OpenCV (Open Source Computer Vision) is a library of programming functions for real time computer vision.

At present, prebuilt binaries/packages are not available for OpenCV on Centos/RHEL 5. Here are the notes from my attempts to get it compiled.

Please make sure you have latest cmake installed from http://www.cmake.org/files/v2.8/cmake-2.8.10.2.tar.gz

To Install OpenCV python modules, you will need python-numpy modules to be installed.

easy_install numpy

Then compile OpenCV using(assuming, your latest python is installed in /usr/local/python-2.7):

cmake -DCMAKE_BUILD_TYPE=RELEASE -DCMAKE_INSTALL_PREFIX=/usr/local -DBUILD_EXAMPLES=ON -DBUILD_NEW_PYTHON_SUPPORT=ON -DINSTALL_PYTHON_EXAMPLES=ON -DPYTHON_EXECUTABLE=/usr/local/python-2.7/bin/python -DPYTHON_INCLUDE_DIR=/usr/local/python-2.7/include -DPYTHON_LIBRARY=/usr/local/python-2.7/lib/libpython2.7.so -DPYTHON_NUMPY_INCLUDE_DIR=/usr/local/python-2.7/lib/python2.7/site-packages/numpy/core/include/ -DPYTHON_PACKAGES_PATH=/usr/local/python-2.7/lib/python2.7/site-packages/

Using BUILD_NEW_PYTHON_SUPPORT fixes the issue seen below:

CMake Warning:
   Manually-specified variables were not used by the project:

   BUILD_PYTHON_SUPPORT

If you get the following Error:

CMake Error at apps/haartraining/CMakeLists.txt:39 (set_target_properties):
set_target_properties called with incorrect number of arguments.

CMake Error at apps/traincascade/CMakeLists.txt:29 (set_target_properties):
set_target_properties called with incorrect number of arguments.

it can be fixed in both files by enclosing ${EXECUTABLE_OUTPUT_PATH} with double quotes (“${EXECUTABLE_OUTPUT_PATH}”)

Then, run make

make

Now, make will throw an error when it tries to compile freak.cpp. To get this compiled, compile it manually (without using any optimization )

cd /home/ram/OpenCV-2.4.3/modules/features2d ; 
/usr/bin/c++ -Dopencv_features2d_EXPORTS -DHAVE_CVCONFIG_H \ 
-DCVAPI_EXPORTS -W -Wall -Wformat -Wundef -Winit-self \
-Wpointer-arith -Wshadow -Wsign-promo -fdiagnostics-show-option \
-Wno-long-long -pthread -fomit-frame-pointer -msse -msse2 -msse3 \
-ffunction-sections -DNDEBUG -DNDEBUG -fPIC \
-I/home/ram/OpenCV-2.4.3/modules/features2d/perf -I/home/ram/OpenCV-2.4.3/modules/features2d/include \
-I/home/ram/OpenCV-2.4.3/modules/highgui/include -I/home/ram/OpenCV-2.4.3/modules/flann/include \
-I/home/ram/OpenCV-2.4.3/modules/imgproc/include -I/home/ram/OpenCV-2.4.3/modules/core/include \
-I/home/ram/OpenCV-2.4.3/modules/ts/include -I/home/ram/OpenCV-2.4.3/modules/features2d \
-I/home/ram/OpenCV-2.4.3/modules/features2d/src -I/home/ram/OpenCV-2.4.3/modules/features2d/test \
-I/home/ram/OpenCV-2.4.3 -o CMakeFiles/opencv_features2d.dir/src/freak.cpp.o \
-c /home/ram/OpenCV-2.4.3/modules/features2d/src/freak.cpp

This should build freak manually, so make will not bother recompiling it anymore. Continue build:

cd /home/ram/OpenCV-2.4.3/
make
make install

This completes OpenCV installation. To build the samples:

export PKG_CONFIG_PATH=/usr/local/lib/pkgconfig
cd /home/ram/OpenCV-2.4.3/samples/c
chmod +x build_all.sh
./build_all.sh

When behind a proxy, Google Analytics Reports module in apache throws a “invalid token” message.

Solution:

The drupal_http_request does not handle corporate proxies well. Here is the custom function that I wrote to fix this exact issue:

Replace drupal_http_request in GA.lib.inc, with this function curl_http_request. It works for me. YMMV

Note: This can be used in place of drupal_http_request

When compiling varnishtop (and other tools) on RHEL/CentOS 5, I came across the following issue:

varnishtop.o: In function `do_curses':
/tmp/varnish-2.1.4/bin/varnishtop/varnishtop.c:223: undefined reference to `initscr'
/tmp/varnish-2.1.4/bin/varnishtop/varnishtop.c:224: undefined reference to `raw'
/tmp/varnish-2.1.4/bin/varnishtop/varnishtop.c:225: undefined reference to `noecho'
/tmp/varnish-2.1.4/bin/varnishtop/varnishtop.c:226: undefined reference to `nonl'
/tmp/varnish-2.1.4/bin/varnishtop/varnishtop.c:227: undefined reference to `stdscr'
......
......
collect2: ld returned 1 exit status
make: *** [varnishtop] Error 1


The issue seems to be with the ncurses library that comes with the standard distribution. So, I installed the ncurses-5.7 libs from source, using:
./configure --with-shared --with-debug --enable-overwrite --with-termlib

and then recompiling/building varnish/varnishtop.

Finding Physical Processors:
$ grep 'physical id' /proc/cpuinfo | sort | uniq | wc -l

Finding Virtual Processors
$ grep ^processor /proc/cpuinfo | wc -l

Finding CPU cores
$ grep 'cpu cores' /proc/cpuinfo

“2″ indicates the two physical processors are dual-core, resulting in 4 virtual processors.
If “1″ was returned, the two physical processors are single-core.

If the processors are single-core, and the number of virtual processors is greater than the number of physical processors, the CPUs are using hyper-threading.

Finding CPU Arch
$ grep flags /proc/cpuinfo | uniq | egrep -o -w "rm|tm|lm"

Under “Flags” section in /proc/cpuinfo, you will find any of the flags “tm” or
“rm” or “lm”

• rm (Real Mode) means it is a 16 bit processor
• tm (Transparent Mode) means it is a 32 bit processor
• lm (Long Mode) means it is a 64 bit processor


RewriteEngine on
RewriteCond %{HTTP_HOST} !^www.your_domain.com$
RewriteRule ^(.*)$ http://www.your_domain.com/$1 [R=301]


Piwik(http://piwik.org/) is open source self-hostable web analytics tool (like omniture or  google analytics). To integrate piwik with mediawiki, I customized the existing Google Analytics mediawiki plugin (http://www.mediawiki.org/wiki/Extension:Google_Analytics_Integration) to work with piwik. To include the extension in your wiki,
unzip the file, and deploy the piwik.php extension file into WIKI_INSTALL_DIR/extensions/. Then include the file in your LocalSettings.php, using:

require_once("extensions/piwik.php");


Download piwik extension