Building / Cross Compiling OpenCV for Linux ARM

This article outlines the steps necessary for building OpenCV for a Linux ARM target. OpenCV is an open-source, cross-platform computer vision and machine vision library.

I cross compiled OpenCV for a Xilinx Zinq ARM system yesterday by more-or-less following the steps outlined in the above document – I had to change a few things to get the build to work. I am documenting the exact steps that I took in case anybody is having trouble (probably future me!).

I started with a fairly clean Ubuntu install on a virtual machine (it already had git installed) , first I installed some build tools, feel free to skip any that you already have:

sudo apt-get install build-essential
sudo apt-get install cmake

Then I installed the GNU ARM tool-chain:

sudo apt-get install gcc-arm-linux-gnueabi
sudo apt-get install g++-arm-linux-gnueabi

This installed version 4.7 of the compilers while the build process calls for version 4.6, to get around this I modified the cmake platform file slightly, see below.

Create a build directory, cd into it and get the OpenCV source from github:

mkdir opencv_build
cd opencv_build
git clone https://github.com/Itseez/opencv.git

To fix the version problem I modified the compiler version in the platform file (this may not be the most correct way to do this but it worked for me!):

I edited this file:

./opencv/platforms/linux/arm-gnueabi.toolchain.cmake

I changed the GCC_COMPILER_VERSION variable’s value from 4.6 to 4.7 to match my installed compiler. I had to edit the file as I wasn’t able to override these variables from the command line.

Now create a sub-directory called build and cd into it:

mkdir build
cd build

And configure the build:

cmake -DSOFTFP=ON  -DCMAKE_TOOLCHAIN_FILE=../opencv/platforms/linux/arm-gnueabi.toolchain.cmake ../opencv

This should complete without errors if you have the compiler that it is looking for installed etc.

Now run ‘make’ and ‘make install’:

make
make install

Make will take a few minutes to run, make install should copy the output files to a subdirectory called ‘install’.

All being well you should now have all the include and lib files that you need to build an OpenCV app for your ARM device.