mekatronik

Lophtix notes about robotics and mechatronics

Links

• Programmera LEGO Mindstorms EV3 med Python via webbläsare (written in Swedish)

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Notes to be structured later...

Set up via sudo raspi-config

• Keyboard layout to match your physical keyboard
• enable ssh
• enable camera
• setup wifi
• extend filesystem (requires reboot after)

Check that camera works by running raspistill -o image.jpg if HDMI-display is connected it should show a 5 sec preview before taking and storing image.

$ sudo apt-get update
$ sudo apt-get upgrade

After checking python works

$ sudo apt-get install python-opencv
$ sudo apt-get install python-picamera python3-picamera

These command line calls should now pass without errors

$ python -c "import picamera"
$ python3 -c "import picamera"

Now time to combine with openCV: https://picamera.readthedocs.io/en/release-1.13/recipes2.html#capturing-to-an-opencv-object

Install PyTesseract (not finished) https://pypi.org/project/pytesseract/

pip install pillow
(pip install pytesseract)
(pip install opencv-python)

Install Tesseract

$ sudo apt install tesseract-ocr
(sudo apt-get install tesseract-ocr libtesseract-dev libleptonica-dev)

Version 4 of tesseract seems to require compilation for rasperry pi: https://raspberrypi.stackexchange.com/questions/89231/tesseract-ocr-4-x-beta-for-raspberry-pi

For python íntegration there is tesserocr https://github.com/sirfz/tesserocr but we did not get that to work now.

How you can get started with Tesseract
https://medium.freecodecamp.org/getting-started-with-tesseract-part-i-2a6a6b1cf75e

How to use image preprocessing to improve the accuracy of Tesseract
https://medium.freecodecamp.org/getting-started-with-tesseract-part-ii-f7f9a0899b3f

Detect whitlisted single character:
tesseract stdin stdout -c tessedit_char_whitelist=HSU -psm 10