cartographer_ros 命令行参数解析和日志打印

/*
 * Copyright 2016 The Cartographer Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include "absl/memory/memory.h"
#include "cartographer/mapping/map_builder.h"
#include "cartographer_ros/node.h"
#include "cartographer_ros/node_options.h"
#include "cartographer_ros/ros_log_sink.h"
#include "gflags/gflags.h"
#include "tf2_ros/transform_listener.h"

DEFINE_bool(collect_metrics, false,
            "Activates the collection of runtime metrics. If activated, the "
            "metrics can be accessed via a ROS service.");
DEFINE_string(configuration_directory, "",
              "First directory in which configuration files are searched, "
              "second is always the Cartographer installation to allow "
              "including files from there.");
DEFINE_string(configuration_basename, "",
              "Basename, i.e. not containing any directory prefix, of the "
              "configuration file.");
DEFINE_string(load_state_filename, "",
              "If non-empty, filename of a .pbstream file to load, containing "
              "a saved SLAM state.");
DEFINE_bool(load_frozen_sta