一、前言

opencv document : https://docs.opencv.org/master/index.html

tracking 不在 modules中而在 extra modules 中 ,

因此直接下载的opencv_android_sdk\sdk\java\src\org\opencv\中没有tracking ，

无法 import org.opencv.tracking;

https://docs.opencv.org/4.5.0/javadoc/org/opencv/tracking/Tracker.html

因为 tracking等部分功能已经移到opencv_contrib 中，需要单独下载并重新编译

二、编译opencv版本

opencv : https://github.com/opencv/opencv/releases 4.5.0

opencv_contrib : https://github.com/opencv/opencv_contrib/releases 4.5.0

(下载相同版本)

三、方法尝试

方法1.1：linux： https://blog.csdn.net/heiheiya/article/details/80998082

方法1.2 https://www.cnblogs.com/ahfuzhang/p/11069832.html

失败过程略

方法2：BUILD_SDK.PY : https://www.freesion.com/article/3476178517/

python3 build_sdk.py \
            --ndk_path $ANDROID_NDK \
            --sdk_path $ANDROID_SDK \
            --no_samples_build \
            work_dir '/dfsdata2/liuwr5_data/C++/opencv/opencv-4.5.0' \
            --extra_modules_path '/dfsdata2/liuwr5_data/C++/opencv/opencv_contrib/modules'

1）注意 config中要求的ndk与sdk版本：ndk-18-api-level-21.config API 21 安装ndk-r22b sdk-r25.2.3

2）download the Android SDK without Android Studio bundled：https://guides.codepath.com/android/installing-android-sdk-tools#installing-the-android-sdk-via-homebrew

sdkmanager 命令行安装 platforms build-tools platforms-tools

3）手动安装最新版cmake

sudo apt-get install ccache ninju-build

4）设置环境变量

export ANDROID_SDK=/dfsdata2/liuwr5_data/C++/opencv/android-sdk-r25
export PATH=$PATH:$ANDROID_SDK/tools
export ANDROID_NDK=/dfsdata2/liuwr5_data/C++/opencv/android-ndk-r22b

成功！

四、其他网址收藏

Android Studio 中集成Opencv环境（包含opencv_contrib部分）： https://www.cnblogs.com/fx-blog/p/8206737.html

Android Studio 2.2 中利用CAMKE进行OpenCV的NDK开发： https://www.cnblogs.com/fx-blog/p/8215331.html

Windows编译 : https://blog.csdn.net/ezhchai/article/details/80557936

Linux编译 : https://blog.csdn.net/wilson1068/article/details/88768865

报错：

[ 72%] Building CXX object modules/xfeatures2d/CMakeFiles/opencv_xfeatures2d.dir/src/boostdesc.cpp.o
/dfsdata2/liuwr5_data/C++/opencv_android/opencv_contrib-4.5.0/modules/xfeatures2d/src/boostdesc.cpp:654:37:fatal error: boostdesc_bgm.i: No such file or directory
compilation terminated.
modules/xfeatures2d/CMakeFiles/opencv_xfeatures2d.dir/build.make:571: recipe for target 'modules/xfeatures2d/CMakeFiles/opencv_xfeatures2d.dir/src/boostdesc.cpp.o' failed
make[2]: *** [modules/xfeatures2d/CMakeFiles/opencv_xfeatures2d.dir/src/boostdesc.cpp.o] Error 1
CMakeFiles/Makefile2:5970: recipe for target 'modules/xfeatures2d/CMakeFiles/opencv_xfeatures2d.dir/all' failed
make[1]: *** [modules/xfeatures2d/CMakeFiles/opencv_xfeatures2d.dir/all] Error 2
Makefile:149: recipe for target 'all' failed
make: *** [all] Error 2

https://blog.csdn.net/u011736771/article/details/85960300/