carla学习笔记(十)

实验室同学需要做仿真数据的采集实验，为记录以下整个采集过程。方便未来进行类似数据采集时减少写代码的时间。

采集数据要求：

控制一辆车，从a点到b点。然后在路侧架设一个lidar，采集车辆通过激光lidar区域时的数据。

一、首先确定a点和b点。

地图选取的是carla的town03。

具体区域是这里：

 首先确定选择的a点：start_point；b点：end_point。

这里使用draw_string函数，将确定的点在地图中显示出来，方便之后的路径确定：

源码如下：

import carla
 
def show_point(world, point_location):
    world.debug.draw_string(point_location, 'X', draw_shadow=False,
                                        color=carla.Color(r=0, g=255, b=0), life_time=50,
                                        persistent_lines=True)
 
def main():
        client = carla.Client('localhost', 2000)
        client.set_timeout(2.0)
        world = client.get_world()
 
        start_point = carla.Location(229, 116, 2)
        end_point = carla.Location(20,194,2)
        show_point(world, start_point)
        show_point(world, end_point)
 
main()

地图显示：

 图中两个绿色的x就是分别确定的start_point和end_point。

这里有几个点需要注意：

1.注意区分carla.Location和carla.Transform之间的关系。

2.注意在使用系统提供的函数的时候，它的参数的格式要求，尤其是spawn_vehicle函数。

怎么才好知道点的坐标呢？

可以使用这个函数测试。首先确定原点，然后确定x轴正向，再确定y轴正向。就可以将地图的坐标系确定出来。好久没有使用carla了，当时在这一步卡了好久，主要原因就是对于相关的函数的数据格式不熟悉了，解决报错问题花了快一个小时。。。

下面是源码：

import carla
 
def show_point(world, point_location):
    world.debug.draw_string(point_location, 'P', draw_shadow=False,
                                        color=carla.Color(r=0, g=255, b=0), life_time=50,
                                        persistent_lines=True)
 
def show_x_point(world, point_location):
    world.debug.draw_string(point_location, 'X', draw_shadow=False,
                                        color=carla.Color(r=0, g=255, b=0), life_time=50,
                                        persistent_lines=True)
 
def show_y_point(world, point_location):
    world.debug.draw_string(point_location, 'Y', draw_shadow=False,
                                        color=carla.Color(r=0, g=255, b=0), life_time=50,
                                        persistent_lines=True)
 
def show_O_point(world, point_location):
    world.debug.draw_string(point_location, 'O', draw_shadow=False,
                                        color=carla.Color(r=0, g=255, b=0), life_time=50,
                                        persistent_lines=True)
 
def main():
        client = carla.Client('localhost', 2000)
        client.set_timeout(2.0)
        world = client.get_world()
        
        start_point = carla.Location(229, 116, 2)
        end_point = carla.Location(20,194,2)
        origin_point = carla.Location(0,0,0)
        x_axis = carla.Location(10, 0, 0)
        y_axis = carla.Location(0, 10, 0)
        show_point(world, start_point)
        show_point(world, end_point)
        show_O_point(world, origin_point)
        show_x_point(world, x_axis)
        show_y_point(world, y_axis)
 
main()

地图显示：

 二、选择lidar点

和第一步类似，使用draw函数来找点。

源码就将上面的简单修改就可以了。

地图显示如下：

 O为架设lidar的坐标。

三、实现vehilce从a点到b点

主要调用的是agent里面的set_destination函数。

参考小飞大佬的源码，自己改了一下：

# -*- coding: utf-8 -*-
 
 
import os
import random
import sys
 
import carla
 
from agents.navigation.behavior_agent import BehaviorAgent
 
 
def main():
    try:
        client = carla.Client('localhost', 2000)
        client.set_timeout(2.0)
 
        world = client.get_world()
 
        origin_settings = world.get_settings()
 
 
        settings = world.get_settings()
        settings.synchronous_mode = True
        settings.fixed_delta_seconds = 0.05
        world.apply_settings(settings)
 
        blueprint_library = world.get_blueprint_library()
 
        # 确定起点和终点
        p1 = carla.Location(229, 116, 2)
        p2 = carla.Location(20, 194, 2)
        start_point = carla.Transform(p1, carla.Rotation(0,0,0))
        end_point = carla.Transform(p2, carla.Rotation(0, 0, 0))
        
