我使用ros-indigo和ubuntu 14.04。我用usb_cam从相机获取帧，但现在我不能完成相同的任务。如何在ROS上使用usb_cam节点？
如果我运行rosbuild_ws/package_dir$ roslaunch camera.launch命令，我得到以下的输出：
Unable to open camera calibration file [/home/user/.ros/camera_info/head_camera.yaml] [ WARN] [1436602681.552893640]: Camera calibration file /home/user/.ros/camera_info/head_camera.yaml not found. [ INFO] [1436602681.552918876]: Starting 'head_camera' (/dev/video0) at 640x480 via mmap (yuyv) at 30 FPS [ WARN] [1436602681.584193482]: unknown control 'white_balance_temperature_auto' [ WARN] [1436602681.587047162]: unknown control 'focus_auto'处理这些错误&警告，我尝试安装usb_Cam。我跑rosdep install usb_cam，终端说#All required rosdeps installed successfully。我使用roscd usb_cam转到usb_cam文件夹。
然后我运行下面的命令：
/opt/ros/indigo/share/usb_cam$ rosmake usb_cam No Makefile in package usb_cam [ rosmake ] Results: [ rosmake ] Built 39 packages with 0 failures. [ rosmake ] Summary output to directory最后，我跑rosbuild_ws/package_dir$ roslaunch camera.launch，但我得到同样的消息。我无法看到从usb相机拍摄的画面。如何使用usb_cam从usb cam获取帧？ camera.launch的
内容：
<launch> <node name="usb_cam" pkg="usb_cam" type="usb_cam_node" output="screen" > <param name="video_device" value="/dev/video0" /> <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>来源
2015-07-11 zumma
A 回答 0
我不知道的警告，但我敢肯定，你已经可以访问摄像机。 关于帧速率，你可以找到它usb_cam /节点/ usb_cam_node.cpp 内的默认帧速率应为30 你可以找到你需要的所有参数：
node_.param("video_device", video_device_name_, std::string("/dev/video0")); node_.param("brightness", brightness_, -1); //0-255, -1 "leave alone" node_.param("contrast", contrast_, -1); //0-255, -1 "leave alone" node_.param("saturation", saturation_, -1); //0-255, -1 "leave alone" node_.param("sharpness", sharpness_, -1); //0-255, -1 "leave alone" // possible values: mmap, read, userptr node_.param("io_method", io_method_name_, std::string("mmap")); node_.param("image_width", image_width_, 640); node_.param("image_height", image_height_, 480); node_.param("framerate", framerate_, 30); // possible values: yuyv, uyvy, mjpeg, yuvmono10, rgb24 node_.param("pixel_format", pixel_format_name_, std::string("mjpeg")); // enable/disable autofocus node_.param("autofocus", autofocus_, false); node_.param("focus", focus_, -1); //0-255, -1 "leave alone" // enable/disable autoexposure node_.param("autoexposure", autoexposure_, true); node_.param("exposure", exposure_, 100); node_.param("gain", gain_, -1); //0-100?, -1 "leave alone" // enable/disable auto white balance temperature node_.param("auto_white_balance", auto_white_balance_, true); node_.param("white_balance", white_balance_, 4000); // load the camera info node_.param("camera_frame_id", img_.header.frame_id, std::string("head_camera")); node_.param("camera_name", camera_name_, std::string("head_camera")); node_.param("camera_info_url", camera_info_url_, std::string(""));，那么你可能会改变他们在发射文件是这样的：
<param name="autoexposure" value="false" /> <param name="auto_whitebalance" value="false" /> <param name="auto_focus" value="false" /> <param name="auto_brigthness" value="false" />