Update August 2015:

Eclipse support has ended. Support for the NDK is in preview in Android Studio 1.3 which means soon you will be able to use Android Studio for OpenCV.

Download before the Hackathon

Since the hackathon usually has overloaded wifi you should try to download these files if you know you will be hacking on OpenCV...

Step 0 get SDKs:

Set up Android SDK for your Eclipse, if you dont already have this set up then this project may be a bit over your head... The complete instructions are all on this page: http://developer.android.com/sdk/eclipse-adt.html#installing

Be sure to complete the sdk set up before going to the hackathon because you could need to download around 1 gig (which is pretty much impossible at most hackathons)...

WATCHOUT: dont download all the SDKs, just get the latest.

WATCHOUT: If you have IceCream Sandwich 4.0 there was a problem that OpenCV would give you a black screen. 

Step A:

Install the C++ Development Toolkit in your Eclipse

Step B:

Download the Android NDK

http://developer.android.com/sdk/ndk/index.html

Step C:

Download the OpenCV bin for Android

http://sourceforge.net/projects/opencvlibrary/files/opencv-android/2.3.1/OpenCV-2.3.1-android-bin.tar.bz2/download

Day of The Hackathon: Setup this sample project

Step 1:

Fork this repository into your GitHub account, if you're familiar with GitHub. OR $ git clone https://github.com/AndroidImageProcessing/AndroidOpenCVforHackathons.git Step 2:

Now you can Import the project

Import>>General >>Existing project into workspace>>Browse to AndroidOpenCVforHackathons/android

Step 3:

Create an external builder following these instructions in the OpenCV tutorial http://opencv.itseez.com/doc/tutorials/introduction/android_binary_package/android_binary_package_using_with_NDK.html#theory-how-to-build-android-application-having-c-native-part-from-eclipse

Step 4:

In the Builder created in Step 3, add an Environment Variable on the 3rd tab. Sample var:

OPENCV_PACKAGE_DIR

Sample value:

/Users/yourname/opencv/OpenCV-2.3.1-android-bin

Step 5:

Clean and Run

You should see the Camera view with red lines around contrasts, green circles around circles, and cyan lines under circles larger than 10px wide.

Step 6:

Figure out how it works, by quickly looking at the diffs in the issues of Milestone UpAndRunning:

https://github.com/AndroidImageProcessing/AndroidOpenCVforHackathons/issues?sort=created&direction=desc&state=closed&milestone=1

Step 7:

Modify the code to suit your needs, send us pull requests if you want to help. After a bit of hacking you can check out the code in the issues of Milestone Debugging OpenCV in Android C++

https://github.com/AndroidImageProcessing/AndroidOpenCVforHackathons/issues?milestone=2&state=closed

Step 8:

If you need some more Android code, there are samples to adapt to suit your needs (Bluetooth, services, Rest etc). Just create a new Android Project and click the checkbox from Sample code, you will get a list to choose from.

Step 9:

Spread the joy...

Windows :

You might need to install drivers for the Android device.

Visual Studio Users:

You can compile and run Android from the command line, or just download Eclipse (its about 130MB and works similarily to Visual Studio). There's garenteed to be Eclipse users at the hackathon, don't be shy, ask around to help yourself get set up. After you're set up you only need three things: clean, debug, run.

Full Instructions: From Zero to Eclipse to Android to Android NDK to OpenCV

Assumptions:

• We are going to install the NDK under BASE_DIR; something like: BASE_DIR=/home/amir/Android
  mkdir -p ${BASE_DIR}
• JDK is already installed
• Eclipse is already installed
  cd ${BASE_DIR}
  tar xzvf eclipse-jee-indigo-SR1-linux-gtk.tar.gz

1. Installing the ADT Plugin for Eclipse
   ( Based on http://developer.android.com/sdk/eclipse-adt.html#installing )
   1.1. Start Eclipse, then select Help > Install New Software....
   1.2. Click Add, in the top-right corner.
   1.3. In the Add Repository dialog that appears, enter "ADT Plugin" for the Name and the following URL for the Location:
   https://dl-ssl.google.com/android/eclipse/
   1.4. Click OK
   1.5. In the Available Software dialog, select the checkbox next to Developer Tools and click Next.
   1.6. In the next window, you'll see a list of the tools to be downloaded. Click Next.
   1.7. Read and accept the license agreements, then click Finish.
   1.8. When the installation completes, restart Eclipse.

