ROSIntegration ROSIntegrationVision与虚幻引擎4（Unreal Engine 4）的配置

操作系统：Ubuntu 18.04

虚幻引擎：4.26.2

一、虚幻引擎源代码下载与编译运行

参照官方文档：虚幻引擎Linux快速入门

二、ROSIntegration下载与配置运行

1、配置ROSBridge

要启用虚幻和ROS之间的通信，需要一个正在运行的ROSBridge和bson_mode

注意：请使用 rosbridge 版本=>0.8.0 以获得完整的 BSON 支持

安装rosbridge的推荐方法是在ROS工作空间使用源代码进行编译，即把rosbridge作为其中一个功能包，按照如下命令顺序执行

sudo apt-get install ros-ROS1_DISTRO-rosauth # 将 ROS1_DISTRO 替换为ROS对应的版本名称

cd ~/ros_workspace/ # 替换 ros_workspace 为工作空间目录名称
source devel/setup.bash
cd src/
git clone -b ros1 https://github.com/RobotWebTools/rosbridge_suite.git
cd ..
catkin_make
source devel/setup.bash

此外，ROSIntegration使用包含在PyMongo包中的BSON，可以单独安装

sudo pip3 install pymongo

2、配置ROSIntegration

使用git命令下载ROSIntegration，放置在虚幻引擎项目文件Plugins文件夹下

cd unreal_engine_project # 替换 unreal_engine_project 为项目目录文件夹路径
mkdir Plugins # 如果没有 Plugins 文件夹则手动创建
cd Plugins
git clone https://github.com/code-iai/ROSIntegration.git

此时，ROSIntegration在虚幻项目中的文件结构如下：

unreal_engine_project/Plugins/ROSIntegration/ROSIntegration.uplugin

在虚幻引擎源代码UnrealEngine下的Engine/Source/Developer/DesktopPlatform/Private/DesktopPlatformBase.cpp文件中执行此操作

查找此行：

Arguments += " -Progress -NoEngineChanges -NoHotReloadFromIDE";

替换为：

Arguments += " -Progress";

然后重新编译引擎：

cd UnrealEngine
./Setup.sh
./GenerateProjectFiles.sh
make

编译完成后，启动项目并接受重建

（如果不进行上述步骤可能会遇到虚幻引擎自建项目打不开或遇到engine modules are out of date and cannot be compiled while the engine is running的情况）

创建一个新的C++虚幻项目，或打开现有项目

在内容浏览器中查找（在内容浏览器的右下角启用“查看选项”>“显示插件内容”）

点击“添加/导入”按钮下方的三条线按钮，展开左侧区域

选中“ROSIntegration“>“Classes”，右键ROSIntegrationGameInstance，点击下图黄色选项

打开新的C++类/蓝图对象，并更改ROSBridgeSeverHost 和ROSBridgeServerPort，如果是本地运行的ROSBridge，则改为127.0.0.1即可

打开“地图和模式”>“项目设置”，并将游戏实例设置为与新的游戏实例对象匹配，比如MyROSIntegrationGameInstance，而不是插件中的ROSIntegrationGameInstance!

使用Ctrl + Shift + S保存所有更改

3、使用ROSIntegration

要进行与 ROS 的简单发布/订阅通信，需要在创建一个新的C++ Actor，而非中文的角色（Charactor）。接着创建 SamplePubliser

SamplePublisher.h

#include "ROSIntegration/Classes/RI/Topic.h"
#include "ROSIntegration/Classes/ROSIntegrationGameInstance.h"
#include "ROSIntegration/Public/std_msgs/String.h"

注意：上述代码必须在#include "SamplePublisher.generated.h"之前，否则会报错

SamplePublisher.cpp

// Initialize a topic
UTopic *ExampleTopic = NewObject<UTopic>(UTopic::StaticClass());
UROSIntegrationGameInstance* rosinst = Cast<UROSIntegrationGameInstance>(GetGameInstance());
ExampleTopic->Init(rosinst->ROSIntegrationCore, TEXT("/example_topic"), TEXT("std_msgs/String"));

