mirror of https://github.com/opencv/opencv.git
Open Source Computer Vision Library
https://opencv.org/
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156 lines
6.1 KiB
156 lines
6.1 KiB
= Android = |
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Android is awesome, and so is OpenCV, so wouldn't it be awesomer if they could work together? Well they can, and its now officially supported in opencv trunk. |
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= quick ubuntu opencv static libs build = |
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* install swig {{{sudo apt-get install swig}}} |
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* unzip the crystax ndk r4 to your home directory http://www.crystax.net/android/ndk-r4.php |
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* svn up your opencv - from https://code.ros.org/svn/opencv/trunk/opencv |
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{{{ |
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cd opencv/android |
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mkdir build |
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cd build |
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cmake .. |
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make |
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}}} |
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= Prerequisites = |
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* swig 1.3 - stable version in your package manager or from cygwin or from http://swig.org/ |
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* crystax ndk r4 - http://www.crystax.net/android/ndk-r4.php - unzip/untar to your home directory for easy cmake locating |
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* android sdk latest - http://developer.android.com/sdk/index.html |
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* ant build system - for compiling android apps on command line |
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* (optional) eclipse android sdk adt plugin and eclipse cdt http://developer.android.com/sdk/eclipse-adt.html |
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* latest code from opencv svn trunk - from https://code.ros.org/svn/opencv/trunk/opencv |
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= android ndk = |
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This will not work with the official release of the android ndk. |
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The official android ndk does not support c++ concepts fully like RTTI, exceptions, and most of the stl. |
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Make sure you use the modified android ndk from crystax available at http://www.crystax.net/android/ndk-r4.php |
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The android ndk, now referred to as the ndk, is the gcc toolchain for android, and is what creates the shared |
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libraries for android that are loadable by android apps through a the Java Native Interface(JNI) |
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Recommended install of the ndk is to unzip it to your home directory |
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For example this is what mine looks like: |
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{{{ |
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erublee@bde:~/android-ndk-r4-crystax$ ls |
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build docs GNUmakefile ndk-build ndk-gdb README.TXT samples sources |
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}}} |
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= Android SDK = |
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Please read the very well documented android sdk getting started instructions - http://developer.android.com/sdk/index.html and at least build and install a hello world app on your Android phone. |
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== Android SDK tips == |
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I always add the android sdk tools directory to my path so i can run the adb from any where. |
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On ubuntu, add the following to your {{{~/.bashrc}}} |
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{{{ |
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export PATH=~/android-sdk-linux_x86/tools:$PATH |
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}}} |
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Install ant so that you can build from command line. |
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Make sure your udev permissions are set for usb debug and that the phone itself is set to allow debugging |
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http://developer.android.com/guide/developing/device.html#setting-up |
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Nexus one users on ubuntu lucid should have the following udev file: |
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{{{ |
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/etc/udev/rules.d/51-android.rules |
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SUBSYSTEM=="usb", SYSFS{idVendor}=="18d1", MODE="0666" |
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}}} |
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see the following blog post on why http://alan.lamielle.net/2010/01/22/nexus-one-usb-in-ubuntu-9-10 |
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= How and What = |
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The android port involves high jacking the existing cmake build files and replacing the define_opencv_module with android specific build commands. |
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In particular the cmake based build creates android ndk build files and calls the android ndk to build opencv. |
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== OpenCV static libs == |
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The main cmake build of opencv generates a static lib for each module and some of the 3rdparty libraries. These can then be linked against in your own android projects. |
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the cmake build will also generate an android-opencv.mk file in the build folder. Include this file in your Android.mk files to link against the static libs. |
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this would go in your Android.mk file. See the docs in the ndk for an explanation of LOCAL_LDLIBS and LOCAL_C_INCLUDES. |
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{{{ |
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#define OPENCV_INCLUDES and OPENCV_LIBS |
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include $(PATH_TO_OPENCV_ANDROID_BUILD)/android-opencv.mk |
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LOCAL_LDLIBS += $(OPENCV_LIBS) |
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LOCAL_C_INCLUDES += $(OPENCV_INCLUDES) |
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}}} |
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== OpenCV shared library == |
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There is an attempt at a library that is more generally useful for android that could also be linked against in your on projects. This project is under |
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opencv/android/android-jni |
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This uses swig to expose some functions to java. Also it implements a live camera preview interface, so that you can have access to the Android camera for live vision apps. |
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== Apps == |
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A few sample apps that use the library are under opencv/android/apps |
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* CVCamera is a complete example that uses the opencv static libs and the android-jni project |
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* Calibration is a stand alone camera calibration app for your Android that is pure java and links against the android-jni project - use this app to make a camera.yml calibration file in your sdcard's home directory |
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* more to come ... |
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= steps = |
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=== Static libs === |
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{{{ |
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cd opencv/android |
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mkdir build |
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cd build |
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cmake .. |
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make |
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}}} |
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this may take a while |
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=== android-jni === |
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After the static libs are built, run make in the android-jni folder |
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{{{ |
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cd opencv/android/android-jni |
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make |
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}}} |
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That creates the swig wrappers and compiles the shared library. |
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now run the ant based java build |
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{{{ |
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sh ./project_create.sh |
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ant debug |
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}}} |
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Now you're ready to use it in a sample |
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=== CVCamera === |
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{{{ |
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cd opencv/android/apps/CVCamera |
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sh build.sh |
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}}} |
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That builds the swig wrappers and shared library. |
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Build the android apk ( the thing that gets installed on the phone ) |
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{{{ |
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sh project_create.sh |
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ant debug |
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}}} |
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Now if everything worked, try to install it. Connect your device and run the following |
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{{{ |
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ant install |
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}}} |
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Run it, press menu to see options - right now it can draw fast, star, and surf feature points on the live preview image. |
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=== Calibration === |
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{{{ |
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sh project_create.sh |
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ant debug |
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ant install |
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}}} |
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To run the app, make sure that the sdcard is not mounted on your computer and point the phone at a calibration pattern and snap away. When you have taken enough chessboards to satisfy yourself |
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press the save button to have the camera calibarted. The calibration will be saved to /sdcard/opencv/calibration.yml |
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Also see this app for how to make a slightly nicer camera ui than CVCamera. |
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=== Troubles === |
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try to edit the local.env.mk file's that get created in CVCamera and android-jni to reflect your system. |
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Also using cmake-gui or ccmake are good options to set up where your ndk directory are. |
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Send questions/comments to Ethan Rublee ethan.rublee@gmail.com |
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= Programming your own apps = |
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Try to look at the samples - like CVCamera, for how to do this. A tutorial may be forth coming. |
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