OpenCV

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Forewords

This page explains how to (cross-)compile OpenCV 2.1.0 or later for your APF-board.

Pre-requisite

The CMake infrastructure has been integrated in Buildroot since the BR release 2011.02.

The CMake infrastructure is available in armadeus SDK since the armadeus-4.1 release (since it is based on BR release 2011.05).

Note: Using elder armadeus SDK requires having CMake 2.6 or later installed on the host system.

Build OpenCV

Note: The tutorial hereafter (patch and OpenCV configuration) is for the OpenCV 2.1.0 release. This may changes in newer OpenCV releases. Updates are welcome ;-)

1. Setup the CMake toolchain file:
   1. Using armadeus-4.1 SDK or later (or git view): this file is generated by buildroot and is located in armadeus-4.1/buildroot/output/toolchainfile.cmake.
   2. Using armadeus-4.0 SDK or former: the toolchainfile.cmake must be manually edited.
2. Create source and build directories

   mkdir -pv opencv-on-armadeus/{src,build}
   

3. Grab the OpenCV source archive.

   cd opencv-on-armadeus/src && wget http://sourceforge.net/projects/opencvlibrary/files/opencv-unix/2.1/OpenCV-2.1.0.tar.bz2 && tar xvvjf OpenCV-2.1.0.tar.bz2
   

4. Here, you'll have to apply this patch to avoid compilation failed:

   patch -p0 < OpenCV-2.1.0.patch
   

5. Run CMake (generate Makefiles)

   1. cd ~/opencv-on-armadeus/build && cmake -DCMAKE_TOOLCHAIN_FILE:PATH=/path/to/toolchainfile.cmake ../src/OpenCV-2.1.0
      

   2. It will certainly complain about unfound libraries and some other things, so adjust these things running:

      cmake-gui
      

6. Compile OpenCV libraries

   VERBOSE=1 make
   

Note: cmake-gui Click twice on Configure when you change something. When configuring exit without any error, click on Generate to generate Makefiles. If your configuration is too messy, reset it by deleting the cache (File/Delete Cache) or remove the CMakeCache.txt file in the build directory. Don't hesitate to do so if something (eg. paths) is wrong ;) To see the cmake-command that corresponds to the configuration you have just set in cmake-gui: Tools/Show my changes

Available features (for armadeus-4.0 release or former)

CMake looks for all required tool in the path specified in toolchainfile.cmake; therefore, some options, targets, libraries, ... are not available:

• Build:
  • Latex Doc  : Not available in Buildroot
  • New Python support  : Not available (require Python >=2.6, Buildroot provides Python 2.4)
  • Swing Python support : Not available (require Python >=2.6, Buildroot provides Python 2.4)
  • Octave support  : Not available in Buildroot
• Python
  • Executable  : Not found (require Python >=2.6, Buildroot provides Python 2.4)
  • Include dirs.  : Found
  • Library  : Not found (require Python >=2.6, Buildroot provides Python 2.4)
• With
  • V4L  : Disable it (Buildroot provides it, but linker failed)
• OpenCV
  • 3rd party libs.  : You can enable it.

Note: You may need to enable some packages in your Armadeus configuration to get some libraries (libjpeg, libpng and libtiff) found by CMake.

Run OpenCV applications on your APF-board

1. In the build directory, you should find a bin and a lib sub-directories. Copy them (at least the lib directory) on your target.

2. export LD_LIBRARY_PATH=/path/to/the/OpenCVlibdir
   

3. Run your application. You can try cvtest (some tests may fail because of missing resources), it will take a while... a long while ;)

See also

• OpenCV install guide

Appendices

OpenCV-2.1.0.patch

--- OpenCV-2.1.0/3rdparty/flann/constants.h.origin	2010-06-08 01:14:22.171416516 +0200
+++ OpenCV-2.1.0/3rdparty/flann/constants.h	2010-06-08 01:15:06.912417891 +0200
@@ -41,7 +41,7 @@ enum flann_algorithm_t {
 	KMEANS = 2,
 	COMPOSITE = 3,
 	SAVED = 254,
-	AUTOTUNED = 255,
+	AUTOTUNED = 255
 };
 
 enum flann_centers_init_t {
--- OpenCV-2.1.0/3rdparty/flann/flann.h.origin	2010-06-08 01:14:32.588443815 +0200
+++ OpenCV-2.1.0/3rdparty/flann/flann.h	2010-06-08 01:15:06.912417891 +0200
@@ -267,7 +267,7 @@ LIBSPEC int flann_compute_cluster_center
 
 
 #ifdef __cplusplus
-};
+}
 
 
 #include "flann.hpp"
--- OpenCV-2.1.0/3rdparty/include/flann/constants.h.origin	2010-06-08 01:14:54.503416676 +0200
+++ OpenCV-2.1.0/3rdparty/include/flann/constants.h	2010-06-08 01:15:06.912417891 +0200
@@ -41,7 +41,7 @@ enum flann_algorithm_t {
 	KMEANS = 2,
 	COMPOSITE = 3,
 	SAVED = 254,
-	AUTOTUNED = 255,
+	AUTOTUNED = 255
 };
 
 enum flann_centers_init_t {
--- OpenCV-2.1.0/3rdparty/include/flann/flann.h.origin	2010-06-08 01:14:44.672417690 +0200
+++ OpenCV-2.1.0/3rdparty/include/flann/flann.h	2010-06-08 01:15:06.912417891 +0200
@@ -267,7 +267,7 @@ LIBSPEC int flann_compute_cluster_center
 
 
 #ifdef __cplusplus
-};
+}
 
 
 #include "flann.hpp"