Day3

Day 3 Wednesday June 23 2004

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  We have acquired a new version of the code. This one has a workaround for the
  imview problem. We are about to test it.

  The code works. We are speculating on solutions for our problem:

  Currently discussing:

• Calibrating the camera so that it looks exactly in the centre of the board at the angle we decide.
  • We can put colored stickers on the corners of the board so that we can calibrate the camera.

  We're working out this idea first.

• First of all we shall put four stickers of different coulours on the corners of the board.
• We shall name them from left to right, top to bottom: A,B,C,D (from the perspective of AIBO)
• We assume that aibo is already elevated to a certain level and is seeing all the four points.

  Here is our pseudocode for calibration:

 While ((Ay != By || Cy != Dy) || (abs(Bx-Dx) != abs(Ax-Cx))) (we appoint a precision margin)

  1. If By > Ay rotate clockwise (negative) While By > Ay (we appoint a precision margin)
     Else If By < Ay rotate counter clockwise (positive) While By < Ay (we appoint a precision margin)

  2. If Bx > Dx translate left upon x-axis (negative) While Bx > Dx (we appoint a precision margin)
     Else If Ax < Cx translate right upon x-axis (positive) While Ax < Cx (we appoint a precision margin)

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 We are now speculating on how to project the cartesian location of a poin on the 2d camera image, upon the
 3d cartesian location of the chessboard. 

 For this we need:

• Rotate the 2d image on the x-axis negatively over the (invTan(aibohead height/aibohead to centre of board distance))
• Than translate the 2d image over the camera viewing direction (Tz = - aibohead height Ty = - aibohead to centre of board distance)

 We shall attempt to make a projection matrix for this.

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  Partial implementation of the projection algorithm:

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 //Has? the ability to project a 2d camera coordinate upon board.

 public class CameraPoint?
 {
  double xcam,
      ycam,
      ycampos = 0, //set distance from zero point of the camera manually
      xcampos = 0, //must remain zero since the camera is looking directly through the middle of the board
      zcampos = 0, //set height of the camera manually
      ycamdist, //y coordinate of aibocam - y coordinate of the middle of the board
      zcamdist, //height of aibocam - height of board
      xchess,
      ychess;

  String chesspos = "";

  double camangle,    //the angle between the camera viewing direction and the normal of the board
         f = 0;        //aibocam focuspoint.

  ChessBoard? b;

  public CameraPoint?(int xcam, int ycam, ChessBoard? board)
  {
    this.xcam = xcam;
    this.ycam = ycam;
    b = board;

    ycamdist =  ycampos - (b.coords.y+b.sur_y+b.delta_y*4);
    zcamdist = zcampos - b.coords.z;
    camangle = Math.atan(ycamdist/zcamdist);
  }

  public void projectToChess?()
  {
    //first we rotate around x-axis of the board in the positive direction
    //than we translate to the chessboard
    double[][] projection = {{1,            0,                    0,                0},
                             {0, Math.cos(camangle), - Math.sin(camangle), - ycamdist},
			     {0, Math.sin(camangle),   Math.cos(camangle), - zcamdist},
			     {0,            0,                    0,                1}};

     xchess = xcam;
     ychess = ycam*projection[1][1] + projection[1][3];

     char column = (char)('h' - (b.coords.x - xchess - b.sur_x)/(double)b.delta_x); //amount of squares from h to a on the board
     char row = (char)('8' -(ychess - b.coords.y - b.sur_y)/(double)b.delta_y);     
     chesspos = chesspos + column + row;
  }
 }

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partial implementation of the calibration algorithm:

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 // calibration.java probeerd het midden van het bord recht voor de aibo te leggen.
 // author: 	marc bron & aziz baibabaev 
 // cknr:	0130486 & 0222704

 import tio.*;

 public class Calibration
 {

 private point A;
 private point B;
 private point C;
 private point D;

 public void Calibration(point A, point B, point C, point D)
 {

  A = this.A;
  B = this.B;
  C = this.C;
  D = this.D;

 }
 public void doCalibration()
 {
   While ( (A.y != B.y || C.y != D.y) || ( Math.abs(B.x - D.x) != Math.abs(A.x - C.x) ) )
   {
    System.out.println(" rotate ")

    if(B.y > A.y)
      System.out.println(" rotate clockwise ");
    else if (B.y < A.y)
      System.out.println(" rotate counter clockwise ");

    System.out.println(" translate ");

    if(B.x > D.x)
      System.out.println(" translate left upon x-axis ");
    else if (A.x < C.x)
      System.out.println(" translate right upon x-axis ");

   }
 }

 }

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End of Day 3