Why the annotated keypoints are sometimes very small or huge?

[futakw]

https://github.com/google-research-datasets/Objectron/blob/c06a65165a18396e1e00091981fd1652875c97b5/objectron/dataset/graphics.py#L34-L40

As described here, I think the "keypoints.point_2d.x" or "keypoints.point_2d.y" should be in the range of 0 to 1 if x/y are inside the image. However, I observe that sometimes those are extremely small or huge.

For example, "~/bike/batch-11/5/annotation.pbdata" has

keypoints {                                                                                                                                                                                               
    id: 2                                                                                                                                                                                                   
    point_3d {                                                                                                                                                                                              
      x: 1.2235139608383179                                                                                                                                                                                 
      y: 1.1318135261535645                                                                                                                                                                                 
      z: 0.07509636878967285                                                                                                                                                                                
    }                                                                                                                                                                                                       
    point_2d {                                                                                                                                                                                              
      x: -15.717081069946289                                                                                                                                                                                
      y: -12.666918754577637                                                                                                                                                                                
      depth: -0.07509636878967285                                                                                                                                                                           
    }                                                                                                                                                                                                       
  }  

with extremely small x and y.

[ahmadyan]

You can discard the point when the depth is negative (i.e. the point is behind the camera).