# Vision Odometry ## What is Vision Odometry? Vision odometry data is normally added by using [`SwerveDrivePoseEstimator.addVisionMeasurement`](https://github.wpilib.org/allwpilib/docs/release/java/edu/wpi/first/math/estimator/PoseEstimator.html#addVisionMeasurement\(edu.wpi.first.math.geometry.Pose2d,double,edu.wpi.first.math.Matrix\)) and since YAGSL handles [`SwerveDrivePoseEstimator`](https://github.wpilib.org/allwpilib/docs/release/java/edu/wpi/first/math/estimator/SwerveDrivePoseEstimator.html) for you we extend the functions inside of [`SwerveDrive`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveDrive.html) to handle vision measurements with [`SwerveDrive.addVisionMeasurement`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveDrive.html#addVisionMeasurement\(edu.wpi.first.math.geometry.Pose2d,double\)) instead of creating your own estimator. ## How do I use Vision Odometry? There is an example usage in YAGSL-Example where we show a dummy usecase while using fake vision measurements. Effectively you would use the [`SwerveDrive`](https://yet-another-software-suite.github.io/YAGSL/javadocs/swervelib/SwerveDrive.html) class as the pose estimator. 
/**
 * Add a fake vision reading for testing purposes.
 */
public void addFakeVisionReading()
{
  swerveDrive.addVisionMeasurement(new Pose2d(3, 3, Rotation2d.fromDegrees(65)), Timer.getFPGATimestamp());
}