angular_velocity: angular velocity of eye movement

In rwoldford/EyeFixR: Determinations fixation locations from eye-tracking data

Usage

angular_velocity(data, xDist, yDist)

Arguments

data
xDist
yDist

Examples

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function (data, xDist, yDist) 
{
    data$AngularVelocity <- rep(NA, nrow(data))
    for (i in 2:nrow(data)) {
        if (!is.na(data$GazePointX[i]) & !is.na(data$GazePointX[i - 
            1])) {
            timeDiff <- (data$Timestamp[i] - data$Timestamp[i - 
                1]) * 10^(-6)
            x <- (data$EyeLocX[i] + data$EyeLocX[i - 1])/2
            y <- (data$EyeLocY[i] + data$EyeLocY[i - 1])/2
            z <- (data$EyeLocZ[i] + data$EyeLocZ[i - 1])/2
            a <- sqrt(z^2 + (x - xDist * data$GazePointXSmoothed[i])^2 + 
                (y - yDist * data$GazePointYSmoothed[i])^2)
            b <- sqrt(z^2 + (x - xDist * data$GazePointXSmoothed[i - 
                1])^2 + (y - yDist * data$GazePointYSmoothed[i - 
                1])^2)
            c <- sqrt((xDist * data$GazePointXSmoothed[i] - xDist * 
                data$GazePointXSmoothed[i - 1])^2 + (yDist * 
                data$GazePointYSmoothed[i] - yDist * data$GazePointYSmoothed[i - 
                1])^2)
            angle <- 180/pi * acos((a^2 + b^2 - c^2)/(2 * a * 
                b))
            data$AngularVelocity[i] <- angle/timeDiff
        }
    }
    return(data)
  }

rwoldford/EyeFixR documentation built on May 12, 2019, 4:37 a.m.