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D435i use apriltag with OpenCV

apriltag​

官方网站

项目地址

编译安装​

git clone https://github.com/AprilRobotics/apriltag.git
cd apriltag
mkdir build
cd build/
cmake -DCMAKE_INSTALL_PREFIX=/usr/local -DCMAKE_BUILD_TYPE=Release ..
NUM_CPU=$(nproc)
make -j$(($NUM_CPU - 1))
sudo make install

librealsense2-AprilTag-OpenCV​

参考链接

配置 apriltag

// aprilTag config
apriltag_detector_t *td = apriltag_detector_create();
apriltag_family_t   *tf = tag36h11_create();
apriltag_detector_add_family(td, tf);
td->nthreads = 4;
  • apriltag_family_t 为标签的不同分类合集，这里选择 tag36h11，具体可以参考 User Guide 中的 choosing-a-tag-family

创建 img_header

cv::Mat gray_img;
cv::cvtColor(color_img, gray_img, cv::COLOR_BGR2GRAY);
// Make an image_u8_t header for the Mat data
image_u8_t img_header = { .width = gray_img.cols,
    .height = gray_img.rows,
    .stride = gray_img.cols,
    .buf = gray_img.data
};

执行检测

zarray_t *detections = apriltag_detector_detect(td, &img_header);

绘制结果

for(int i = 0; i < zarray_size(detections); ++i){
    apriltag_detection_t *det;
    zarray_get(detections, i, &det);
    for(size_t i = 0; i < 4; ++i){
        cv::line(color_img, cv::Point(static_cast<int>(det->p[i][0]), static_cast<int>(det->p[i][1])),
                cv::Point(static_cast<int>(det->p[(i+1)%4][0]), static_cast<int>(det->p[(i+1)%4][1])),
                cv::Scalar(0xff, 0xff, 0), 2);
    }

    stringstream ss;
    ss << det->id;
    cv::String text = ss.str();
    int fontface = cv::FONT_HERSHEY_SCRIPT_SIMPLEX;
    double fontscale = 1.0;
    int baseline;
    cv::Size textsize = cv::getTextSize(text, fontface, fontscale, 2,
                                    &baseline);
    putText(color_img, text, cv::Point( static_cast<int>(det->c[0]-textsize.width/2),
                                        static_cast<int>(det->c[1]+textsize.height/2)),
                                        fontface, fontscale, cv::Scalar(0xff, 0x99, 0), 2);
}

imshow("color_img", color_img);

最终效果

参考​