ros中find_package指令是什么意思

在ROS中，`find_package`指令用于查找和引入其他ROS软件包。它会检查系统中是否安装了特定软件包，如果找到该软件包，它会导入其构建和运行所需的信息和文件。

使用`find_package`指令需要指定软件包的名称和版本号，例如：

find_package(catkin REQUIRED COMPONENTS roscpp)

此指令告诉ROS系统查找名为`roscpp`的软件包，并将其作为catkin构建系统的依赖项。如果ROS系统找不到该软件包，它将抛出一个错误。

`find_package`指令还可以用来查找和导入其他依赖项，如Boost库、Qt库等。

相关问题

# toplevel CMakeLists.txt for a catkin workspace # catkin/cmake/toplevel.cmake cmake_minimum_required(VERSION 3.0.2) project(Project) set(CATKIN_TOPLEVEL TRUE) # search for catkin within the workspace set(_cmd "catkin_find_pkg" "catkin" "${CMAKE_SOURCE_DIR}") execute_process(COMMAND ${_cmd} RESULT_VARIABLE _res OUTPUT_VARIABLE _out ERROR_VARIABLE _err OUTPUT_STRIP_TRAILING_WHITESPACE ERROR_STRIP_TRAILING_WHITESPACE ) if(NOT _res EQUAL 0 AND NOT _res EQUAL 2) # searching fot catkin resulted in an error string(REPLACE ";" " " _cmd_str "${_cmd}") message(FATAL_ERROR "Search for 'catkin' in workspace failed (${_cmd_str}): ${_err}") endif() # include catkin from workspace or via find_package() if(_res EQUAL 0) set(catkin_EXTRAS_DIR "${CMAKE_SOURCE_DIR}/${_out}/cmake") # include all.cmake without add_subdirectory to let it operate in same scope include(${catkin_EXTRAS_DIR}/all.cmake NO_POLICY_SCOPE) add_subdirectory("${_out}") else() # use either CMAKE_PREFIX_PATH explicitly passed to CMake as a command line argument # or CMAKE_PREFIX_PATH from the environment if(NOT DEFINED CMAKE_PREFIX_PATH) if(NOT "$ENV{CMAKE_PREFIX_PATH}" STREQUAL "") if(NOT WIN32) string(REPLACE ":" ";" CMAKE_PREFIX_PATH $ENV{CMAKE_PREFIX_PATH}) else() set(CMAKE_PREFIX_PATH $ENV{CMAKE_PREFIX_PATH}) endif() endif() endif() # list of catkin workspaces set(catkin_search_path "") foreach(path ${CMAKE_PREFIX_PATH}) if(EXISTS "${path}/.catkin") list(FIND catkin_search_path ${path} _index) if(_index EQUAL -1) list(APPEND catkin_search_path ${path}) endif() endif() endforeach() # search for catkin in all workspaces set(CATKIN_TOPLEVEL_FIND_PACKAGE TRUE) find_package(catkin QUIET NO_POLICY_SCOPE PATHS ${catkin_search_path} NO_DEFAULT_PATH NO_CMAKE_FIND_ROOT_PATH) unset(CATKIN_TOPLEVEL_FIND_PACKAGE) if(NOT catkin_FOUND) message(FATAL_ERROR "find_package(catkin) failed. catkin was neither found in the workspace nor in the CMAKE_PREFIX_PATH. One reason may be that no ROS setup.sh was sourced before.") endif() endif() catkin_workspace()在哪添加target_link_libraries(your_target_name avcodec avformat swscale)

在您的 CMakeLists.txt 文件中，将 `target_link_libraries()` 指令添加到 `add_subdirectory("${_out}")` 的下方。具体位置如下所示：

...

# include catkin from workspace or via find_package()
if(_res EQUAL 0)
  set(catkin_EXTRAS_DIR "${CMAKE_SOURCE_DIR}/${_out}/cmake")
  # include all.cmake without add_subdirectory to let it operate in same scope
  include(${catkin_EXTRAS_DIR}/all.cmake NO_POLICY_SCOPE)
  add_subdirectory("${_out}")

  # Add the target_link_libraries() here
  target_link_libraries(your_target_name avcodec avformat swscale)

else
  # use either CMAKE_PREFIX_PATH explicitly passed to CMake as a command line argument
  # or CMAKE_PREFIX_PATH from the environment
  if(NOT DEFINED CMAKE_PREFIX_PATH)
    if(NOT "$ENV{CMAKE_PREFIX_PATH}" STREQUAL "")
      if(NOT WIN32)
        string(REPLACE ":" ";" CMAKE_PREFIX_PATH $ENV{CMAKE_PREFIX_PATH})
      else()
        set(CMAKE_PREFIX_PATH $ENV{CMAKE_PREFIX_PATH})
      endif()
    endif()
  endif()

  ...
endif()

...

请注意将 `your_target_name` 替换为您实际的目标名称。这将在生成目标时链接 avcodec、avformat 和 swscale 库。

如果您还有其他问题，请随时提问。

在noetic环境中写出调取rtamap-ros的launch文件

首先，确保已经安装了rtabmap_ros软件包。然后，按照以下步骤编写调用rtabmap_ros的launch文件：

1. 创建一个名为“rtabmap.launch”的新文件，使用以下命令将其保存在ROS包的“launch”文件夹中：

roscd <your_package_name>/launch
touch rtabmap.launch

2. 在rtabmap.launch文件中添加以下内容：

<launch>
  <node pkg="rtabmap_ros" type="rtabmap" name="rtabmap" output="screen">
    <remap from="~subscribe_depth/image_rect" to="/camera/depth_registered/image_rect_raw"/>
    <remap from="~subscribe_stereo/left/image_rect" to="/camera/left/image_rect_color"/>
    <remap from="~subscribe_stereo/right/image_rect" to="/camera/right/image_rect_color"/>
    <param name="database_path" type="string" value="$(find <your_package_name>)/data/rtabmap.db"/>
  </node>
</launch>

3. 解释一下上述代码。在这个launch文件中，我们启动了rtabmap_ros节点，并将其命名为“rtabmap”。我们通过remap指令将相机采集到的图像话题重映射到rtabmap_ros所需要的话题。最后，我们设置了rtabmap_ros节点的数据库路径。

4. 运行以下命令启动rtabmap_ros节点：

roslaunch <your_package_name> rtabmap.launch

5. 如果一切正常，你将会在终端窗口中看到rtabmap_ros节点正在运行，并且可以在相应的话题中观察到rtabmap_ros处理的数据。