/// <summary>
/// I-VT algorithm from "Identifying fixations and saccades in eye-tracking protocols", Salvucci, 2000
/// </summary>
/// <param name="maxSpeedFixation">If the speed is inferior to maxSpeedFixation, it is considered as a fixation</param>
public void fixationVelocity(int maxSpeedFixation = 40)
{
//With Tobii EyeX, the distance and velocity are similar because the data is recorded at a regular time - every x ms)
//Compute the velocity
for (int i = 1; i < gazes.Count; i++)
{
gazes[i].squaredVelocity = (gazes[i - 1].gazeX - gazes[i].gazeX) * (gazes[i - 1].gazeX - gazes[i].gazeX) + (gazes[i - 1].gazeY - gazes[i].gazeY) * (gazes[i - 1].gazeY - gazes[i].gazeY);
}
List <Gaze> fixations = new List <Gaze>();
for (int i = 0; i < gazes.Count; i++)
{
List <Gaze> microFixations = new List <Gaze>();
int j = 0;
while (i + j < gazes.Count && gazes[i + j].squaredVelocity < maxSpeedFixation * maxSpeedFixation)
{
microFixations.Add(gazes[i + j]);
j++;
}
if (microFixations.Count > 1)
{
//Compute the centroid
Gaze centre = centroid(microFixations);
fixations.Add(centre);
i += j - 1;
}
if (microFixations.Count == 1)
{
fixations.Add(microFixations.First());
}
}
gazes = fixations;
}
private IEnumerable <Gaze> readTobiiCsvNew(List <string> linesTxt, char split = ';')
{
List <Gaze> gazes = new List <Gaze>();
if (linesTxt.Count < 2)
{
return(gazes);
}
//Remove the header
linesTxt.RemoveAt(0);
//Convert decimal marker in numbers if the format it is a dot or a comma 00.000 (USA / Japan) or 00,000 (Europe)
double timeZero = double.Parse(linesTxt[0].Split(split)[1].Replace(',', '.'), new CultureInfo("en-US"));
foreach (string line in linesTxt)
{
string[] cols = line.Split(split);
Gaze g = new Gaze();
g.windowTime = DateTime.ParseExact(cols[0], "MM/dd/yyyy HH:mm:ss.FFF", null);
g.timestamp = (float)(double.Parse(cols[1].Replace(',', '.'), new CultureInfo("en-US")) - timeZero);
g.gazeX = float.Parse(cols[2].Replace(',', '.'), new CultureInfo("en-US"));
g.gazeY = float.Parse(cols[3].Replace(',', '.'), new CultureInfo("en-US"));
g.pupilDiameter = float.Parse(cols[4].Replace(',', '.'), new CultureInfo("en-US"));
gazes.Add(g);
}
return(gazes);
}
private void readSMiRaw(List <string> linesTxt)
{
//Remove the non-data lines
string curentLine = linesTxt[0];
int indexGazeX = 0;
int indexGazeY = 0;
while (curentLine.StartsWith("##") || curentLine.StartsWith("Time"))
{
//Save the saze of the screen
if (curentLine.StartsWith("## Calibration Area: "))
{
width = int.Parse(curentLine.Split('\t')[1].Replace(',', '.'), new CultureInfo("en-US"));
height = int.Parse(curentLine.Split('\t')[2].Replace(',', '.'), new CultureInfo("en-US"));
}
//Save the index of the collomn that contain the position of the gaze, because it change depending on the files!
