邻域搜索，半径内没有点时，程序报错

y235315

利用PCL 的KDtree进行邻域搜索的时候，当半径内没有点时，程序会报错：<vector subscript out of range>
代码如下：
pcl::PointCloud<pcl::PointXYZ>::Ptr cloud (new
pcl::PointCloud<pcl::PointXYZ>);

  // Generate pointcloud data
  cloud->width = 1000;
  cloud->height = 1;
  cloud->points.resize (cloud->width * cloud->height);

  for (size_t i = 0; i < cloud->points.size (); ++i)
  {
    cloud->points.x = 1024.0f * rand () / (RAND_MAX + 1.0f);
    cloud->points.y = 1024.0f * rand () / (RAND_MAX + 1.0f);
    cloud->points.z = 1024.0f * rand () / (RAND_MAX + 1.0f);
  }

  pcl::KdTreeFLANN<pcl::PointXYZ> kdtree;

  kdtree.setInputCloud (cloud);

  pcl::PointXYZ searchPoint;

  searchPoint.x = 0;
  searchPoint.y = 0;
  searchPoint.z = 0;

// Neighbors within radius search

  std::vector<int> pointIdxRadiusSearch;
  std::vector<float> pointRadiusSquaredDistance;

  float radius = 1.0;

  if ( kdtree.radiusSearch (searchPoint, radius, pointIdxRadiusSearch,
pointRadiusSquaredDistance) > 0 )
  {
  }

请问是什么原因，该如何解决？