I am using the simpleOpenni library in order to retrieve the point cloud from a Kinect. Then I take three random real world points and I calculate the parameters of the plane equations on me own  using this method from this site:  http://www.had2know.com/academics/equation-plane-through-3-points.html (Actually I use Matlab for the calculations). Afterwards I put every real world point form the point cloud to the equation hoping that I took a result close to zero...The problem is that I obtain very large number instead....Can you help me please?

2. import SimpleOpenNI.*;
3. 
   
4. SimpleOpenNI context;
5. float        zoomF =0.3f;
6. float        rotX = radians(180);  // by default rotate the hole scene 180deg around the x-axis, 
7.                                    // the data from openni comes upside down
8. float        rotY = radians(0);
9. int     index;
10. PVector [] p=new PVector [304635];
11. 
    
12. 
    
13. void setup()
14. {
15.    frameRate(300);
16.  
17.   size(640,480,P3D);  // strange, get drawing error in the cameraFrustum if i use P3D, in opengl there is no problem
18. 
    
19.   //context = new SimpleOpenNI(this,SimpleOpenNI.RUN_MODE_SINGLE_THREADED);
20.   context = new SimpleOpenNI(this);
21. 
    
22.   // disable mirror
23.   context.setMirror(false);
24. 
    
25.   // enable depthMap generation 
26.   if(context.enableDepth() == false)
27.   {
28.      println("Can't open the depthMap, maybe the camera is not connected!"); 
29.      exit();
30.      return;
31.   }
32. 
    
33.   stroke(255,255,255);
34.   smooth();
35.   perspective(radians(45),
36.               float(width)/float(height),
37.               10,150000);
38. }
39. 
    
40. void draw()
41. {
42.   // update the cam
43.   context.update();
44. 
    
45.   background(0,0,0);
46. 
    
47.   translate(width/2, height/2, 0);
48.   rotateX(rotX);
49.   rotateY(rotY);
50.   scale(zoomF);
51. 
    
52.   int[]   depthMap = context.depthMap();
53.   int     steps   =10;  // to speed up the drawing, draw every third point
54.   
55.   PVector realWorldPoint;
56.   
57.   int z=0;
58.  
59.   translate(0,0,-1000);  // set the rotation center of the scene 1000 infront of the camera
60. 
    
61.   stroke(255);
62. 
    
63.   PVector[] realWorldMap = context.depthMapRealWorld();
64.   for(int y=80;y < context.depthHeight();y+=steps)
65.   {
66.     for(int x=0;x < context.depthWidth();x+=steps)
67.     {
68.       index = x + y * context.depthWidth();
69.       
70.       
71.       
72.       
73.       if(depthMap[index] > 0)
74.       { 
75.         // draw the projected point
76. //        realWorldPoint = context.depthMapRealWorld()[index];
77.         realWorldPoint = realWorldMap[index];
78.         stroke(240,240,240);//grey
79.         point(realWorldPoint.x,realWorldPoint.y,realWorldPoint.z);  // make realworld z negative, in the 3d drawing coordsystem +z points in the direction of the eye       
80.         
81.         
82.       /*  realWorldPoint = realWorldMap[300 + 450 * context.depthWidth()];
83.         stroke(95,158,160);
84.         point(realWorldPoint.x,realWorldPoint.y,realWorldPoint.z);
85.         println(realWorldPoint.x+","+realWorldPoint.y+","+realWorldPoint.z);
86.        */ 
87.        double plane=( 9.5721e+03*realWorldPoint.z)- ( 3.8451e+04*realWorldPoint.y) -  (1.3451e+03*realWorldPoint.x) -  1.6337e+07;
88.   
89.  println(plane);
90.   
91. if(plane==0){
92.   stroke(95,158,160);  //blue  
93.   point(realWorldPoint.x,realWorldPoint.y,realWorldPoint.z);
94.  }
95.     }
96.   } 
97. 
    
98.   // draw the kinect cam
99.  // context.drawCamFrustum();
100. 
     
101. }
102. 
     
103. /*PVector v1=new PVector(0,0,0);
104. 
     
105. 
     
106. for (int i=0; i<16; i++){
107.   
108. v1=p[i];
109. 
     
110. println(v1);
111. */
112. 
     
113. 
     
114.  noLoop();
115. }
116. 
     
117. 
     
118. void keyPressed()
119. {
120.   switch(key)
121.   {
122.   case ' ':
123.     context.setMirror(!context.mirror());
124.     break;
125.   }
126. 
     
127.   switch(keyCode)
128.   {
129.   case LEFT:
130.     rotY += 0.1f;
131.     break;
132.   case RIGHT:
133.     // zoom out
134.     rotY -= 0.1f;
135.     break;
136.   case UP:
137.     if(keyEvent.isShiftDown())
138.       zoomF += 0.02f;
139.     else
140.       rotX += 0.1f;
141.     break;
142.   case DOWN:
143.     if(keyEvent.isShiftDown())
144.     {
145.       zoomF -= 0.02f;
146.       if(zoomF < 0.01)
147.         zoomF = 0.01;
148.     }
149.     else
150.       rotX -= 0.1f;
151.     break;
152.   }
153. }
 

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