image_geometry project3d to pixel

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I'm getting multiple projections of 3d points to the same pixel which don't coincide with the 3D ray but parallel with the image plane. This can be seen here:

I'm unable to find an error in my code or in the re-projection function (CODE API)

This is my code fragment in which I calculate it:

void calculateVoxels (void)
{
 Point2d uv;
 Point3d pt_cv;
 int width, height;
 double vox_number = 0;

 width = cam_model_.reducedResolution().width;
 height = cam_model_.reducedResolution().height;

 cloud_.width    = WORLD_RESOLUTION;
 cloud_.height   = 1;
 cloud_.is_dense = false;
 cloud_.points.resize (WORLD_RESOLUTION);
 ///Only calculate if the image and the camera info are received.
 if(image_rec_ & cam_info_rec_){
 double x, y , z;
 int a=0;
 int b=0;
 int c=0;
 for(x = WORLD_BEGIN_X; x < WORLD_MAX_X; a++){
  b = 0;
  for(y = WORLD_BEGIN_Y; y < WORLD_MAX_Y; b++){
    c = 0;
    for(z = WORLD_BEGIN_Z; z < WORLD_MAX_Z; c++){
      pt_cv = Point3d(x, y, z);

      ///WARNING!: (u,v) in rectified pixel coordinates!
      uv = cam_model_.project3dToPixel(pt_cv);

      ///@todo : check this, might be inverse
      ///Only if it falls on the image plane
      if((uv.x < height) && (uv.y < width) && (uv.x >=0) && (uv.y >= 0)){

        if(current_image_.at<int>(uv) != 0){
          world_[a][b][c] = 255;           ///Start indexing from 0,0,0 in the array!

          ///Also create the pointcloud
          cloud_.points[vox_number].x = x;
          cloud_.points[vox_number].y = y;
          cloud_.points[vox_number].z = z;
          vox_number ++;
        }
        else
          world_[a][b][c] = 0;
      }
      z= z + WORLD_STEP_Z;
    }
    y= y + WORLD_STEP_Y;
  }
  x= x + WORLD_STEP_X;
}

calc_voxels_ = true; 
///Trigger a update of the OpenGL world
if(do_opengl_){
  glutPostRedisplay();
}

///Save the pointcloud
cloud_.width = vox_number;            ///minimize the size of the pointcloud
cloud_.points.resize (vox_number);    ///maximal  vox_number points written
if(save_cloud_){
  pcl::io::savePCDFileASCII (PCL_PCD_SAVE, cloud_);
  ROS_INFO ("Saved %d data points to %s", (int)cloud_.points.size (), PCL_PCD_SAVE);
}

cloud_.header.frame_id = "world";
cloud_.header.stamp = ros::Time::now ();
pub_.publish(cloud_);

}
}