OpenCV 3.1.0 install on Jetson TX1

I used following references.

  • Installation of opencv-3.1.0 on Jetson TX1 [here]
  • Installing OpenCV 3.1.0 [here]
  • minhoolee/ [here]
  • dselivanov/scripts-ubuntu-debian [here]

Uninstall the current OpenCV

  • $ sudo rm -rf /usr/local/include/opencv
  • $ sudo rm -rf /usr/local/include/opencv2
  • $ suro rm -rf /usr/local/lib/python2.7/dist-packages/cv2.*
  • $ suro rm -rf /usr/local/lib/python3.5/dist-packages/cv2.*
  • $ sudo rm /usr/local/lib/libopencv_*

You need to change the Python version numbers if you are using different ones.

Keep Ubuntu up to date

  • $ sudo apt-get -y update
  • $ sudo apt-get -y upgrade
  • $ sudo apt-get -y dist-upgrade
  • $ sudo apt-get -y autoremove

Install development libraries

  • # Add universal repository to Ubuntu
  • $ sudo apt-add-repository universe
  • $ sudo apt-get update
  • # Some general development libraries
  • $ sudo apt-get install -y build-essential make cmake cmake-curses-gui g++
  • # libav video input/output development libraries
  • $ sudo apt-get install -y libavformat-dev libavutil-dev libswscale-dev
  • # Video4Linux camera development libraries
  • $ sudo apt-get install -y libv4l-dev
  • # Eigen3 math development libraries
  • $ sudo apt-get install -y libeigen3-dev
  • # OpenGL development libraries (to allow creating graphical windows)
  • $ sudo apt-get install -y libglew1.6-dev
  • # GTK development libraries (to allow creating graphical windows)
  • $ sudo apt-get install -y libgtk2.0-dev
  • # Install unzip and wget
  • $ sudo apt-get install -y unzip wget

Download and install OpenCV

  • # Download
  • $ cd ~/Downloads
  • $ wget
  • # Unzip
  • $ unzip
  • $ rm
  • # Prepare for building
  • $ cd opencv-3.1.0
  • $ mkdir build $ cd build
  • # Building
  • $ make -j4
  • $ sudo make install
  • # Setup
  • $ sudo /bin/bash -c ‘echo “/usr/local/lib” > /etc/’
  • $ sudo ldconfig

OpenCV issues in Anaconda

When an error message is shown from a python code using cv2 (opencv), the message is most likely misleading. The message is saying nothing but something is wrong. All the details in the message are not what you need to do to fix the problem.

I had issues with VideoCapture and imshow. The error messages look explanatory but they are not. All problems were stemmed from a python wrapper package that I installed through pip.

$pip uninstall opencv-python

Your conda must have one opencv version. In my case, the version is 3.2.0 that was built from source code where I enabled FFMPEG to fix VideoCapture problem.


C scanf with comma separated values.

Unlike scanf function family in MATLAB, C scanf doesn’t consider the comma(,) as a delimiter for the specifier “%s.”

Let’s say we have a data file as follows.

Spiderman,Parker,99<br />Superman,Ken,89<br />Batman,Wayne,79

The following code will not work. The variable “first_name” will have the whole line “Spiderman,Parker,99” since it thinks there is no delimiter in the line.

char first_name[50], last_name[50];<br />int grade;<br />FILE *fp = fopen("data.csv", "r");<br />fscanf(fp, "%s,%s,%d\n", first_name, last_name, &amp;grade);

Here is a way to make scanf functions think the comma (,) is a delimiter.

fscanf(fp, "%[^,],%[^,],%d\n", first_name, last_name, &amp;grade);

fscanf in MATLAB

Unlike in C/C++, fscanf in MATLAB repeats the scanning as long as the formatted text matches. It is convenient but also confusing sometimes.

For example, in a text file there are lines as follows.

Image Width Height: 800, 600
Red X Y Radius: 200, 300, 300
Green X Y Radius: 300, 400, 200
Blue X Y Radius: 500, 500, 150

We can read the first line using
dim = fscanf(fid, '%*s %*s %*s %d, %d\n');             (a)

A problem arises after this scanning since it tries to scan the next line as well with the format that is given. So even if you try to read the next line with the fscanf (b), the scanning will fail since the fscanf in (a) tries to scan the next line.
redc = fscanf(fid, '%*s %*s %*s %*s %d, %d, %d\n');    (b)

So in this specific case, it is better to use the followings.
dim  = fscanf(fid, 'Image Width Height: %d, %d\n');
redc = fscanf(fid, 'Red X Y Radius: %d, %d, %d\n');
grnc = fscanf(fid, 'Green X Y Radius: %d, %d, %d\n');
bluc = fscanf(fid, 'Blue X Y Radius: %d, %d, %d\n');

There are better ways but this would be quick fix.