// (Optional) Advertise the topic
ExampleTopic->Advertise();

// Publish a string to the topic
TSharedPtr<ROSMessages::std_msgs::String> StringMessage(new ROSMessages::std_msgs::String("This is an example"));
ExampleTopic->Publish(StringMessage);

注意：上述代码放置在BeginPlay()函数中

进入unreal_engine_project/Source/unreal_engine_project目录（替换 unreal_engine_project 为真实的项目名称），打开unreal_engine_project.Build.cs文件

找到:

		PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore" });

添加ROSIntegrationy依赖，形如：

		PublicDependencyModuleNames.AddRange(new string[] { "Core", "CoreUObject", "Engine", "InputCore", "ROSIntegration" });

进入ROS工作空间的src目录，创建测试功能包：

catkin_create_pkg ue_test std_msgs rospy roscpp

编译并source：

catkin_make
source devel/setup.bash

创建一个监听者cpp文件：

cd ue_test/src
touch listener.cpp

打开cpp并键入如下代码：

#include "ros/ros.h"
#include "std_msgs/String.h"

/** * This tutorial demonstrates simple receipt of messages over the ROS system. */
void chatterCallback(const std_msgs::String::ConstPtr& msg) {
  ROS_INFO("I heard: [%s]", msg->data.c_str());
}

int main(int argc, char **argv) {
  /** * The ros::init() function needs to see argc and argv so that it can perform * any ROS arguments and name remapping that were provided at the command line. * For programmatic remappings you can use a different version of init() which takes * remappings directly, but for most command-line programs, passing argc and argv is * the easiest way to do it. The third argument to init() is the name of the node. * * You must call one of the versions of ros::init() before using any other * part of the ROS system. */
  ros::init(argc, argv, "listener");

  /** * NodeHandle is the main access point to communications with the ROS system. * The first NodeHandle constructed will fully initialize this node, and the last * NodeHandle destructed will close down the node. */
  ros::NodeHandle n;

  /** * The subscribe() call is how you tell ROS that you want to receive messages * on a given topic. This invokes a call to the ROS * master node, which keeps a registry of who is publishing and who * is subscribing. Messages are passed to a callback function, here * called chatterCallback. subscribe() returns a Subscriber object that you * must hold on to until you want to unsubscribe. When all copies of the Subscriber * object go out of scope, this callback will automatically be unsubscribed from * this topic. * * The second parameter to the subscribe() function is the size of the message * queue. If messages are arriving faster than they are being processed, this * is the number of messages that will be buffered up before beginning to throw * away the oldest ones. */
  ros::Subscriber sub = n.subscribe("/example_topic", 1000, chatterCallback);

  /** * ros::spin() will enter a loop, pumping callbacks. With this version, all * callbacks will be called from within this thread (the main one). ros::spin() * will exit when Ctrl-C is pressed, or the node is shutdown by the master. */
  ros::spin();

  return 0;
}

在CMakeLists.txt添加：

add_executable(listener src/listener.cpp)
target_link_libraries(listener ${catkin_LIBRARIES})
add_dependencies(listener listener)

4、测试ROSIntegration

启动rosbridge

roslaunch rosbridge_server rosbridge_tcp.launch bson_only_mode:=True

运行新建功能包的监听者

# rosrun <your package> talker 
# 比如
rosrun ue_test talker

将在UE中新建的SamplePublisher托入三维世界中，并点击运行

此时可以看到：

[INFO] [1588662504.536355639]: I heard: [This is an example]

恭喜你成功配置并运行了ROSIntegration！！！

三、ROSIntegrationVision下载与配置运行

1、虚幻引擎配置修改

在PATH_TO_UNREAL/Engine/Source/Programs/UnrealBuildTool/Platform/Linux/LinuxToolChain.cs中找到GetCLArguments_Global函数，并在其中添加语句Result += " -mf16c";，形如：

		protected virtual string GetCLArguments_Global(CppCompileEnvironment CompileEnvironment) {
			string Result = "";

