By default, the official OpenCV Android SDK doesn’t contain the contrib libraries, like Aruco.

prerequisite

• NDK r10e

https://dl.google.com/android/repository/android-ndk-r10e-darwin-x86_64.zip

• Android SDK

Note: please degrade the Android SDK tools version, 25.2.4 is fine for me http://dl-ssl.google.com/android/repository/tools_r25.2.5-macosx.zip Go to ~/Library/Android/sdk, rename tools to tools.bak, then unzip the tools_rxxx.zip to sdk/tools directory. Why? because otherwise, android command has been deprecated)

• opencv 3.3.1

git clone https://github.com/opencv/opencv.git

• opencv_contrib

git clone https://github.com/opencv/opencv_contrib.git

• CMake

brew install cmake ninja ant

How to do it

Assume the following is my unziped directories in my home.

$ ls
opencv
opencv_contrib
android-ndk-r10e

Then run these commands:

$ cd ~/opencv/ && mkdir build
$ cd ~/opencv/platforms/android
$ ./build_sdk.py --ndk_path ~/android-ndk-r10e --sdk_path ~/Library/Android/sdk --extra_modules_path ~/opencv_contrib/modules ~/opencv/build ~/opencv

Go to ~/opencv/build/sdk, you can see all are there.

That’s it. Bingo!