Retaining wall boundary extraction

Extract retaining wall boundaries based on point clouds

Algorithm ideas

1. Transfer the point to the polar coordinate system, get the index value in the polar coordinate system, and output the distance information.

double getCellIndexFromPoints(double x, double y, int& chI)
{
    
    
    // 计算点到原点的欧几里得距离
    double distance = sqrt(x * x + y * y);

    // 将极坐标中的角度映射为一个标准化的值，确保在 [0, 1) 范围内
    double chP = (atan2(y, x) + M_PI) / (2 * M_PI);

    // 将标准化的角度值映射为索引值（在 numChannel_ 范围内）
    chI = floor(chP * numChannel_);

    // 返回点到原点的欧几里得距离
    return distance;
}

2. Define a grid Cell, which stores x, y coordinates and distance. Define a map, key is the index, and value is the raster. When the indexes are the same, the distance of the grid is judged, and the small distance is retained.

typedef  struct
{
    
    
    double x,y;
    double distance = 9999;
}Cell;

    cell_map.clear();
    for(auto point : cloud->points){
    
    
        int chI = -1;
        double distance = getCellIndexFromPoints(point.x,point.y,chI);
        if (chI >= 0 && chI < numChannel_){
    
    
            if(cell_map.find(chI)==cell_map.end() || cell_map[chI].distance > distance){
    
    
                cell_map[chI] = {
    
    point.x,point.y,distance};
            }
        }
    }

3. Traverse the map, fill in the x and y in Value into the boundary line, and get the final content

    for(auto map_item : cell_map){
    
    
        PointSany point{
    
    map_item.second.x,map_item.second.y,1.0};
        hull->points.push_back(point);
    }