无法在ROS Kinetic和Python3中使用cv_bridge

Question

无法在ROS Kinetic和Python3中使用cv_bridge

9

我是一位有用的助手，可以为您进行翻译。

我原先在Ubuntu 14.04上使用ROS Indigo和Python3开发计算机视觉项目，但后来需要转移到Ubuntu 16.04上使用ROS Kinetic。在此过程中，我遇到了多个问题：

1）我已经安装了OpenCV，但无法在Python3中导入它，出现以下错误信息：

Traceback (most recent call last):
  File "test.py", line 2, in <module>
    import cv2
ImportError: /opt/ros/kinetic/lib/python2.7/dist-packages/cv2.so: 
undefined symbol: PyCObject_Type

我发现只需要重命名cv2.so文件。

cd /opt/ros/kinetic/lib/python2.7/dist-packages/
sudo mv cv2.so cv2_ros.so

1) 我成功导入了cv2并使用它。

2) 然后我无法导入rospy，但安装python3-catkin-pkg-modules和python3-rospkg-modules解决了这个问题。

3) 最后我遇到了一个cv_bridge问题，它显示：

[ERROR] [1520780674.845066]: bad callback: <bound method ViewsBuffer.update of <__main__.ViewsBuffer object at 0x7f5f45a07f28>>
Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rospy/topics.py", line 750, in _invoke_callback
    cb(msg)
  File "test.py", line 48, in update
    im = self.bridge.imgmsg_to_cv2(im, "bgr8")
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/cv_bridge/core.py", line 163, in imgmsg_to_cv2
    dtype, n_channels = self.encoding_to_dtype_with_channels(img_msg.encoding)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/cv_bridge/core.py", line 99, in encoding_to_dtype_with_channels
    return self.cvtype2_to_dtype_with_channels(self.encoding_to_cvtype2(encoding))
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/cv_bridge/core.py", line 91, in encoding_to_cvtype2
    from cv_bridge.boost.cv_bridge_boost import getCvType
ImportError: dynamic module does not define module export function (PyInit_cv_bridge_boost)

我相信问题出在cv_bridge_boost.so文件中。我还尝试从https://github.com/ros-perception/vision_opencv构建cv_bridge，但它会自动为python2.7构建，我试图在CMakeLists.txt中稍微修改一下以指定python3，但我对CMakeLists不是很熟悉，所以没有成功。我还尝试将cv_bridge模块复制到我的项目文件夹中，但这没有什么改变，它仍然指向那个cv_bridge_boost.so文件。还要提到的一件事是，cv_bridge在python2.7上运行良好，但我的项目需要python3.5。

- Egor

3个回答

1

我在系统中安装了anaconda3，并且在使用cv_bridge时遇到了类似的问题。当我尝试使用catkin build cv_bridge进行构建时，它会报错。我使用来自conda的python3.7。我的catkin配置命令是：

catkin config -DPYTHON_EXECUTABLE=/home/akashbaskaran/anaconda3/bin/python3 -DPYTHON_INCLUDE_DIR=/home/akashbaskaran/anaconda3/include/python3.7m -DPYTHON_LIBRARY=/home/akashbaskaran/anaconda3/lib/libpython3.7m.so

解决方案：我做了几件事情，问题得到了解决。

由于使用了anaconda，可执行文件和include目录应该是当前虚拟环境内的文件。 -DPYTHON_EXECUTABLE=/home/akashbaskaran/anaconda3/envs/tf/bin/python3.6 -DPYTHON_INCLUDE_DIR=/home/akashbaskaran/anaconda3/envs/tf/include/python3.6m -DPYTHON_LIBRARY=/home/akashbaskaran/anaconda3/envs/tf/lib/libpython3.6m.so
当我尝试构建cv_bridge时，出现了构建问题。如果您遇到类似的问题，请删除除src以外的所有文件夹。然后从终端运行catkin_make（确保您在catkin_workspace内）。
源代码当前工作区source devel/setup.bash

现在，import cv2from cv_bridge.boost.cv_bridge_boost import getCvType应该可以正常工作，不会出现错误。

- Akash Baskaran

0

我的基本环境：Ubuntu 18.04和ROS Melodic。

我正在conda的虚拟环境（Python3.7）中编译cv_bridge，并且我遇到了与@Jibril相同的问题。当我运行catkin build cv_bridge时，我得到1个成功的软件包和3个被跳过/列入黑名单的软件包。

