無法將cv_bridge與ROS Kinetic和Python3一起使用

Question

我在Ubuntu 14.04上有一個使用ROS indigo和python3的計算機視覺項目，然后我不得不使用ROS動能在Ubuntu 16.04上移動。 在這里我遇到了多個問題：

1）我安裝了opencv，但無法在python3中導入它，錯誤信息為：

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

我想到的只是重命名cv2.so

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

然后我能夠導入cv2並使用它

2）然后我無法導入rospy，但安裝python3-catkin-pkg-modules和python3-rospkg-modules解決了這個問題

3）最后我遇到了cv_bridge的問題，它說：

[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)

我相信問題出在cv_bridge_boost.so文件中。 我也嘗試從https://github.com/ros-perception/vision_opencv構建cv_bridge，但它會自動為python2.7構建，我試圖稍微修改一下CMakeLists.txt以指定python3，但我不知道對CMakeLists有很多經驗，所以它沒有用。 我還嘗試將cv_bridge模塊復制到我的項目文件夾，但它沒有太大變化，它仍然指向cv_bridge_boost.so文件。 另外要提到的是cv_bridge與python2.7一起工作正常，但我的項目需要python3.5。

Answer 1

你是對的，你應該用python3構建cv_bridge。

你可以通過傳球

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

args to cmake。 或者，如果您使用catkin構建包，則可以執行以下步驟：

# `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

和

$ 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
>>> 

如果您遇到下一個錯誤

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)

這是因為CMake試圖找到libboost_python3.so庫，但是在ubuntu中它是libboost_python-py35.so （ /usr/lib/x86_64-linux-gnu/libboost_python-py35.so ），所以你應該libboost_python-py35.so

find_package(Boost REQUIRED python3)

至

find_package(Boost REQUIRED python-py35)

在文件src/vision_opencv/cv_bridge/CMakeLists.txt和rebuild包中。

Answer 2

我的系統中安裝了anaconda3，在使用cv_bridge時遇到了類似的問題。 當我嘗試使用catkin build cv_bridge進行catkin build cv_bridge它會引發錯誤。 我從conda使用python3.7。 我的catkin cofig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

解決方案：我做了幾件事，問題得到了解決。

• 自從anaconda被使用以來，可執行文件和包括導演應該是你當前虛擬環境中的那個。 -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 e
• 當我嘗試使用catkin build cv_bridge時，我遇到了構建問題。 如果您遇到類似問題，請刪除除src之外的所有文件夾。 然后從終端運行catkin_make（確保你出現在catkin_workspace中）。
• 獲取當前工作空間source devel/setup.bash

現在import cv2 from cv_bridge.boost.cv_bridge_boost import getCvType

應該沒有錯誤地工作。