ROS2 摄像头校准

1. ROS1 用的是 USB_CAM, ROS2用的是 v4l2_camera

sudo apt install ros-rolling-v4l2-camera ros-rolling-vision-opencv ros-rolling-image-transport-plugins ros-rolling-image-transport ros-rolling-image-common
sudo apt install python3-polled-camera polled-camera-tool libpolled-camera0d
sudo apt install libtheora-dev libogg-dev libboost-python-dev
sudo apt-get install -y libssl-dev libusb-1.0-0-dev pkg-config libgtk-3-dev
sudo apt-get install -y libglfw3-dev libgl1-mesa-dev libglu1-mesa-dev
也可考虑源码安装， 这样可以保证更新
git clone https://github.com/ros-perception/image_pipeline.git
cd image_pipeline;
git checkout ros2
colcon build --symlink-install
source 安装目录/setup.bash
## Wiki 参考  https://index.ros.org/r/v4l2_camera/#foxy

ros2 run v4l2_camera v4l2_camera_node --ros-args -p video_device:="/dev/video2" -p image_size=[1280,720]

出现
[INFO] [1597918407.198064148] [v4l2_camera]: Starting camera
[INFO] [1597918407.839159913] [v4l2_camera]: using default calibration URL
[INFO] [1597918407.839354370] [v4l2_camera]: camera calibration URL: file:///home/iibull/.ros/camera_info/sunplusit_inc:_pc_camera.yaml
[ERROR] [1597918407.839576699] [camera_calibration_parsers]: Unable to open camera calibration file [/home/iibull/.ros/camera_info/sunplusit_inc:_pc_camera.yaml]
[WARN] [1597918407.839643757] [v4l2_camera]: Camera calibration file /home/iibull/.ros/camera_info/sunplusit_inc:_pc_camera.yaml not found

发布话题
iibull@BIG:/$ ros2 topic list
/camera_info
/image_raw
/image_raw/compressed
/image_raw/compressedDepth
/image_raw/theora
/parameter_events
/rosout

/image_raw/compressed 是不能被  Rviz2 or showimage 看的， 所以 image_transport 的 republish 节点可以做此转换。 

ros2 run rqt_image_view rqt_image_view  使用 /image_raw 以及 /image_raw/compressed 话题可以看到图像.

ros2 run image_transport republish compressed --ros-args --remap in/compressed:=image_raw/compressed --ros-args --remap out:=image_raw/uncompressed
compressed - the transport to use for input, in this case 'compressed'. Alternative: raw, to republish the raw /image_raw topic
				
				
					in/compressed:=image_raw/compressed - by default, republish uses the topics in and out, or in/compressed for example if the input transport is 'compressed'. This parameter is a ROS remapping rule to map those names to the actual topic to use.
				
				
					raw - the transport to use for output. If omitted, all available transports are provided.
				
				
					out:=image_raw/uncompressed - remapping of the output topic.
compressed - the transport to use for input, in this case 'compressed'. Alternative: raw, to republish the raw /image_raw topic
in/compressed:=image_raw/compressed - by default, republish uses the topics in and out, or in/compressed for example if the input transport is 'compressed'. This parameter is a ROS remapping rule to map those names to the actual topic to use.
raw - the transport to use for output. If omitted, all available transports are provided.
out:=image_raw/uncompressed - remapping of the output topic.
打开 rviz2. fixed frame 改成 camera, 然后添加 /image_raw/uncompressed 的topic 显示。 则可以看到图像了。

//现在进行校准。
参考  

执行 ros2 run camera_calibration cameracalibrator
出现错误
RuntimeError: FATAL: module compiled as little endian, but detected different endianness at runtime
...
...
SystemError: initialization of cv_bridge_boost raised unreported exception
cv_bridge是OpenCV与ROS之间的格式转换桥梁。 higer 版本编译器中应当移除 boost endian APIs， 目前官网github上有改好的，ubuntu仓库还没有更新，需要手动编译。 （害得我查了很久）

    解决方法： 参考 

下载地址：https://github.com/ros-perception/vision_opencv

（这个仓库中包含多个包，下载之后只需要把cv_bridge拷贝到指定目录即可）

OK, 那么在自己的工作空间内。 git clone https://github.com/ros-perception/vision_opencv.git
cd vision_opencv/
git checkout ros2
colcon build --symlink-install

sudo apt install python3-numpy
pip3 install opencv-python
source 自己的安装目录/install/setup.bash
再次执行 cameracalibration 就没有问题了。

ros2 run camera_calibration cameracalibrator --size 7x9 --square 0.02 image:=/image_raw camera:=/custom_camera 命令成功后就会出现一个摄像头窗口

摄像头参数
Camera Name:
-c, --camera_name
        name of the camera to appear in the calibration file  ##校准文件中，摄像头的名字

棋盘参数
Chessboard Options:
You must specify one or more chessboards as pairs of --size and--square options.

