如何构建和安装 OpenCV 4.0？

Question

首先我想说我正在学习，所以我不知道的东西很多。

我正在使用已使用 JetPack 3.3 进行映像的 Jetson TX1

开发板使用 Ubuntu 16.04

我安装了 cmake 3.13.4。我安装了 Python 3.7（包括 Python 2.7（默认）/Python3/Python3.5/Python 3.7）。

我使用命令 python3.7 -m pip install numpy。它显示了

Successfully installed numpy-1.16.1

我有问题：如何找出 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。

我第一次尝试构建openCV，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，但我知道我可以通过在使用cmake命令行时定义参数来更改文件“CMakeLists.txt”中的参数。

我有一个问题：是否有另一种方法来定义这些参数，这样我就不必在每次使用 cmake 构建时都将这些参数包含在命令行中？

然后我在命令行下面使用了

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 ..

我明白了

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

我有个问题：Python 3.7 之后的 3.5.2 版本是什么？我不确定为什么包路径指向 Python 3.5。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？

Answer 1

这里有一些答案...

您可以通过以下方式获取 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

你也可以用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 

---

一般情况下，您不应将sudo 用于cmake，而只需：

cmake ...

如果您想避免键入所有开关，我通常会在所有 OpenCV 内容和 $HOME/scripts 中创建一个 shell 脚本 outside，并将所有开关保留在那里：

#!/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，更喜欢：

make -j 4