Use usb_cam to open multiple cameras at the same time

最近由于项目需要,Multiple cameras need to be turned on at the same time,虽然可以用opencvTo write the corresponding camera to open the program ; 但是,还是想用ros中提供的usb_camto open multiple cameras.

通过usb_camGo open a camera,不用下载源码,可以直接安装usb_cam去调用launchFile open camera.

• 安装方式：（ubuntu16.04）

 sudo apt-get install ros-kinetic-usb-cam

• 打开摄像头（The default open index is 0的摄像头）

roslaunch usb_cam usb_cam-test.launch

• How to view camera index

ls /dev/video*

• Open cameras of other indexes need to be modified usb_cam-test.launch文件中“video_device”这一项;Modify the index to the camera index you want to open.

  <node name="usb_cam" pkg="usb_cam" type="usb_cam_node" output="screen" >
    <param name="video_device" value="/dev/video0" />   #修改此处
    <param name="image_width" value="640" />
    <param name="image_height" value="480" />
    <param name="pixel_format" value="yuyv" />
    <param name="camera_frame_id" value="usb_cam" />
    <param name="io_method" value="mmap"/>
  </node>
 

  <!--<node name="image_view" pkg="image_view" type="image_view" respawn="false" output="screen">
    <remap from="image" to="/usb_cam/image_raw"/>
    <param name="autosize" value="true" />
  </node>-->
</launch>

Install the source code to open the camera：

• 下载源码

git clone https://github.com/bosch-ros-pkg/usb_cam.git

• 创建工作空间
  详情参照https://blog.csdn.net/xp_fangfei/article/details/123412772?spm=1001.2014.3001.5502
• 把下载好的usb_caminto the newly created workspacesrc下,进行编译即可.
• usb_cam树结构

.
├── AUTHORS.md
├── CHANGELOG.rst
├── CMakeLists.txt
├── include
│   └── usb_cam
│       └── usb_cam.h
├── launch
│   ├── usb_cam-test.launch
├── LICENSE
├── mainpage.dox
├── nodes
│   └── usb_cam_node.cpp
├── package.xml
├── README.md
└── src
    ├── LICENSE
    └── usb_cam.cpp

• Opening multiple cameras at the same time only needs to increase accordinglyusb_cam_node.cpp节点即可;usb_cam_node.cppThe contents that need to be changed are as follows：

# 修改内容一 
usb_cam_node.cpp 中第89行 topic名称进行修改：
89 image_pub_ = it.advertiseCamera("image_raw", 1);
# 修改内容二
usb_cam_node.cpp 271line the node tomasterModify the node name registered in ,In order to avoid the registration of the same name,编译错误
271 ros::init(argc, argv, "usb_cam");

Example 1：
我新建了一个名为usb_cam_node1.cpp的节点,修改如下：

89 image_pub_ = it.advertiseCamera("image_raw_new", 1);
271 ros::init(argc, argv, "usb_cam1");

• 对应的CMakeLists.txt进行修改

add_executable  #Add the executable file name corresponding to the node name

Example 1：

#CMakeLists.txteach time a node is added,Correspondingly add the following two parts
add_executable(${PROJECT_NAME}_node1 nodes/usb_cam_node1.cpp)  
target_link_libraries(${PROJECT_NAME}_node1
  ${PROJECT_NAME}
  ${avcodec_LIBRARIES}
  ${swscale_LIBRARIES}
  ${catkin_LIBRARIES}
)

• 对应的launch文件进行修改

<node name="usb_cam" pkg="usb_cam" type="usb_cam_node" output="screen" >
name="usb_cam" # Change it to the appropriate topic name,Used to communicate with other node topic names
type="usb_cam_node"  #Modify it to the corresponding node name

Example 1：
usb_cam-test1.launch 内容如下

<launch>
  <node name="usb_cam_node1" pkg="usb_cam" type="usb_cam_node1" output="screen" >
    <param name="video_device" value="/dev/video1" />
    <param name="image_width" value="640" />
    <param name="image_height" value="480" />
    <param name="pixel_format" value="yuyv" />
    <param name="camera_frame_id" value="usb_cam" />
    <param name="io_method" value="mmap"/>
  </node>
  <!--<node name="image_view_node1" pkg="image_view" type="image_view" respawn="false" output="screen">
    <remap from="image" to="/usb_cam_node1/image_raw_new"/>
    <param name="autosize" value="true" />
  </node>-->
</launch>

• 每增加一个节点,对应一个launch文件;最后写一个launchfile to start several cameras at the same timelaunch文件,就可以实现usb_camTurn on the function of multiple cameras.

Example 1：

usb_cam-total.launch 内容如下：

<launch>

  <include file="$(find usb_cam)/launch/usb_cam-test.launch" />
  <include file="$(find usb_cam)/launch/usb_cam-test1.launch" />

</launch>