Python 如何构建和安装OpenCV 4.0？

首先，我想说我正在学习，所以有很多事情我不知道

我使用的Jetson TX1已经与JetPack 3.3一起成像

该板使用Ubuntu 16.04

我安装了cmake 3.13.4。我安装了Python3.7（包括Python2.7（默认）/Python3/Python3.5/Python3.7）

我使用命令python3.7-mpinstallnumpy。它表明

Successfully installed numpy-1.16.1

我这里有个问题：如何找到numpy的安装位置？当我使用ls命令查看/usr/local/lib/python3.7/dist-packages时，它显示为空

当我第一次尝试构建openCV时，我得到了这个

Python 2:
    Interpreter:                 /usr/bin/python2.7 (ver 2.7.12)
    Libraries:                   /usr/lib/aarch64-linux-gnu/libpython2.7.so (ver 2.7.12)
    numpy:                       /usr/lib/python2.7/dist-packages/numpy/core/include (ver 1.11.0)
    packages path:               lib/python2.7/dist-packages

  Python 3:
    Interpreter:                 /usr/bin/python3 (ver 3.5.1)

我想使用Python3.7来构建openCV。我对cmake没有太多经验，但我知道我可以在使用cmake命令行时通过定义参数来更改文件“CMakeLists.txt”中的参数

我在这里有个问题：是否有其他方法来定义这些参数，这样我就不必每次使用cmake构建时都在命令行中包含这些参数

然后我用下面的命令行

sudo cmake -D ENABLE_PRECOMPILED_HEADERS=OFF -D WITH_OPENCL=OFF -D WITH_CUDA=OFF -D WITH_CUFFT=OFF -D WITH_CUBLAS=OFF -D CMAKE_BUILD_TYPE=RELEASE -D CMAKE_INSTALL_PREFIX=/usr/local -D INSTALL_PYTHON_EXAMPLES=OFF -D INSTALL_C_EXAMPLES=OFF -D PYTHON3_EXECUTABLE=/usr/bin/python3.7 -D PYTHON3_LIBRARIES=/usr/lib/aarch64-linux-gnu/libpython3.7m.so -D PYTHON3_NUMPY_INCLUDE_DIRS=/usr/lib/python3.7/dist-packages/numpy/core/include -D PYTHON_DEFAULT_EXECUTABLE=/usr/bin/python3.7 -D BUILD_EXAMPLES=OFF ..

我得到

Python 3:
--     Interpreter:                 /usr/bin/python3.7 (ver 3.5.2)
--     Libraries:                   /usr/lib/aarch64-linux-gnu/libpython3.7m.so (ver 3.5.2)
--     numpy:                       /usr/lib/python3.7/dist-packages/numpy/core/include (ver 1.16.1)
--     packages path:               lib/python3.5/dist-packages
-- 
--   Python (for build):            /usr/bin/python3.7

我这里有个问题：Python 3.7之后的3.5.2版是什么？我不知道为什么包路径指向Python3.5。没有libpython3.7，所以我选择了我找到的libpython3.7m.so。这是正确的吗

然后我用

sudo make -j4

最后，我收到以下错误消息：

[ 98%] Building CXX object modules/python3/CMakeFiles/opencv_python3.dir/__/src2/cv2.cpp.o
/mnt/data/Software/opencv/modules/python/src2/cv2.cpp:39:33: fatal error: numpy/ndarrayobject.h: No such file or directory
compilation terminated.
modules/python3/CMakeFiles/opencv_python3.dir/build.make:62: recipe for target 'modules/python3/CMakeFiles/opencv_python3.dir/__/src2/cv2.cpp.o' failed
make[2]: *** [modules/python3/CMakeFiles/opencv_python3.dir/__/src2/cv2.cpp.o] Error 1
CMakeFiles/Makefile2:3371: recipe for target 'modules/python3/CMakeFiles/opencv_python3.dir/all' failed
make[1]: *** [modules/python3/CMakeFiles/opencv_python3.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
[ 98%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/opencl/perf_motempl.cpp.o
[ 98%] Building CXX object modules/video/CMakeFiles/opencv_test_video.dir/test/test_estimaterigid.cpp.o
[ 98%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/opencl/perf_optflow_farneback.cpp.o
[ 98%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/opencl/perf_optflow_pyrlk.cpp.o
[ 98%] Building CXX object modules/video/CMakeFiles/opencv_test_video.dir/test/test_kalman.cpp.o
[ 98%] Linking CXX executable ../../bin/opencv_test_calib3d
[ 98%] Built target opencv_test_calib3d
[ 99%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/perf_bgfg_knn.cpp.o
[100%] Building CXX object modules/video/CMakeFiles/opencv_test_video.dir/test/test_main.cpp.o
[100%] Building CXX object modules/video/CMakeFiles/opencv_test_video.dir/test/test_optflowpyrlk.cpp.o
[100%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/perf_bgfg_mog2.cpp.o
[100%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/perf_disflow.cpp.o
[100%] Linking CXX executable ../../bin/opencv_test_video
[100%] Built target opencv_test_video
[100%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/perf_ecc.cpp.o
[100%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/perf_main.cpp.o
[100%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/perf_optflowpyrlk.cpp.o
[100%] Building CXX object modules/video/CMakeFiles/opencv_perf_video.dir/perf/perf_variational_refinement.cpp.o
[100%] Linking CXX executable ../../bin/opencv_perf_video
[100%] Built target opencv_perf_video
Makefile:162: recipe for target 'all' failed
make: *** [all] Error 2

---

如何解决这些问题？

以下是一些答案

您可以通过以下方式获得Numpy安装路径和版本：

import numpy as np

print(np.__path__)
'/usr/local/lib/python3.7/site-packages/numpy'

print(np.__version__)
'1.15.1

您还可以使用

pip

获取安装目录：

pip show numpy

样本输出

Name: numpy
Version: 1.15.1
Summary: NumPy: array processing for numbers, strings, records, and objects.
Home-page: http://www.numpy.org
Author: Travis E. Oliphant et al.
Author-email: None
License: BSD
Location: /usr/local/lib/python3.7/site-packages
Requires: 
Required-by: tifffile, scipy, scikit-learn, PyWavelets, numexpr, numba, matplotlib, imageio 

---

通常情况下，您不应将

sudo

用于

cmake

，而只应：

cmake ...

如果您想避免键入所有开关，我通常在所有的OpenCV内容和

$HOME/scripts

中制作一个shell脚本，并将所有开关保存在那里：

#!/bin/bash

cd $HOME/OpenCV/build/somewhere

cmake -D WITH_OPENCL=OFF -D WITH_CUDA=OFF -D CMAKE_BUILD_TYPE=RELEASE ..

---

避免将

sudo

用于

make

，首选：

make -j 4

---

您确定要构建自己的python版本的opencv，而不是只安装opencv 4.0的python包吗？请在每个问题的帖子上回答一个问题。错误消息是关于缺少头文件

numpy/ndarrayobject.h

。您的numpy安装中是否有此文件？非常感谢您的帮助。我使用sudo的原因是我将opencv的下载源文件存储在与Jetson板连接的ssd上。作为一个好的实践，我应该将这些文件存储在主硬盘而不是外部硬盘中吗？我按照你说的做，并且numpy位于/home/ubuntu/.local/lib/python3.7/site packages/下。这是否意味着它停留在错误的位置？对不起，我不能回答你的任何问题-这在很大程度上取决于你的项目设置。你想在CUDA上使用它吗？