我使用的命令是

# 1
catkin init

# 2
catkin config \
-DPYTHON_EXECUTABLE=/home/zed/anaconda3/envs/yolov5/bin/python3.7 \
-DPYTHON_INCLUDE_DIR=/home/zed/anaconda3/envs/yolov5/include/python3.7m \
-DPYTHON_LIBRARY=/home/zed/anaconda3/envs/yolov5/lib/libpython3.7m.so

# 3
catkin config --install

# 4
catkin build cv_bridge

然后我在{ws}/log文件夹中查看日志文件，找到了关于--install-layout参数的错误信息。参考issue中的解决方案，我在原始命令中添加了-DSETUPTOOLS_DEB_LAYOUT=OFF，最终成功编译完成。

我修改后的命令是：

# 1
catkin init

# 2
catkin config \
-DPYTHON_EXECUTABLE=/home/zed/anaconda3/envs/yolov5/bin/python3.7 \
-DPYTHON_INCLUDE_DIR=/home/zed/anaconda3/envs/yolov5/include/python3.7m \
-DPYTHON_LIBRARY=/home/zed/anaconda3/envs/yolov5/lib/libpython3.7m.so \
-DSETUPTOOLS_DEB_LAYOUT=OFF

# 3
catkin config --install

# 4
catkin build cv_bridge

当你需要在另一个ROS工作区中使用已编译的cv_bridge时，你只需执行 source {PATH_cv_bridge_ws}/install/setup.bash --extend，然后执行 source {PATH_current_ws}/devel/setup.bash。

如果上述解决方案对你不起作用，你也可以尝试一些在这个issue中提出的cv_bridge替代方案！

- G.Chenhui

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- hexonxons · Accepted Answer

你是正确的，你应该使用Python3构建cv_bridge。
你可以通过传递

-DPYTHON_EXECUTABLE=/usr/bin/python3 -DPYTHON_INCLUDE_DIR=/usr/include/python3.5m -DPYTHON_LIBRARY=/usr/lib/x86_64-linux-gnu/libpython3.5m.so

cmake 的参数。或者，如果您正在使用 catkin 构建软件包，可以执行以下步骤：

# `python-catkin-tools` is needed for catkin tool
# `python3-dev` and `python3-catkin-pkg-modules` is needed to build cv_bridge
# `python3-numpy` and `python3-yaml` is cv_bridge dependencies
# `ros-kinetic-cv-bridge` is needed to install a lot of cv_bridge deps. Probaply you already have it installed.
sudo apt-get install python-catkin-tools python3-dev python3-catkin-pkg-modules python3-numpy python3-yaml ros-kinetic-cv-bridge
# Create catkin workspace
mkdir catkin_workspace
cd catkin_workspace
catkin init
# Instruct catkin to set cmake variables
catkin config -DPYTHON_EXECUTABLE=/usr/bin/python3 -DPYTHON_INCLUDE_DIR=/usr/include/python3.5m -DPYTHON_LIBRARY=/usr/lib/x86_64-linux-gnu/libpython3.5m.so
# Instruct catkin to install built packages into install place. It is $CATKIN_WORKSPACE/install folder
catkin config --install
# Clone cv_bridge src
git clone https://github.com/ros-perception/vision_opencv.git src/vision_opencv
# Find version of cv_bridge in your repository
apt-cache show ros-kinetic-cv-bridge | grep Version
    Version: 1.12.8-0xenial-20180416-143935-0800
# Checkout right version in git repo. In our case it is 1.12.8
cd src/vision_opencv/
git checkout 1.12.8
cd ../../
# Build
catkin build cv_bridge
# Extend environment with new package
source install/setup.bash --extend

并且

$ python3

Python 3.5.2 (default, Nov 23 2017, 16:37:01) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from cv_bridge.boost.cv_bridge_boost import getCvType
>>>

如果您遇到了下一个错误

CMake Error at /usr/share/cmake-3.5/Modules/FindBoost.cmake:1677 (message):
  Unable to find the requested Boost libraries.

  Boost version: 1.58.0

  Boost include path: /usr/include

  Could not find the following Boost libraries:

          boost_python3

  No Boost libraries were found.  You may need to set BOOST_LIBRARYDIR to the
  directory containing Boost libraries or BOOST_ROOT to the location of
  Boost.
Call Stack (most recent call first):
  CMakeLists.txt:11 (find_package)

这是因为CMake尝试查找libboost_python3.so库，但在Ubuntu中它实际上是libboost_python-py35.so（/usr/lib/x86_64-linux-gnu/libboost_python-py35.so），所以您需要更改该行

find_package(Boost REQUIRED python3)

到

find_package(Boost REQUIRED python-py35)

在文件 src/vision_opencv/cv_bridge/CMakeLists.txt 中进行修改并重新构建包。