and comments are .

Abstract

The aim of trackdem is to obtain unbiased automated estimates of population densities and body size distributions, using video material or image sequences as input. It is meant to assist in evolutionary and ecological studies, which often rely on accurate estimates of population size, structure and/or individual behaviour. The main functionality of trackdem includes a set of functions to convert a short video into an image sequence, background detection, particle identification and linking, and the training of an artifical neural network for noise filtering.

Installation

trackdem can now be installed from CRAN or from github.

## Install from CRAN
install.packages('trackdem')

## Install from Github
## devtools is required
require(devtools)
install_github("marjoleinbruijning/trackdem")

To use the automated video to image and metadata creation function from trackdem users need Python 2.7, Libav and ExifTool.

Ubuntu users can paste the following commands in a terminal to install libav and ExifTool (Python 2.7 should be included by default):

sudo apt-get update
sudo apt-get install libav-tools
sudo apt-get install libimage-exiftool-perl

Mac users can paste the following commands in a terminal to install libav:

## Make sure that homebrew is installed, see: https://brew.sh/
## Install libav
brew install libav

ExifTool can be downloaded from here. Follow the installation instructions for the OS X Package. The newest
Python 2.7 release, if not installed yet, can be downloaded here.

Windows users can download libav here. Download the latest nightly-gpl release, and extract all files to a chosen location. Next, download the file named libgcc_s_sjlj-1.dll, and place it within the libav directory, in '/usr/bin'. ExifTool can be downloaded here. For ExifTool, download the stand-alone executable and place the exiftool(-k).exe file in a chosen directory. For convenience, you can change the name to exiftool.exe, as described in the installation instructions. Finally, Python 2.7 can be downloaded here. Follow the instructions for installation.

Examples

## Load package
require(trackdem)

########################################################################
## Simulate image sequence
########################################################################
dir.create('images')
a <- getwd()
setwd('images')
set.seed(100)
## Create image sequence (this takes a moment)
traj <- simulTrajec(nframes=30,nIndividuals=20,domain='square',
                    h=0.01,rho=0.9,staticNoise=FALSE,
                    sizes=runif(20,0.004,0.006))
setwd(a)

########################################################################
## Analyze image sequence
########################################################################
## Load images
dir <- 'images'
allFullImages <- loadImages (dirPictures=dir,nImages=1:30)
allFullImages
class(allFullImages)
plot(allFullImages,frame=1)

## Detect background
stillBack <- createBackground(allFullImages,method='mean')
stillBack
class(stillBack)
plot(stillBack)

## Subtract background
allImages <- subtractBackground(bg=stillBack)
allImages

## Identify moving particles
partIden <- identifyParticles(sbg=allImages,
                              pixelRange=c(1,500),
                              autoThres=FALSE,threshold=-0.1)
summary(partIden)
attributes(partIden)$threshold
plot(partIden,frame=10)

## Reconstruct trajectories
records <- trackParticles(partIden,L=60,R=3)
summary(records)
summary(records)$N # population count
summary(records)$particles[,'Size'] # body size distribution
summary(records)$particles[,'Total movement'] # movement distribution
summary(records)$area # area covered by particles
summary(records)$presence # minimum presence
dim(records$trackRecord)
dim(records$sizeRecord)
dim(records$colorRecord)

## Obtain results
## Trajectories
plot(records,type='trajectories')
for (i in 1:length(unique(traj$id))) {
  lines(traj$x[traj$id==i],traj$y[traj$id==i],col="grey",
	    lty=2,lwd=2)
}

Examples of output

Future features

Allow different numbers of color layers (e.g. for black and white images).