pointcloud_to_laserscan:将3D点云转换为2D激光扫描

# ROS 2 pointcloud <-> laserscan converters This is a ROS 2 package that provides components to convert `sensor_msgs/msg/PointCloud2` messages to `sensor_msgs/msg/LaserScan` messages and back. It is essentially a port of the original ROS 1 package. ## pointcloud\_to\_laserscan::PointCloudToLaserScanNode This ROS 2 component projects `sensor_msgs/msg/PointCloud2` messages into `sensor_msgs/msg/LaserScan` messages. ### Published Topics * `scan` (`sensor_msgs/msg/LaserScan`) - The output laser scan. ### Subscribed Topics * `cloud_in` (`sensor_msgs/msg/PointCloud2`) - The input point cloud. No input will be processed if there isn't at least one subscriber to the `scan` topic. ### Parameters * `min_height` (double, default: 0.0) - The minimum height to sample in the point cloud in meters. * `max_height` (double, default: 1.0) - The maximum height to sample in the point cloud in meters. * `angle_min` (double, default: -π/2) - The minimum scan angle in radians. * `angle_max` (double, default: π/2) - The maximum scan angle in radians. * `angle_increment` (double, default: π/360) - Resolution of laser scan in radians per ray. * `queue_size` (double, default: detected number of cores) - Input point cloud queue size. * `scan_time` (double, default: 1.0/30.0) - The scan rate in seconds. Only used to populate the scan_time field of the output laser scan message. * `range_min` (double, default: 0.45) - The minimum ranges to return in meters. * `range_max` (double, default: 4.0) - The maximum ranges to return in meters. * `target_frame` (str, default: none) - If provided, transform the pointcloud into this frame before converting to a laser scan. Otherwise, laser scan will be generated in the same frame as the input point cloud. * `transform_tolerance` (double, default: 0.01) - Time tolerance for transform lookups. Only used if a `target_frame` is provided. * `use_inf` (boolean, default: true) - If disabled, report infinite range (no obstacle) as range_max + 1. Otherwise report infinite range as +inf. ## pointcloud\_to\_laserscan::LaserScanToPointCloudNode This ROS 2 component re-publishes `sensor_msgs/msg/LaserScan` messages as `sensor_msgs/msg/PointCloud2` messages. ### Published Topics * `cloud` (`sensor_msgs/msg/PointCloud2`) - The output point cloud. ### Subscribed Topics * `scan_in` (`sensor_msgs/msg/LaserScan`) - The input laser scan. No input will be processed if there isn't at least one subscriber to the `cloud` topic. ### Parameters * `queue_size` (double, default: detected number of cores) - Input laser scan queue size. * `target_frame` (str, default: none) - If provided, transform the pointcloud into this frame before converting to a laser scan. Otherwise, laser scan will be generated in the same frame as the input point cloud. * `transform_tolerance` (double, default: 0.01) - Time tolerance for transform lookups. Only used if a `target_frame` is provided. * `use_inf` (boolean, default: true) - If disabled, report infinite range (no obstacle) as range_max + 1. Otherwise report infinite range as +inf.