ubuntu20.04安装opencv4.2 cmake报错

ubuntu20.04安装opencv4.2 cmake报错
参考：https://blog.csdn.net/qq_34256375/article/details/107836051
https://docs.opencv.org/4.2.0/d7/d9f/tutorial_linux_install.html
https://blog.csdn.net/u011622208/article/details/104265206
备注：安装过程尽量看看官方文档

$ cmake -D OPENCV_EXTRA_MODULES_PATH=~/opencv_contrib/modules CMAKE_C_COMPILER=/usr/bin/gcc-5 ..

然后

-- Detected processor: x86_64
-- Looking for ccache - not found
-- Found ZLIB: /usr/lib/x86_64-linux-gnu/libz.so (found suitable version "1.2.11", minimum required is "1.2.3") 
-- Found ZLIB: /usr/lib/x86_64-linux-gnu/libz.so (found version "1.2.11") 
-- IPPICV: Download: ippicv_2019_lnx_intel64_general_20180723.tgz
-- Try 1 failed
-- 
=======================================================================
  Couldn't connect to server from the Internet.
  Perhaps direct connections are not allowed in the current network.
  To use proxy please check/specify these environment variables:
  - http_proxy/https_proxy
  - and/or HTTP_PROXY/HTTPS_PROXY
=======================================================================

CMake Warning at cmake/OpenCVDownload.cmake:202 (message):
  IPPICV: Download failed: 7;"Couldn't connect to server"

  For details please refer to the download log file:

  /home/ye/opencv-4.2.0/build/CMakeDownloadLog.txt

Call Stack (most recent call first):
  3rdparty/ippicv/ippicv.cmake:42 (ocv_download)
  cmake/OpenCVFindIPP.cmake:240 (download_ippicv)
  cmake/OpenCVFindLibsPerf.cmake:12 (include)
  CMakeLists.txt:674 (include)


-- Could not find OpenBLAS include. Turning OpenBLAS_FOUND off
-- Could not find OpenBLAS lib. Turning OpenBLAS_FOUND off
-- Could NOT find Atlas (missing: Atlas_CLAPACK_INCLUDE_DIR) 
-- A library with LAPACK API found.
-- Could NOT find JNI (missing: JAVA_INCLUDE_PATH JAVA_INCLUDE_PATH2 JAVA_AWT_INCLUDE_PATH) 
-- The imported target "vtkParseOGLExt" references the file
   "/usr/bin/vtkParseOGLExt-7.1"
but this file does not exist.  Possible reasons include:

* The file was deleted, renamed, or moved to another location.
* An install or uninstall procedure did not complete successfully.
* The installation package was faulty and contained
   "/usr/lib/cmake/vtk-7.1/VTKTargets.cmake"
but not all the files it references.

-- The imported target "vtkRenderingPythonTkWidgets" references the file
   "/usr/lib/x86_64-linux-gnu/libvtkRenderingPythonTkWidgets.so"
but this file does not exist.  Possible reasons include:
* The file was deleted, renamed, or moved to another location.
* An install or uninstall procedure did not complete successfully.
* The installation package was faulty and contained
   "/usr/lib/cmake/vtk-7.1/VTKTargets.cmake"
but not all the files it references.

-- The imported target "vtk" references the file
   "/usr/bin/vtk"
but this file does not exist.  Possible reasons include:
* The file was deleted, renamed, or moved to another location.
* An install or uninstall procedure did not complete successfully.
* The installation package was faulty and contained
   "/usr/lib/cmake/vtk-7.1/VTKTargets.cmake"
but not all the files it references.

-- The imported target "pvtk" references the file
   "/usr/bin/pvtk"
but this file does not exist.  Possible reasons include:
* The file was deleted, renamed, or moved to another location.
* An install or uninstall procedure did not complete successfully.
* The installation package was faulty and contained
   "/usr/lib/cmake/vtk-7.1/VTKTargets.cmake"
but not all the files it references.

-- Found VTK 7.1.1 (/usr/lib/cmake/vtk-7.1/UseVTK.cmake)
CMake Error at cmake/OpenCVModule.cmake:288 (message):
  No modules has been found: /home/ye/opencv_contrib/modules
Call Stack (most recent call first):
  cmake/OpenCVModule.cmake:370 (_glob_locations)
  modules/CMakeLists.txt:7 (ocv_glob_modules)

