概述：cartographer的地图由许多个submap构成，每个submap又由许多个Node构成，而每个Node是由一帧或多帧激光数据累积得到。
-- 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.
TRAJECTORY_BUILDER_2D = {
use_imu_data = true, --是否使用imu数据
min_range = 0., --激光的最近距离
max_range = 30., --激光的最远距离
min_z = -0.8, --激光的最小高度
max_z = 2., --激光的最大高度
missing_data_ray_length = 5., --如果不在min_range和max_range之间，则默认给这个数值
num_accumulated_range_data = 1, --积累几帧激光数据作为一个Node节点
voxel_filter_size = 0.025, --一帧激光的网格滤波大小，单位为米。
adaptive_voxel_filter = {
--自适应滤波，就是自适应调整滤波网格的大小、使得点云数量刚刚好大于最小点云数量，同时又不过多。
max_length = 0.5, -- 初始网格滤波的大小，单位为米
min_num_points = 200, --最小点云数据
max_range = 50., --点云的最远距离
},
loop_closure_adaptive_voxel_filter = {
--闭环检测自适应滤波
max_length = 0.9, --同上
min_num_points = 100, --同上
max_range = 50., --同上
},
use_online_correlative_scan_matching = false, --使用CSM激光匹配
real_time_correlative_scan_matcher = {
--快速CSN激光匹配
linear_search_window = 0.1, --平移搜索范围
angular_search_window = math.rad(20.), --角度搜索范围
translation_delta_cost_weight = 1e-1, --平移代价权重，就是距离初始值越远，匹配得分要越高才能被信任
rotation_delta_cost_weight = 1e-1, --旋转代价权重，同上
},
ceres_scan_matcher = {
--使用ceres优化的方式进行激光匹配
occupied_space_weight = 1., --占据空间权重
translation_weight = 10., --平移权重
rotation_weight = 40., --旋转权重
ceres_solver_options = {
--ceres优化参数
use_nonmonotonic_steps = false, --使用非单调的步骤，这个功能再明确一下
max_num_iterations = 20, --最大迭代次数
num_threads = 1, --使用几个线程优化
},
},
motion_filter = {
--移动滤波，就是判断小车有没有动，就是检测2帧激光数据是否相似，要满足一下全部条件
max_time_seconds = 5., --2帧激光时间戳小间隔
max_distance_meters = 0.2, --2帧激光最小距离
max_angle_radians = math.rad(1.), --2帧激光最小角度
},
-- TODO(schwoere,wohe): Remove this constant. This is only kept for ROS.
imu_gravity_time_constant = 10., --imu的重力常数
pose_extrapolator = {
--位姿推断
use_imu_based = false, --3d用来初始化位姿推断器的方式
constant_velocity = {
imu_gravity_time_constant = 10., --imu的重力常数
pose_queue_duration = 0.001,
},
imu_based = {
--这个还不清楚
pose_queue_duration = 5.,
gravity_constant = 9.806,
pose_translation_weight = 1.,
pose_rotation_weight = 1.,
imu_acceleration_weight = 1.,
imu_rotation_weight = 1.,
odometry_translation_weight = 1.,
odometry_rotation_weight = 1.,
solver_options = {
use_nonmonotonic_steps = false;
max_num_iterations = 10;
num_threads = 1;
},
},
},
submaps = {
--子图
num_range_data = 90, --子图中Node的数量
grid_options_2d = {
grid_type = "PROBABILITY_GRID", --概率栅格地图
resolution = 0.05, --分辨率
},
range_data_inserter = {
range_data_inserter_type = "PROBABILITY_GRID_INSERTER_2D",
probability_grid_range_data_inserter = {
insert_free_space = true,
hit_probability = 0.55,
miss_probability = 0.49,
},
tsdf_range_data_inserter = {
truncation_distance = 0.3,
maximum_weight = 10.,
update_free_space = false,
normal_estimation_options = {
num_normal_samples = 4,
sample_radius = 0.5,
},
project_sdf_distance_to_scan_normal = true,
update_weight_range_exponent = 0,
update_weight_angle_scan_normal_to_ray_kernel_bandwidth = 0.5,
update_weight_distance_cell_to_hit_kernel_bandwidth = 0.5,
},
},
},
}
居然还有一些参数不能明白，看来距离返攻cartographer的时间又要延长了