Package edu.wpi.first.apriltag

Class AprilTagPoseEstimator

java.lang.Object
edu.wpi.first.apriltag.AprilTagPoseEstimator
public class AprilTagPoseEstimator
extends Object
Pose estimators for AprilTag tags.

  • Constructor Details

  • Method Details

    • setConfig

      public void setConfig​(AprilTagPoseEstimator.Config config)
      Sets estimator configuration.
      Parameters:
      config - Configuration

    • getConfig

      public AprilTagPoseEstimator.Config getConfig()
      Gets estimator configuration.
      Returns:
      Configuration

    • estimateHomography

      public Transform3d estimateHomography​(AprilTagDetection detection)
      Estimates the pose of the tag using the homography method described in [1].
      Parameters:
      detection - Tag detection
      Returns:
      Pose estimate

    • estimateHomography

      public Transform3d estimateHomography​(double[] homography)
      Estimates the pose of the tag using the homography method described in [1].
      Parameters:
      homography - Homography 3x3 matrix data
      Returns:
      Pose estimate

    • estimateOrthogonalIteration

      public AprilTagPoseEstimate estimateOrthogonalIteration​(AprilTagDetection detection, int nIters)
      Estimates the pose of the tag. This returns one or two possible poses for the tag, along with the object-space error of each.

      This uses the homography method described in [1] for the initial estimate. Then Orthogonal Iteration [2] is used to refine this estimate. Then [3] is used to find a potential second local minima and Orthogonal Iteration is used to refine this second estimate.

      [1]: E. Olson, “Apriltag: A robust and flexible visual fiducial system,” in 2011 IEEE International Conference on Robotics and Automation, May 2011, pp. 3400–3407.

      [2]: Lu, G. D. Hager and E. Mjolsness, "Fast and globally convergent pose estimation from video images," in IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 22, no. 6, pp. 610-622, June 2000. doi: 10.1109/34.862199

      [3]: Schweighofer and A. Pinz, "Robust Pose Estimation from a Planar Target," in IEEE Transactions on Pattern Analysis and Machine Intelligence, vol. 28, no. 12, pp. 2024-2030, Dec. 2006. doi: 10.1109/TPAMI.2006.252

      Parameters:
      detection - Tag detection
      nIters - Number of iterations
      Returns:
      Initial and (possibly) second pose estimates

    • estimateOrthogonalIteration

      public AprilTagPoseEstimate estimateOrthogonalIteration​(double[] homography, double[] corners, int nIters)
      Estimates the pose of the tag. This returns one or two possible poses for the tag, along with the object-space error of each.
      Parameters:
      homography - Homography 3x3 matrix data
      corners - Corner point array (X and Y for each corner in order)
      nIters - Number of iterations
      Returns:
      Initial and (possibly) second pose estimates

    • estimate

      public Transform3d estimate​(AprilTagDetection detection)
      Estimates tag pose. This method is an easier to use interface to EstimatePoseOrthogonalIteration(), running 50 iterations and returning the pose with the lower object-space error.
      Parameters:
      detection - Tag detection
      Returns:
      Pose estimate

    • estimate

      public Transform3d estimate​(double[] homography, double[] corners)
      Estimates tag pose. This method is an easier to use interface to EstimatePoseOrthogonalIteration(), running 50 iterations and returning the pose with the lower object-space error.
      Parameters:
      homography - Homography 3x3 matrix data
      corners - Corner point array (X and Y for each corner in order)
      Returns:
      Pose estimate