			// build up the commandline common to C and C++
			Result += " -c";
			Result += " -pipe";
            Result += " -mf16c";

			if (ShouldUseLibcxx(CompileEnvironment.Architecture))
			{
				Result += " -nostdinc++";
				Result += " -I" + "ThirdParty/Linux/LibCxx/include/";
				Result += " -I" + "ThirdParty/Linux/LibCxx/include/c++/v1";
			}

而后重新编译虚幻引擎（注意如下语句必须都执行才算是重新编译）：

cd UnrealEngine
./Setup.sh
./GenerateProjectFiles.sh
make

2、配置ROSIntegrationVision

使用git命令下载ROSIntegrationVision，放置在虚幻引擎项目文件Plugins文件夹下

cd unreal_engine_project # 替换 unreal_engine_project 为项目目录文件夹路径
mkdir Plugins # 如果没有 Plugins 文件夹则手动创建
cd Plugins
git clone https://github.com/code-iai/ROSIntegrationVision/.git

如果你是在Linux上编译虚幻引擎4而非Windows，则在打开项目时可能会遇到

Building forest2Editor...
Performing 3 actions (6 in parallel)
[1/3] Compile Module.ROSIntegrationVision.cpp
In file included from .../Plugins/ROSIntegrationVision/Intermediate/Build/Linux/B4D820EA/UE4Editor/Development/ROSIntegrationVision/Module.ROSIntegrationVision.cpp:6:
.../Plugins/ROSIntegrationVision/Source/ROSIntegrationVision/Private/VisionComponent.cpp:754:4: error: use of undeclared identifier '_mm_div_epi16'; did you mean '_mm_min_epi16'?
_mm_div_epi16(
^~~~~~~~~~~~~
_mm_min_epi16
/home/pisces/Gitware/UnrealEngine/Engine/Extras/ThirdPartyNotUE/SDKs/HostLinux/Linux_x64/v17_clang-10.0.1-centos7/x86_64-unknown-linux-gnu/lib/clang/10.0.1/include/emmintrin.h:2412:1: note: '_mm_min_epi16' declared here
_mm_min_epi16(__m128i __a, __m128i __b)
^
1 error generated.
LogInit: Warning: Still incompatible or missing module: ROSIntegrationVision

这是由于官方参考了Windows for UVisionComponent上的编译问题：：convertDepth #28这一问题的回答，将源码改为了适配Windows的环境，但在Ubuntu18.04中并不存在_mm_div_epi16这一函数

因而，改变代码

void UVisionComponent::convertDepth(const uint16_t *in, __m128 *out) const {
  const size_t size = (Width * Height) / 4;
  for (size_t i = 0; i < size; ++i, in += 4, ++out)
  {
    // Divide by 100 here in order to convert UU (cm) into ROS units (m)
    *out = _mm_cvtph_ps(
      _mm_div_epi16(
        _mm_set_epi16(0, 0, 0, 0, *(in + 3), *(in + 2), *(in + 1), *(in + 0)),
        _mm_set_epi16(100, 100, 100, 100, 100, 100, 100, 100)
      )
    );// / 100;
  }
}

为

void UVisionComponent::convertDepth(const uint16_t *in, __m128 *out) const {
  const size_t size = (Width * Height) / 4;
  for (size_t i = 0; i < size; ++i, in += 4, ++out)
  {
    // Divide by 100 here in order to convert UU (cm) into ROS units (m)
    *out = _mm_cvtph_ps(_mm_set_epi16(
      0, 0, 0, 0, *(in + 3), *(in + 2), *(in + 1), *(in + 0))) / 100;
  }
}

即可成功自动编译打开项目

3、使用ROSIntegrationVision

在内容浏览器ROSIntegrationVision/ROSIntegrationVision/Private中包含VisionActor C++文件，将其托入三维世界中即可现实摄像头图像信息

4、问题

注意：使用时需要先在VisionActor.cpp中作如下修改

AVisionActor::AVisionActor() : AActor()
{
	UE_LOG(LogTemp, Warning, TEXT("VisionActor CTOR"));

