描述

Run()函数中的记载配置参数的代码解析

node_main.cc中的Run()函数中有这样一段核心代码

NodeOptions node_options;
TrajectoryOptions trajectory_options;
std::tie(node_options, trajectory_options) =
    LoadOptions(FLAGS_configuration_directory, FLAGS_configuration_basename);

auto map_builder =
    cartographer::mapping::CreateMapBuilder(node_options.map_builder_options);
Node node(node_options, std::move(map_builder), &tf_buffer,
          FLAGS_collect_metrics);
if (!FLAGS_load_state_filename.empty()) {
  node.LoadState(FLAGS_load_state_filename, FLAGS_load_frozen_state);
}

if (FLAGS_start_trajectory_with_default_topics) {
  node.StartTrajectoryWithDefaultTopics(trajectory_options);
}

这段代码中的以下语句是什么含义呢，加载配置文件

std::tie(node_options, trajectory_options) =
    LoadOptions(FLAGS_configuration_directory, FLAGS_configuration_basename);

加载配置文件

node_main.cc中的Run()函数中

NodeOptions node_options;
TrajectoryOptions trajectory_options;
std::tie(node_options, trajectory_options) =
    LoadOptions(FLAGS_configuration_directory, FLAGS_configuration_basename);

LoadOptions()函数声明在cartographer_ros/node_option.h中，在node_option.cc的源文件里写着实现内容

std::tuple<NodeOptions, TrajectoryOptions> LoadOptions(
    const std::string& configuration_directory,
    const std::string& configuration_basename) {
  auto file_resolver =
      absl::make_unique<cartographer::common::ConfigurationFileResolver>(
          std::vector<std::string>{configuration_directory});
  const std::string code =
      file_resolver->GetFileContentOrDie(configuration_basename);
  cartographer::common::LuaParameterDictionary lua_parameter_dictionary(
      code, std::move(file_resolver));

  return std::make_tuple(CreateNodeOptions(&lua_parameter_dictionary),
                         CreateTrajectoryOptions(&lua_parameter_dictionary));
}

函数中的

configuration_directory是字符串$(find cartographer_ros)/configuration_files
configuration_basename是字符串backpack_2d.lua

显然，他们是我们建图时的参数文件，该函数返回的NodeOptions和TrajectoryOptions其实就是两个struct，分别声明在node_options.h和trajectory_options.h中

  • 读取NodeOptions
    定义在cartographer_ros/node_options.cc中
CreateNodeOptions(&lua_parameter_dictionary)

读取的参数包括

map_builder = MAP_BUILDER,
map_frame = "map",
lookup_transform_timeout_sec = 0.2,
submap_publish_period_sec = 0.3,
pose_publish_period_sec = 5e-3,
trajectory_publish_period_sec = 30e-3,
use_pose_extrapolator = true

还有两个参数是backpack_2d.lua文件中没有的，publish_to_tf和publish_tracked_pose

  • 读取TrajectoryOptions

定义在cartographer_ros/tracjectory_options.cc中

CreateTrajectoryOptions(&lua_parameter_dictionary)

读取的参数包括

trajectory_builder = TRAJECTORY_BUILDER,
tracking_frame = "base_link",
published_frame = "base_link",
odom_frame = "odom",
provide_odom_frame = true,
use_odometry = false,
use_nav_sat = false,
use_landmarks = false,
publish_frame_projected_to_2d = false,
num_laser_scans = 0,
num_multi_echo_laser_scans = 1,
num_subdivisions_per_laser_scan = 10,
num_point_clouds = 0,
rangefinder_sampling_ratio = 1.,
odometry_sampling_ratio = 1.,
fixed_frame_pose_sampling_ratio = 1.,
imu_sampling_ratio = 1.,
landmarks_sampling_ratio = 1.,

两者加一起一共25项参数，backpack_2d.lua也只有25项参数，也就是说， CreateNodeOptions和CreateTrajectoryOptions刚好读取了参数文件中的全部配置项