修改摄像头分辨率并发布Topic

来源：互联网发布：淘宝买家改差评编辑：程序博客网时间：2024/06/11 19:41

最近买了个1280x960的黑白摄像头，默认输出640x480，需要调节摄像头参数。

最终代码：

#include <iostream>#include <opencv2/core/core.hpp>#include <opencv2/highgui/highgui.hpp>#include <opencv2/features2d/features2d.hpp>#include <opencv2/imgproc/imgproc.hpp>#include <opencv2/calib3d/calib3d.hpp>#include <opencv2/nonfree/nonfree.hpp>#include <sensor_msgs/Image.h>#include <sensor_msgs/image_encodings.h>#include <cv_bridge/cv_bridge.h>#include <ros/ros.h>#include <image_transport/image_transport.h>using namespace std;using namespace cv;int main(int argc, char** argv){    sensor_msgs::ImagePtr img_msg; // >> message to be sent    cv::Mat frame;    ros::init(argc, argv, "cam");    ros::NodeHandle nh;    int32_t device_id(0);    int32_t image_width(1280);    int32_t image_height(960);    nh.getParam("device_id",device_id);    nh.getParam("image_width",image_width);    nh.getParam("image_height",image_height);    VideoCapture cap(device_id); // open the default camera    if(!cap.isOpened())cout<<"Error open cam!"<<endl;    if(!cap.isOpened())return -1;// check if we succeeded    cout<<"Camera is open,to topic:cam/image"<<endl;    bool bsw,bsh;    if(cap.get(CV_CAP_PROP_FRAME_WIDTH)!=image_width)    {        bsw = cap.set(CV_CAP_PROP_FRAME_WIDTH,image_width);        bsh = cap.set(CV_CAP_PROP_FRAME_HEIGHT,image_height);    }    cout<<"Resolution:"<<cap.get(CV_CAP_PROP_FRAME_WIDTH)<<"x"<<cap.get(CV_CAP_PROP_FRAME_HEIGHT)<<endl;    image_transport::ImageTransport it(nh);    image_transport::Publisher pub_img = it.advertise("cam/image", 1);    ros::Rate rate(50);    while(nh.ok())    {        cap >> frame; // get a new frame from camera        img_msg=cv_bridge::CvImage(std_msgs::Header(), "bgr8", frame).toImageMsg();        pub_img.publish(img_msg); // ros::Publisher pub_img = node.advertise<sensor_msgs::Image>("topic", queuesize);        ros::spinOnce();        rate.sleep();    }    return 0;}

这里有个问题，就是插上摄像头第一次可以调用set进行写入参数，但是第二次就会报错：
HIGHGUI ERROR: V4L: Initial Capture Error: Unable to load initial memory buffers.
现在还没搞清什么原因，我就才去了一个办法：

    if(cap.get(CV_CAP_PROP_FRAME_WIDTH)!=image_width)    {        bsw = cap.set(CV_CAP_PROP_FRAME_WIDTH,image_width);        bsh = cap.set(CV_CAP_PROP_FRAME_HEIGHT,image_height);    }

就是一般情况不需要频繁调节分辨率，所以先读取现在的分辨率，如果和想要的一致（插上摄像头第一次运行已经配置好了）就不执行set函数了。

然后是launch文件：

<launch>  <param name="device_id" value="0"/>  <param name="image_width" value="1280"/>  <param name="image_height" value="960"/>  <node pkg="demo" type="cam" name="cam" output="screen">  </node></launch>

还没完，标定时发现没发布camera_info信息。待续

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