  -p PATTERN, --pattern=PATTERN
                    calibration pattern to detect - 'chessboard','circles', 'acircles','charuco'
  -s SIZE, --size=SIZE
                    chessboard size as NxM, counting interior corners (e.g. a standard chessboard is 7x7)
  -q SQUARE, --square=SQUARE
                    chessboard square size in meters

ROS 选项
ROS Communication Options:
 --approximate=APPROXIMATE
                    allow specified slop (in seconds) when pairing images from unsynchronized stereo cameras
 --no-service-check
                    disable check for set_camera_info services at startup

Calibration Optimizer Options:

 --fix-principal-point
                    fix the principal point at the image center
 --fix-aspect-ratio
                    enforce focal lengths (fx, fy) are equal
 --zero-tangent-dist
                    set tangential distortion coefficients (p1, p2) to
                    zero
 -k NUM_COEFFS, --k-coefficients=NUM_COEFFS
                    number of radial distortion coefficients to use (up to
                    6, default 2)
 --disable_calib_cb_fast_check
                    uses the CALIB_CB_FAST_CHECK flag for findChessboardCorners

去  生成自己的 校准图片打印， 7x9要做8行10列的图calib.pdf。直接放在屏幕上， 100%显示也是可以
前后左右上下移动， 同时各个方向上倾斜， 最终得到calibrate按钮可用并点击（1分钟计算时间）， 然后点击保存， 获得  “/tmp/calibrationdata.tar.gz”
tar -xvf calibration.tar.gz

iibull@BIG:/tmp$ tar -xvf calibrationdata.tar.gz
left-0000.png
left-0001.png
left-0002.png
left-0003.png
left-0004.png
left-0005.png
left-0006.png
left-0007.png
left-0008.png
left-0009.png
left-0010.png
left-0011.png
left-0012.png
left-0013.png
left-0014.png
left-0015.png
left-0016.png
left-0017.png
left-0018.png
left-0019.png
left-0020.png
left-0021.png
left-0022.png
left-0023.png
left-0024.png
left-0025.png
left-0026.png
left-0027.png
left-0028.png
left-0029.png
left-0030.png
left-0031.png
left-0032.png
left-0033.png
left-0034.png
left-0035.png
left-0036.png
left-0037.png
left-0038.png
left-0039.png
left-0040.png
left-0041.png
ost.yaml
ost.txt

ost.yaml 就是我们最终想要的校准文件。

修改 ost.yaml 文件中 的内存  camera_name: sunplusit_inc:_pc_camera
cp ost.yaml /home/iibull/.ros/camera_info/sunplusit_inc:_pc_camera.yaml

然后重启 v4l2
ros2 run v4l2_camera v4l2_camera_node --ros-args -p video_device:="/dev/video2" -r image_raw:=/my_camera/image_raw -r camera_info:=/my_camera/camera_info -p camera_info_url:=file:///home/iibull/.ros/camera_info/mycamera.yaml
这里mycamera.yaml是我自己的配置文件。

通过 ros2 topic echo /my_camera/camera_info 看到输出的内容和 mycamera.yaml 内容是一样的。

目前官方的代码有些问题， 不支持 camera_info_url的导入。 只能自己修改一下。
git clone https://gitlab.com/boldhearts/ros2_v4l2_camera.git


vi src/ros2_v4l2_camera/src/v4l2_camera.cpp
添加
void V4L2Camera::createParameters()
{
  // Node parameters
  output_encoding_ = declare_parameter("output_encoding", std::string{"rgb8"});
  declare_parameter("camera_info_url");
  ...
  ...
  ...


colcon build --symlink-install
source install/setup.bash

//删除旧的
sudo apt remove ros-rolling-v4l2-camera