        # 创建车辆
        ego_vehicle_bp = blueprint_library.find('vehicle.lincoln.mkz2017')
        ego_vehicle_bp.set_attribute('color', '0, 0, 0')
        vehicle = world.spawn_actor(ego_vehicle_bp, start_point)
 
        world.tick()
 
        # 设置车辆的驾驶模式
        agent = BehaviorAgent(vehicle, behavior='normal')
        # 核心函数
        agent.set_destination(agent.vehicle.get_location(), end_point.location, clean=True)
 
        while True:
            agent.update_information(vehicle)
 
            world.tick()
            
            if len(agent._local_planner.waypoints_queue)<1:
                print('======== Success, Arrivied at Target Point!')
                break
                
            # 设置速度限制
            speed_limit = vehicle.get_speed_limit()
            agent.get_local_planner().set_speed(speed_limit)
 
            control = agent.run_step(debug=True)
            vehicle.apply_control(control)
 
    finally:
        world.apply_settings(origin_settings)
        vehicle.destroy()
 
 
if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        print(' - Exited by user.')

比较简单，看注释就好。

四、生成lidar并采集数据

将生成lidar的部分加入到第三章里面的源码中。

# -*- coding: utf-8 -*-
 
 
import os
import carla
 
from agents.navigation.behavior_agent import BehaviorAgent
 
 
def main():
    try:
        client = carla.Client('localhost', 2000)
        client.set_timeout(2.0)
 
        world = client.get_world()
 
        origin_settings = world.get_settings()
 
 
        settings = world.get_settings()
        settings.synchronous_mode = True
        settings.fixed_delta_seconds = 0.05
        world.apply_settings(settings)
 
        blueprint_library = world.get_blueprint_library()
        # 设置储存位置
        output_path = 'lidar_data'
 
        # 确定起点和终点
        p1 = carla.Location(229, 116, 2)
        p2 = carla.Location(20, 194, 2)
        start_point = carla.Transform(p1, carla.Rotation(0,0,0))
        end_point = carla.Transform(p2, carla.Rotation(0, 0, 0))
        
        # 创建车辆
        ego_vehicle_bp = blueprint_library.find('vehicle.lincoln.mkz2017')
        ego_vehicle_bp.set_attribute('color', '0, 0, 0')
        vehicle = world.spawn_actor(ego_vehicle_bp, start_point)
 
        # 创建lidar，设置lidar的参数
        lidar_bp = blueprint_library.find('sensor.lidar.ray_cast')
        lidar_bp.set_attribute('channels', str(32))
        lidar_bp.set_attribute('points_per_second', str(90000))
        lidar_bp.set_attribute('rotation_frequency', str(40))
        lidar_bp.set_attribute('range', str(20))
        # 设置lidar架设的点
        lidar_location = carla.Location(100, 190, 2)
        lidar_rotation = carla.Rotation(0, 0, 0)
        lidar_transform = carla.Transform(lidar_location, lidar_rotation)        
        # 生成lidar并采集数据
        lidar = world.spawn_actor(lidar_bp, lidar_transform)
        lidar.listen(
            lambda point_cloud: point_cloud.save_to_disk(os.path.join(output_path, '%06d.ply' % point_cloud.frame)))       
 
         
        
        world.tick()
 
        # 设置车辆的驾驶模式
        agent = BehaviorAgent(vehicle, behavior='normal')
        # 核心函数
        agent.set_destination(agent.vehicle.get_location(), end_point.location, clean=True)
 
        while True:
            agent.update_information(vehicle)
 
            world.tick()
            
            if len(agent._local_planner.waypoints_queue)<1:
                print('======== Success, Arrivied at Target Point!')
                break
                
            # 设置速度限制
            speed_limit = vehicle.get_speed_limit()
            agent.get_local_planner().set_speed(speed_limit)
 
            control = agent.run_step(debug=True)
            vehicle.apply_control(control)
 
    finally:
        world.apply_settings(origin_settings)
        vehicle.destroy()
 
 
if __name__ == '__main__':
    try:
        main()
    except KeyboardInterrupt:
        print(' - Exited by user.')

比较简单，整个实验采集都比较简单。在这里记录一下，方便未来做类似工作是可以直接代码服用。