Project: Turtle-Sketch

Overview

• In this project, the image on the left is taken as input and the image on the right is obtained as output by using turtlesim

• The image on the left can be selected using it's path as well as can be directly taken from the camera

• The below videos show the project in action

  Click on the below animations for full video

Using an image

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Using webcam

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Concepts Used

Following are the concepts used for this project:

• Dynamic reconfigure
  • To import the image using path
  • To import the image using camera
  • To set thresholds for Canny edge detection
• ROS parameters
  • To set the values of threshold parameters
  • To fetch the values of threshold parameters
• ROS services
  • To spawn the turtles
  • To teleport the turtle
  • To set the status of a pen as - ON/OFF
  • To remove the turtles after sketch is completed
• OpenCV
  • To import image
  • To find the edges using Canny edge detection
  • To find the contours
• Multi-processing
  • To spawn an army of turtles to draw the sketch

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Directory Structure

• The directory contains 3 packages:

  • sketch
  • dynamic reconfigure
  • image_thresholding

• Sketch directory structure

  ├── CMakeLists.txt
  ├── docs                                 # Supported files for documentation
  │   ├── Contours.png
  │   ├── done.png
  │   ├── dynamic reconfigure.png
  │   ├── edges.png
  │   ├── Output.png
  │   ├── rosgraph.png
  │   ├── test.png
  │   └── turtles.png
  ├── include
  │   └── sketch
  ├── launch                                # Launch Files
  │   └── sketcher.launch
  ├── package.xml
  ├── README.md
  ├── nodes                                 # ROS Nodes
  │   ├── ironman.jpeg
  │   ├── sketcher.py
  │   └── Turtle.py
  └── TODO.md                               # TO DO for next version
  

• Image_thresholding directory structure

  .
  ├── cfg                                    # Configuration file for GUI
  │   ├── import.cfg                         # GUI params related to image import
  │   └── thresholds.cfg                     # GUI params related to image thresholding
  ├── CMakeLists.txt
  ├── include
  │   └── dynamic_parameters
  ├── launch                                 # Launch files 
  │   └── canny_thresholding.launch            # Launch - GUI for Canny edge detection
  ├── nodes                                  # ROS Nodes
  │   ├── get_values.py
  │   ├── import_server.py                   # Import Image import parameters in python node
  │   └── server.py                          # Import thresholding parameters in python node
  └── package.xml
  

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Coding Style Guide - PEP8

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Dependencies

• dynamic reconfigure package
• OpenCV

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Setup and Run

To run the project on your local system, follow the procedure:

• Download the packages - sketch, image_thresholding, and dynamic-reconfigure-noetic-devel

• Copy these packages to your ROS workspace i.e. ~/ROS_ws/src/

• Build the workspace

  • $ cd ~/ROS_ws/
  • $ catkin_make

• Open new terminal and source the ROS workspace - source ~/ROS_ws/devel/setup.bash

• Run the command - $ roslaunch sketch sketcher.launch

• This command will open turtlesim and GUI for this project

  

  

• You can select image Address (0) or Camera (1) option for CaptureType

• If you select Address (0), insert the path of the image on you system in the img_path section

• Then click on the checkbox in front of Capture

• If you select Camera (0), camera window will pop-up and you can click on the checkbox in front of Capture once you get the desired frame

• This will open up a window with edges in the selected frame

  

• Now, use the GUI to set minimum and maximum threshold values to get the desired contours

• Click on the checkbox in front of Start to spawn an army of turtles which will sketch these contours for you

  

• After the sketch is completed, the turtles will disappear

  

Note:

• If you want to change the approach to sequential from parallel, follow the steps:
  1. Open launch file in this directory ~/ROS_ws/sketch/launch/
  2. The arg tag for the sketcher node has a value of 1
  3. Change this value to 0
• Here, 0 = sequential execution and 1 = parallel execution

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