Two important courses to follow

(1) Scalable Machine Learning


(2) Introduction to Big Data

zip a folder from Konsole quick

zip MyFolder quick!

$zip -r GiveAnyName.zip MyFolder

Installing OpenCV in Linux

Install dependecies:

$sudo apt-get install build-essential libgtk2.0-dev libjpeg-dev libtiff4-dev libjasper-dev libopenexr-dev cmake python-dev python-numpy python-tk libtbb-dev libeigen2-dev yasm libfaac-dev libopencore-amrnb-dev libopencore-amrwb-dev libtheora-dev libvorbis-dev libxvidcore-dev libx264-dev libqt4-dev libqt4-opengl-dev sphinx-common texlive-latex-extra libv4l-dev libdc1394-22-dev libavcodec-dev libavformat-dev libswscale-dev

$mkdir OpenCV
$cd OpenCV
$git clone https://github.com/Itseez/opencv.git
$cmake CMakeLists.txt
$make
$sudo make install


Make a file under /etc.ld.so.conf.d folder. Name it opencv.conf
Write /usr/local/lib/ and save the file.

$sudo gedit /etc/ld.so.conf.d/opencv.conf
$sudo ldconfig -v

Set the system variables:

$export LD_LIBRARY_PATH=/usr/local/lib/:$LD_LIBRARY_PATH
$sudo ldconfig

$export LD_LIBRARY_PATH=~/opencv/OpenCV-2.0.3/release/:$LD_LIBRARY_PATH
$sudo ldconfig

$sudo gedit /etc/bash.bashrc

Type this to the last line of bash.bashrc:

PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/usr/local/lib/pkgconfig
export PKG_CONFIG_PATH

Installing LIBLAS in Linux

Start with installing GDAL, Libgeotiff and Laszip libraries which will be necessary to build LIBLAS.

Installing GDAL (this might take an hour):

$sudo apt-get install build-essential python-all-dev
$wget http://download.osgeo.org/gdal/gdal-1.9.0.tar.gz
$tar xvfz gdal-1.9.0.tar.gz
$cd gdal-1.9.0
$./configure --with-python
$make
$sudo make install    

Installing Libgeotiff:

sudo apt-get install proj proj-bin proj-data libproj-dev libtiff4-dev libgeotiff-dev libgdal1-dev gdal-bin python-gdal libgdal1-1.7.0

Installing Laszip:

cd /opt/source
wget http://download.osgeo.org/laszip/laszip-2.1.0.tar.gz
tar xvfz laszip-2.1.0.tar.gz
cd laszip-2.1.0
mkdir build
mkdir cmake_build
cd cmake_build
# run cmake
cmake .. -DCMAKE_INSTALL_PREFIX=/opt/source/laszip-2.1.0/build
# compile
make -j$threads
# install into build dir
make install

Finally now you can download LIBLAS source codes and install by typing:

$ git clone git://github.com/libLAS/libLAS.git liblas
$ cd liblas
$ mkdir makefiles
$ cd makefiles
$ cmake -G "Unix Makefiles" ../
$ make

Compile the first PCL code on linux (write pcd)

Source code:

#include <iostream>
#include <pcl/io/pcd_io.h>
#include <pcl/point_types.h>

int
  main (int argc, char** argv)
{
  pcl::PointCloud<pcl::PointXYZ> cloud;

  // Fill in the cloud data
  cloud.width    = 5;
  cloud.height   = 1;
  cloud.is_dense = false;
  cloud.points.resize (cloud.width * cloud.height);

  for (size_t i = 0; i < cloud.points.size (); ++i)
  {
    cloud.points[i].x = 1024 * rand () / (RAND_MAX + 1.0f);
    cloud.points[i].y = 1024 * rand () / (RAND_MAX + 1.0f);
    cloud.points[i].z = 1024 * rand () / (RAND_MAX + 1.0f);
  }

  pcl::io::savePCDFileASCII ("test_pcd.pcd", cloud);
  std::cerr << "Saved " << cloud.points.size () << " data points to test_pcd.pcd." << std::endl;