	// Set this actor to call Tick() every frame. You can turn this off to improve performance if you don't need it.
	PrimaryActorTick.bCanEverTick = true;
    
    RootComponent = CreateDefaultSubobject<USceneComponent>(TEXT("Root"));
    SetRootComponent(RootComponent);
    
    vision = CreateDefaultSubobject<UVisionComponent>(TEXT("Vision"));
    vision->DisableTFPublishing = true;   // 添加
    //vision->ParentLink = "/world"; 注释掉
    vision->ParentLink = "desired_link";  // 添加
    vision->SetupAttachment(RootComponent);
}

将ROSIntegrationVision插件中的Binaries和Intermediate文件夹删除，重新打开项目，使引擎重新编译插件

如果在运行rosbridge时遇到如下问题

可以修改ROSIntegration/Source/ROSIntegration/Private/Conversion/Messages/sensor_msgs/SensorMsgsCameraInfoConverter.h文件

替换

	static void _bson_append_camera_info(bson_t *b, const ROSMessages::sensor_msgs::CameraInfo *msg)
	{
		// assert(CastMsg->D.Num() == 5); // TODO: use Unreal assertions
		assert(CastMsg->K.Num() == 9); // TODO: use Unreal assertions
		assert(CastMsg->R.Num() == 9);
		assert(CastMsg->P.Num() == 12);
		
		UStdMsgsHeaderConverter::_bson_append_child_header(b, "header", &msg->header);
		BSON_APPEND_INT32(b, "height", msg->height);
		BSON_APPEND_INT32(b, "width", msg->width);
		BSON_APPEND_UTF8(b, "distortion_model", TCHAR_TO_UTF8(*msg->distortion_model));
		_bson_append_double_tarray(b, "d", msg->D);
		_bson_append_double_tarray(b, "k", msg->K);
		_bson_append_double_tarray(b, "r", msg->R);
		_bson_append_double_tarray(b, "p", msg->P);	
		BSON_APPEND_INT32(b, "binning_x", msg->binning_x);
		BSON_APPEND_INT32(b, "binning_y", msg->binning_y);
		USensorMsgsRegionOfInterestConverter::_bson_append_child_roi(b, "roi", &msg->roi);
	}

为

	static void _bson_append_camera_info(bson_t *b, const ROSMessages::sensor_msgs::CameraInfo *msg)
	{
		// assert(CastMsg->D.Num() == 5); // TODO: use Unreal assertions
		assert(CastMsg->K.Num() == 9); // TODO: use Unreal assertions
		assert(CastMsg->R.Num() == 9);
		assert(CastMsg->P.Num() == 12);
		
		UStdMsgsHeaderConverter::_bson_append_child_header(b, "header", &msg->header);
		BSON_APPEND_INT32(b, "height", msg->height);
		BSON_APPEND_INT32(b, "width", msg->width);
		BSON_APPEND_UTF8(b, "distortion_model", TCHAR_TO_UTF8(*msg->distortion_model));
		_bson_append_double_tarray(b, "D", msg->D); // 替换
		_bson_append_double_tarray(b, "K", msg->K); // 替换
		_bson_append_double_tarray(b, "R", msg->R); // 替换
		_bson_append_double_tarray(b, "P", msg->P);	// 替换
		BSON_APPEND_INT32(b, "binning_x", msg->binning_x);
		BSON_APPEND_INT32(b, "binning_y", msg->binning_y);
		USensorMsgsRegionOfInterestConverter::_bson_append_child_roi(b, "roi", &msg->roi);
	}

如果相机图象FPS较低，可以考虑修改VisionComponent.cpp中 Framerate(1) 为 Framerate(100)

UVisionComponent::UVisionComponent() :
Width(640),
Height(480),
Framerate(100),    // change 1 to 100
UseEngineFramerate(false),
ServerPort(10000),
FrameTime(1.0f / Framerate),
TimePassed(0),
ColorsUsed(0)