关于src/preprocess.cpp中源码的疑惑与config参数的疑惑

[ZRS0326]

🕛在src/preprocess.cpp 90～98行代码中的if语句，请问这段代码的作用是什么？
**if((abs(msg->points[i].x - msg->points[i-1].x) < 1e-8) 
        || (abs(msg->points[i].y - msg->points[i-1].y) < 1e-8)
        || (abs(msg->points[i].z - msg->points[i-1].z) < 1e-8)
        || (msg->points[i].x * msg->points[i].x + msg->points[i].y * msg->points[i].y < blind)
        || (msg->points[i].line > N_SCANS)
        || ((msg->points[i].tag & 0x30) != RETURN0AND1))
    {
        continue;
    }**
🕛在config中关于相机的以下参数作用是什么？

cam_d0: -0.0944205499243979 cam_d1: 0.0946727677776504 cam_d2: -0.00807970960613932 cam_d3: 8.07461209775283e-05

[xuankuzcr]

1. 这些条件分别是： 与上一个点在x、y、z坐标轴上的差值小于1e-8 点的x和y坐标的平方和小于"blind"（一个预设的阈值）去除较近点 点的线数（line）大于N_SCANS（一个预设的常量） 点的tag属性的第5位和第6位不是RETURN0AND1（一个预设的常量）只要0和1回波的点
2. 代表针孔相机的畸变参数

[Camilochiang]

Actually this conditions produce some problems:

• When using a mid70 (that have a special minimum range of 0.05 m) and passing close to an object , all points get rejected by the condition ((msg->points[i].tag` & 0x30) != RETURN0AND1)
• When using different lidars the blind parameter have different meanings what is confusing and lack standarization.

I change the above condition to this one and it work better (faster and more points in my PCL)

 double range = pl_orig.points[i].x * pl_orig.points[i].x + pl_orig.points[i].y * pl_orig.points[i].y + pl_orig.points[i].z * pl_orig.points[i].z;
 if (range < blind) || (msg->points[i].line > N_SCANS) {
    continue;
}