No Console Output in Eclipse with CDT in Windows

In Windows the Console doesn’t display any output from printf. Let’s see an example.

int main(void) 
    int i;

    printf("Enter a number: ");
    scanf("%d", &amp;i);
    printf("You entered %d\n", i);
    return EXIT_SUCCESS;

The text “Enter a number: ” is not shown in the Console windows of Eclipse with CDT. This is due to the fact all the stdout and stderr ouputs in Windows are buffered. So we can simply flush stdout and stderr everytime you use printf. But it is not practical solution. You may add these two lines of code in the first part of your main function.

  • setvbuf(stdout, NULL, _IONBF, 0);
  • setvbuf(stderr, NULL, _IONBF, 0);

These lines enforce stdout/stderr not to have buffers which means that all the output will be happening as soon as it takes place. One serious problem of this solution is that the program will be crashed if you start the debugger and try to step over any of printfs. So in the Debug mode, starting a new command prompt console is a good idea. Let’s me summary this workaround.

Use setvbuf for Run mode

Put this function in your main function in the first place.

void set_std_buffer_off()
    setvbuf(stdout, NULL, _IONBF, 0);
    setvbuf(stderr, NULL, _IONBF, 0);
int main(void)
    // turn off the std buffering

    // start your own code.

You now see outputs from printfs in your code when you run the program.

Debug mode

For the debug mode, use GDB command file.

Create a text file and named it as “gdbinit.txt” The file name is not important anyway. You may use any proper name. Open the text file and put this single line into the file and save it.

<span style="line-height:1.5em">set new-console on</span>

This line simply means that new console will be started when the debugger starts a debugging session.

Open “Preferences” (Window > Preferences). Set the text file for “GDB command file:” in C/C++ –> Debug –> GDB. Click the “Apply” button and the “OK” button.

Try to debug your program. Then you will see a command prompt when the debugger starts. All outputs and inputs will be happening in the new command prompt without having any troubles.

Using Eclipse with CDT in Windows

Unlike in Mac OS X, it is harder to install Eclipse with CDT in Windows than it looks. This is partially because the Windows OS does not have Java Runtime Environment as default settings. Another problem is that there are two versions, 32-bit and 64-bit, under the same name of the OS. x64-base processors can have either 32-bit OS or 64-bit OS.

Windows 32-bit or 64-bit?

First thing first. Make sure that what system type of Windows you are using. If your PC is pretty new, most likely you have 64-bit Windows. If not, it could be 32- or 64-bit. One simple way to find out which version you are using is to check the “Program Files” folder name. If your system has “Program Files (x86)” along with “Program Files” then your OS is for 64-bit. You may open Control Panel to see the version. The “System type:” in “System and Security->System” tells 64-bit OS or 32-bit OS. Again using x64-bit based processor does not guarantee that the OS type is 64-bit.

Java Runtime Environment

Eclipse is an executable program written in Java and built for Java. Java executables need Java Virtual Machine. Java Runtime Environment or JRE is a basic package to run Java programs. There are several “Editions” in Java. Java SE (Standard Edition) is good for Java applications on desktops and servers. You may find Java “Development” Kit, or JDK while you are googling Java SE Download. This is for Java Developers and includes JRE. We do not need this version because we just want to run a Java program, Eclipse. Download one “jre” according to your OS type. x64  means it is for Windows 64-bit OS. x86 is for Windows 32-bit OS. Install it. Clear check boxes when the Java Setup asks to install something along with Java unless you really really really want to install the toolbar for your Web browsers.


The next step is to install Minimalists for GNU for Windows or MinGW. This is for someone who wants to use the GNU Compiler Collection to develop native Windows applications without installing Cygwin (a Unix-like environment and command line interface for Windows). Use an installer to install necessary packages. The installer, mingw-get-setup.exe, can be downloaded from Run the installer and select two packages: mingw32-base and mingw-gcc-g++. Then select the menu item, “Apply Changes” in the “Installation” menu.

Eclipse CDT

Find a Eclipse package with the latest CDT at And again download one according to your OS type. There are Eclipses with CDT for Windows 32-bit and 64-bit.

Project – Hello World ANSI C Project

Select “New – C Project.” Put a name in “Project name:” And select “MinGW GCC” as your “Toolchains:” The Toolchain is a set of programming tools. And we are using MinGW GCC as the toolchain.

Build the Project Manually at First

The newly generated project must be built manually at least once before you run the program. Go to and select the menu “Project – Build Project.”

That’s it.