2. Configuring the SDK
   2.1. In the "Welcome to Android Development" window, select "Install new SDK"
   Note: Personally, I prefer to use a sub-directory of ${BASE_DIR} as "Target Location"
   Note: In order to "Configuring the ADT Plugin": Select Window > Preferences... to open the Preferences panel then select Android from the left panel.

3. Getting the NDK
   ( Based on http://developer.android.com/sdk/ndk/index.html )
   3.1. download the NDL from http://developer.android.com/sdk/ndk/index.html
   wget -c http://dl.google.com/android/ndk/android-ndk-r7-linux-x86.tar.bz2
   3.2. Extract the android-ndk-.tar.gz file:
   tar xjvf android-ndk-r7-linux-x86.tar.bz2

4. Getting the OpenCV package for Android development
   ( Based on http://opencv.itseez.com/doc/tutorials/introduction/android_binary_package/android_binary_package.html#get-the-opencv-package-for-android-development )
   4.1. Go to the http://sourceforge.net/projects/opencvlibrary/files/opencv-android/ and download the latest available version. Currently it is OpenCV-2.3.1-android-bin.tar.bz2
   4.2. Extract the package
   tar xjvf OpenCV-2.3.1-android-bin.tar.bz2

5. Importing the android part of "Bacteria Detecto-Droid" into workspace.
   5.1. File menu -> New Android project -> Create project from existing source
   5.2. location is /AndroidBacteriaImageProcessing/android

6. Build the application from Eclipse
   (Based on http://opencv.itseez.com/doc/tutorials/introduction/android_binary_package/android_binary_package_using_with_NDK.html#theory-how-to-build-android-application-having-c-native-part-from-eclipse )
   6.1. Navigate to Package Explorer window and expand your project having JNI resources.
   6.2. Right click on your project in Package Explorer window and select Properties.
   6.3. In the Properties dialog select Builders menu and press the New... button:
   http://opencv.itseez.com/_images/eclipse_builders.png
   6.4. In the resulting dialog select the Program type and press OK button:
   http://opencv.itseez.com/_images/eclipse_builder_types.png
   6.5. In the Main tab fill the following fields:
   6.5.1. Name (as you like)
   6.5.2. Location - full path to ndk-build tool: Just put full path to ndk-build into this filed.
   6.5.3. Working Directory - put path to your project into this field. Instead of hardcoding full path you can click Browse Workspace... button and select your project.
   http://opencv.itseez.com/_images/eclipse_edit_configuration_main.png
   6.6. Go to the Refresh tab and select both Refresh resources upon completion and Recursively include sub-folders.
   6.6.1. Next set the Specific resources option and click Specify resources... button:
   http://opencv.itseez.com/_images/eclipse_edit_configuration_refresh.png
   6.7. Go to the Environment tab and add OPENCV_PACKAGE_DIR Variable with a Value equal to ${BASE_DIR}
   6.8. Select libs folder under your project and click Finish:
   http://opencv.itseez.com/_images/eclipse_edit_configuration_specify_resources.png
   6.9. Go to the last tab Build options. Make sure that all checkboxes are set as shown on the next screen:
   http://opencv.itseez.com/_images/eclipse_edit_configuration_build_options.png
   6.10. Next, click the Specify resources... button.
   6.11. Select jni folder of your project and click the Finish button:
   http://opencv.itseez.com/_images/eclipse_edit_configuration_build_resources.png
   6.12. Finally press OK in the builder configuration and project properties dialogs. If you have automatic build turned on then console showing build log should appear:
   http://opencv.itseez.com/_images/eclipse_NDK_build_success.png

NOTE: If you are running an x86 system, you might get the following error:
${BASE_DIR}/android-ndk-r7/prebuilt/linux-x86/bin/awk: ${BASE_DIR}/android-ndk-r7/prebuilt/linux-x86/bin/awk: cannot execute binary file
Just link the awk from the NDL to the awk of your distro:
mv ${BASE_DIR}/android-ndk-r7/prebuilt/linux-x86/bin/awk{,.orig}
ln -s which awk ${BASE_DIR}/android-ndk-r7/prebuilt/linux-x86/bin/awk