-- OpenCV Python: during development append to PYTHONPATH: /home/ye/opencv-4.2.0/build/python_loader
-- Registering hook 'INIT_MODULE_SOURCES_opencv_dnn': /home/ye/opencv-4.2.0/modules/dnn/cmake/hooks/INIT_MODULE_SOURCES_opencv_dnn.cmake
-- opencv_dnn: filter out cuda4dnn source code
-- 
-- General configuration for OpenCV 4.2.0 =====================================
--   Version control:               unknown
-- 
--   Platform:
--     Timestamp:                   2020-08-18T10:16:56Z
--     Host:                        Linux 5.4.0-44-generic x86_64
--     CMake:                       3.16.3
--     CMake generator:             Unix Makefiles
--     CMake build tool:            /usr/bin/make
--     Configuration:               Release
-- 
--   CPU/HW features:
--     Baseline:                    SSE SSE2 SSE3
--       requested:                 SSE3
--     Dispatched code generation:  SSE4_1 SSE4_2 FP16 AVX AVX2 AVX512_SKX
--       requested:                 SSE4_1 SSE4_2 AVX FP16 AVX2 AVX512_SKX
--       SSE4_1 (16 files):         + SSSE3 SSE4_1
--       SSE4_2 (2 files):          + SSSE3 SSE4_1 POPCNT SSE4_2
--       FP16 (1 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
--       AVX (5 files):             + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
--       AVX2 (29 files):           + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2
--       AVX512_SKX (6 files):      + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2 AVX_512F AVX512_COMMON AVX512_SKX
-- 
--   C/C++:
--     Built as dynamic libs?:      YES
--     C++ Compiler:                /usr/bin/c++  (ver 9.3.0)
--     C++ flags (Release):         -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winit-self -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG  -DNDEBUG
--     C++ flags (Debug):           -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wuninitialized -Winit-self -Wsuggest-override -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -fvisibility-inlines-hidden -g  -O0 -DDEBUG -D_DEBUG
--     C Compiler:                  /usr/bin/cc
--     C flags (Release):           -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Winit-self -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -O3 -DNDEBUG  -DNDEBUG
--     C flags (Debug):             -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wuninitialized -Winit-self -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fvisibility=hidden -g  -O0 -DDEBUG -D_DEBUG
--     Linker flags (Release):      -Wl,--gc-sections  
--     Linker flags (Debug):        -Wl,--gc-sections
--     ccache:                      NO
--     Precompiled headers:         NO
--     Extra dependencies:          dl m pthread rt
--     3rdparty dependencies:
-- 
--   OpenCV modules:
--     To be built:                 calib3d core dnn features2d flann gapi highgui imgcodecs imgproc ml objdetect photo python2 python3 stitching ts video videoio
--     Disabled:                    world
--     Disabled by dependency:      -
--     Unavailable:                 java js
--     Applications:                tests perf_tests apps
--     Documentation:               NO
--     Non-free algorithms:         NO
-- 
--   GUI: 
--     GTK+:                        YES (ver 3.24.20)
--       GThread :                  YES (ver 2.64.3)
--       GtkGlExt:                  NO
--     VTK support:                 YES (ver 7.1.1)
-- 
--   Media I/O: 
--     ZLib:                        /usr/lib/x86_64-linux-gnu/libz.so (ver 1.2.11)
--     JPEG:                        /usr/lib/x86_64-linux-gnu/libjpeg.so (ver 80)
--     WEBP:                        /usr/lib/x86_64-linux-gnu/libwebp.so (ver encoder: 0x020e)
--     PNG:                         /usr/lib/x86_64-linux-gnu/libpng.so (ver 1.6.37)
--     TIFF:                        /usr/lib/x86_64-linux-gnu/libtiff.so (ver 42 / 4.1.0)
--     JPEG 2000:                   /usr/lib/x86_64-linux-gnu/libjasper.so (ver 1.900.1)
--     OpenEXR:                     build (ver 2.3.0)
--     HDR:                         YES
--     SUNRASTER:                   YES
--     PXM:                         YES
--     PFM:                         YES
-- 
--   Video I/O:
--     DC1394:                      YES (2.2.5)
--     FFMPEG:                      YES
--       avcodec:                   YES (58.54.100)
--       avformat:                  YES (58.29.100)
--       avutil:                    YES (56.31.100)
--       swscale:                   YES (5.5.100)
--       avresample:                YES (4.0.0)
--     GStreamer:                   YES (1.16.2)
--     v4l/v4l2:                    YES (linux/videodev2.h)
-- 
--   Parallel framework:            pthreads
-- 
--   Trace:                         YES (with Intel ITT)
-- 
--   Other third-party libraries:
--     Lapack:                      NO
--     Eigen:                       YES (ver 3.3.7)
--     Custom HAL:                  NO
--     Protobuf:                    build (3.5.1)
-- 
--   OpenCL:                        YES (no extra features)
--     Include path:                /home/ye/opencv-4.2.0/3rdparty/include/opencl/1.2
--     Link libraries:              Dynamic load
-- 
--   Python 2:
--     Interpreter:                 /usr/bin/python2.7 (ver 2.7.18)
--     Libraries:                   /usr/lib/x86_64-linux-gnu/libpython2.7.so (ver 2.7.18rc1)
--     numpy:                       /usr/lib/python2.7/dist-packages/numpy/core/include (ver 1.16.5)
--     install path:                lib/python2.7/dist-packages/cv2/python-2.7
-- 
--   Python 3:
--     Interpreter:                 /usr/bin/python3 (ver 3.8.2)
--     Libraries:                   /usr/lib/x86_64-linux-gnu/libpython3.8.so (ver 3.8.2)
--     numpy:                       /usr/lib/python3/dist-packages/numpy/core/include (ver 1.17.4)
--     install path:                lib/python3.8/dist-packages/cv2/python-3.8
-- 
--   Python (for build):            /usr/bin/python2.7
-- 
--   Java:                          
--     ant:                         NO
--     JNI:                         NO
--     Java wrappers:               NO
--     Java tests:                  NO
-- 
--   Install to:                    /usr/local
-- -----------------------------------------------------------------
-- 
-- Configuring incomplete, errors occurred!
See also "/home/ye/opencv-4.2.0/build/CMakeFiles/CMakeOutput.log".
See also "/home/ye/opencv-4.2.0/build/CMakeFiles/CMakeError.log".

主要问题是ippicv_2019_lnx_intel64_general_20180723.tgz文件下载失败。
参考官方文档使用
cmake-gui

set full path to OpenCV source code, e.g. /home/user/opencv
set full path to , e.g. /home/user/opencv/build
set optional parameters
run: “Configure”
run: “Generate”

configure之后看红字提示的报错CMakeDownloadLog.txt

想办法下载到ippicv_2019_lnx_intel64_general_20180723.tgz文件，网上有很多

进入/opencv-4.2.0/.cache/ippicv文件夹，把下载到的ippicv_2019_lnx_intel64_general_20180723.tgz文件改成该文件夹下未下载完成的那个文件名，然后删除原来的文件。

重新configure，然后没有红色报错后，generate

然后继续进行后面的步骤

make -j8
sudo make install