  for (size_t i = 0; i < cloud.points.size (); ++i)
    std::cerr << "    " << cloud.points[i].x << " " << cloud.points[i].y << " " << cloud.points[i].z << std::endl;

  return (0);
}


make CMakeLists.txt file which contains:

cmake_minimum_required(VERSION 2.8 FATAL_ERROR)

project(pcd_write)

find_package(PCL 1.2 REQUIRED)

include_directories(${PCL_INCLUDE_DIRS})
link_directories(${PCL_LIBRARY_DIRS})
add_definitions(${PCL_DEFINITIONS})

add_executable (pcd_write pcd_write.cpp)
target_link_libraries (pcd_write ${PCL_LIBRARIES})


> cmake CMakeLists.txt
> make
> ./pcd_write

Install Qt on Linux (Ubuntu)

wget http://download.qt-project.org/official_releases/qt/5.0/5.0.2/qt-opensource-linux-x64-1.6.0-5-online.run

chmod +x qt-opensource-linux-x64-1.6.0-5-online.run

./qt-opensource-linux-x64-1.6.0-5-online.run

Pop-up screen will appear!

Select .pro extension project file and apply settings you want.

Check Qt Version

qmake -version

Shows qt and qmake versions.

Compile and Call HelloWorld with G++

compile main.cpp:

g++ -Wall -W -Werror main.cpp -o MyHelloWorld (gcc is C compiler, g++ is C++ compiler)

OR

g++ main.cpp


It generates "a.out"

Call the program;

./a.out

Check Ubuntu Version

lsb_release -a

Installing PCL on Ubuntu

sudo apt-get install cmake (if cmake is not installed yet)
sudo apt-get update
sudo apt-get install git (if git is not installed yet)

git clone https://github.com/PointCloudLibrary/pcl.git pcl-trunk

ln -s pcl-trunk pcl

mkdir release

(Go to PCL Folder)
cmake -DCMAKE_BUILD_TYPE=NONE -DBUILD_GPU=ON -DBUILD_apps=ON -DBUILD_examples=ON

make

sudo make install

Call C++ Function in Matlab

mex -setup %choose compiler
mex mycode.c %call the function


If you need to add other cpp files and lib files while compiling in Matlab:

mex cpp-file-for-matlab.cpp ../addthis.cpp ../addthat.cpp -laddlibrary

PCL Concavehull Fails

...with message saying "The initial hull is narrow (cosine of min. angle is 0.999999999999998). A coplanar point may lead to a wide facet..."

It stops complaining when I set the concavehull dimensions to 2, instead of letting the function decide by itself. It is done by adding the following line;

chull.setDimension(2);

Write C++ Code Process Time on Console

#include <time.h>
time_t start,end;
time (&start);
.
.
.
<code>
.
.
.
time (&end);
double dif = difftime (end,start);
cout<< "Elasped time is " << dif <<" seconds." << "\n" << endl;

File Cannot Be Found - Lovely Crash

...instead of crashing without any error messages

std::ifstream ifs (mystr, std::ios::in | std::ios::binary);

if (ifs.is_open()) {
        cout<<"The file is read successfully! :)"<<endl;}
else {
        // show message:
        cout << "Error opening file!"<<endl;
        cout << "The file cannot be found in the given path."<<endl;
        cout<< "The program will be closed." <<endl;
        system("PAUSE") ;
        exit(EXIT_FAILURE);
 }

Add Environment Variables in C++ Code

char *shell;


/* Get the path of the current shell to start it later */
shell = getenv("SHELL");
if (shell == NULL) {
    fprintf(stderr, "Error eding SHELL env. var.\n");
    return 1;
}       

/* Overwrite env. var. PATH */
if (setenv("PATH", "/usr/bin", 1) < 0) {
    fprintf(stderr, "Error setting env. var.\n");
    return 1;
}

Check also: http://linuxconfig.org/set-and-get-environmental-shell-variable-using-c 

Saving EPS Images in Matlab

Matlab imwrite function does not work for saving EPS format (though some comments on internet say that it is possible by sending the color values to a colormap). One very simple solution is using;

im = imread('image.png');
figure, imshow(im);
print -depsc image2.eps