else if (curentLine.StartsWith("Time"))
{
string[] cols = curentLine.Split('\t');
for (int i = 0; i < cols.Length; i++)
{
if (cols[i] == "R POR X [px]")
{
indexGazeX = i;
}
else if (cols[i] == "R POR Y [px]")
{
indexGazeY = i;
}
}
}
linesTxt.RemoveAt(0);
curentLine = linesTxt[0];
}
double timeZero = double.Parse(linesTxt[0].Split('\t')[0].Replace(',', '.'), new CultureInfo("en-US"));
foreach (var line in linesTxt)
{
string[] cols = line.Split('\t');
if (indexGazeX < cols.Length && indexGazeY < cols.Length)
{
Gaze g = new Gaze();
g.timestamp = (float)(double.Parse(cols[0].Replace(',', '.'), new CultureInfo("en-US")) - timeZero);
g.gazeX = float.Parse(cols[indexGazeX].Replace(',', '.'), new CultureInfo("en-US"));
g.gazeY = float.Parse(cols[indexGazeY].Replace(',', '.'), new CultureInfo("en-US"));
gazes.Add(g);
}
}
}
public static Gaze centroid(List <Gaze> gazes)
{
Gaze g = gazes.First();
g.duration = gazes.Last().timestamp - g.timestamp;
for (int i = 1; i < gazes.Count; i++)
{
g.gazeX += gazes[i].gazeX;
g.gazeY += gazes[i].gazeY;
}
g.gazeX /= gazes.Count;
g.gazeY /= gazes.Count;
return(g);
}
public static List <Gaze> readTobiiCsv(List <string> linesTxt, char split = ';')
{
List <Gaze> gazes = new List <Gaze>();
if (linesTxt.Count < 2)
{
return(gazes);
}
//Remove the header
linesTxt.RemoveAt(0);
//Convert decimal marker in numbers if the format it is a dot or a comma 00.000 (USA / Japan) or 00,000 (Europe)
double timeZero = double.Parse(linesTxt[0].Split(split)[0].Replace(',', '.'), new CultureInfo("en-US"));
foreach (string line in linesTxt)
{
string[] cols = line.Split(split);
Gaze g = new Gaze();
g.timestamp = (float)(double.Parse(cols[0].Replace(',', '.'), new CultureInfo("en-US")) - timeZero);
g.gazeX = float.Parse(cols[1].Replace(',', '.'), new CultureInfo("en-US"));
g.gazeY = float.Parse(cols[2].Replace(',', '.'), new CultureInfo("en-US"));
gazes.Add(g);
}
return(gazes);
}
private void initialize(string nameWithoutExtention)
{
paramFilename = nameWithoutExtention + "_param.txt";
filename = nameWithoutExtention + ".csv";
aviOriginal = nameWithoutExtention + ".avi";
pngOriginal = nameWithoutExtention + "_gaze.png";
pngFixations = nameWithoutExtention + "_fixations.png";
aviFixations = nameWithoutExtention + "_fixations.avi";
pngLineBreak = nameWithoutExtention + "_line.png";
aviLineBreak = nameWithoutExtention + "_line.avi";
pngMedian = nameWithoutExtention + "_median.png";
backgroundPath = nameWithoutExtention + "_back.png";
csvFixations = nameWithoutExtention + "_fix.csv";
//Read the data
if (!File.Exists(filename))
{
//Second possibility because of SMi files
filename = filename.Replace(".csv", ".txt");
if (!File.Exists(filename))
{
throw new Exception("Error, the file " + filename + " cannot be found. Press a key to exit the program...");
}
}
List <string> linesTxt = File.ReadAllLines(filename).ToList();
//Inspect the first line, if "Timestamp;GazeX;GazeY;LeftEye;RightEye" it is a Tobii raw data
if (linesTxt[0] == "Timestamp;GazeX;GazeY;LeftEye;RightEye" || linesTxt[0] == "TimeStamp;GazeX;GazeY" || linesTxt[0] == "TimeStamp;GazeX;GazeY;TimeStampWindows")
{
readTobii(linesTxt);
}
else if (linesTxt[0] == "WindowsTime;Timestamp;GazeX;GazeY;PupilDiameter")
{
readTobiiNew(linesTxt);
}
//Else if it is "## [BeGaze]" it is SMi
else if (linesTxt[0] == "## [BeGaze]")
{
readSMiRaw(linesTxt);
}
//Else if the last line is "finish", it is a Fixation file made by the student from SMi
else if (linesTxt[linesTxt.Count - 1] == "finish")
{
int i = 0;
double timeZero = double.Parse(linesTxt[0].Split('\t')[0].Replace(',', '.'), new CultureInfo("en-US"));
while (linesTxt[i] != "blink")
{
string[] cols = linesTxt[i].Split('\t');
Gaze g = new Gaze();
g.timestamp = (float)(double.Parse(cols[0].Replace(',', '.'), new CultureInfo("en-US")) - timeZero);
g.gazeX = float.Parse(cols[2].Replace(',', '.'), new CultureInfo("en-US"));
g.gazeY = float.Parse(cols[3].Replace(',', '.'), new CultureInfo("en-US"));
gazes.Add(g);
i++;
}
}
//a Tobii raw data made by Shoya
else if (linesTxt[0] == "# timestamp,x,y")
{
gazes = readTobiiCsv(linesTxt, ',');
}
//Else exeption
else
{
throw new Exception("Unknown type of input");
}
}
