Posit Class
3D pose estimation algorithm.

Namespace:  AForge.Math.Geometry
Assembly:  AForge.Math (in AForge.Math.dll) Version: 2.2.5.0 (2.2.5.0)

Syntax

C#
public class Posit

Remarks

The class implements an algorithm for 3D object's pose estimation from it's 2D coordinates obtained by perspective projection, when the object is described none coplanar points. The idea of the implemented math and algorithm is described in "Model-Based Object Pose in 25 Lines of Code" paper written by Daniel F. DeMenthon and Larry S. Davis (the implementation of the algorithm is almost 1 to 1 translation of the pseudo code given by the paper, so should be easy to follow).

Note:At this point the implementation works only with models described by 4 points, which is the minimum number of points enough for 3D pose estimation.

Note:The 4 model's point must not be coplanar, i.e. must not reside all within same planer. See CoplanarPosit for coplanar case.

Read 3D Pose Estimation article for additional information and samples.

Sample usage:

CopyC#
// points of real object - model
Vector3[] positObject = new Vector3[4]
{ 
    new Vector3(  28,  28, -28 ),
    new Vector3( -28,  28, -28 ),
    new Vector3(  28, -28, -28 ),
    new Vector3(  28,  28,  28 ),
};
// focal length of camera used to capture the object
float focalLength = 640; // depends on your camera or projection system
// initialize POSIT object
Posit posit = new Posit( positObject, focalLength );

// 2D points of te object - projection
AForge.Point[] projectedPoints = new AForge.Point[4]
{
    new AForge.Point(   -4,   29 ),
    new AForge.Point( -180,   86 ),
    new AForge.Point(   -5, -102 ),
    new AForge.Point(   76,  137 ),
};
// estimate pose
Matrix3x3 rotationMatrix;
Vector3 translationVector;
posit.EstimatePose( projectedPoints,
    out rotationMatrix, out translationVector );

Inheritance Hierarchy

System..::.Object
  AForge.Math.Geometry..::.Posit

See Also