Dynamic Time Warping with Python

Dynamic Time Warping (DTW) is a method to align two sequences such that they have minimum distance. For instance, two trajectories that are very similar but one of them performed in a longer time. Here is an example of my code with python. Here is my ROS package with C++ for DTW.

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Lucas–Kanade method optical flow with MATLAB

In this tutorial, I will show you how to estimate optical flow based on Lucas–Kanade method.  This project has the following scripts: Optical_flow_estimation, myFlow, myWarp, computeColor, flowToColor. The myFlow does the main job, it gets two images and a window length (patch length) and a threshold for accepting the optical flow.  In the following, you see the myFlow.  You can uncomment figure function calls

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Displaying Adjusted Frequencies of signal with Fast Fourier transform

In this tutorial, I will show you how to get Fast Fourier transform of a signal and then correctly display the signal. Link to the code in my Github repository.

    Getting Fourier transform of the signal:

 

 

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6DOF pose estimation with Aruco marker and ROS

ArUco is a simple yet great library for augmented reality applications. In this tutorial, I’m gonna show you how to track ArUco marker and estimate their 6DOF pose with ROS. For this tutorial, you only need a USB camera. You need to calibrate your camera before first. If you don’ know how to that just follow my other tutorial

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Send CMake param to catkin

It quite often happens that you need to send a CMake parameter to your catkin project, for instance, you need to build your code for debugging mode. The correct syntax is:

another example:

read more: http://wiki.ros.org/catkin/Tutorials/using_a_workspace  

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Calibrating a Monocular Camera with ROS

ROS use OpenCV for camera calibration but the format that it stores the data is different than OpenCV. Also, you need to know where to place the camera calibration files so ROS can find it and publish it. 1.First, you need to install usb cam package from ROS and uvcdynctrl to disable autofocus:

2.Open a terminal and run roscore:

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pkg-config and CMake

pkg-config and CMake If the library that you want to use is not coming with Find<package>. cmake you can use pkg-config files which are stored in “.pc”. The environmental variable PKG_CONFIG_PATH is the place that should point to the “.pc” files. Type in the shell:

To get the list of all available package configs, you can

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How to find CMake from arbitrary installed locations

In my other tutorial, I showed you how to install your code in an arbitrary location in Unix/ Linux systems. In this tutorial, I’m gonna show you how to find them after installation. Here I have two examples: OpenCV, PCL point cloud I can assume that you have compiled and installed them using the following command:

1)PCL

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