Vision

This module provides an interface for grabbing an rtmp stream and using the images to do some processing in opencv.

How do I use this module?

1. Get frames from the raspberry pi camera

2. – here comes your own processing –

3. Publish the processed frames on an http server

4. You can view the http stream of your processed images in a web browser

Opencv Stream

Because of the rtmp stream needing to buffer some frames and waiting for P-Frames, importing this module might take up to 5 Seconds.

Examples

Using the Vision Module

import cv2
from compLib import Vision

while True:
    # get newest opencv frame from camera
    frame = Vision.Streaming.get_frame()

    # do some processing with the frame.....

    # publish frame to streaming server
    Vision.Streaming.publish_frame(frame)

Connect the raspberry pi to your internet and view the stream at: “http://your_raspi_ip:9898/”. This should display your raspberry pi camera. Note: the stream will lag a little bit BUT the processing of the image will be done in realtime.

The output on the website should show whatever your raspberry pi cam records:

Chessboard Detection

In this example we process the captured stream of images and want to detect chessboards. Run this example and point your raspberry pi camera to a chessboard and it should be detected.

For testing you can point it at this image:

import cv2
from compLib import Vision

while True:
    # get newest opencv frame from camera
    frame = Vision.Streaming.get_frame()

    criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 0.001)

    # convert image to grayscale image
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)

    # find the chessboard corners
    ret, corners = cv2.findChessboardCorners(gray, (6, 9), None)

    # draw detected chessboard position onto the image
    cv2.drawChessboardCorners(frame,  (6, 9), corners, ret)

    # publish frame to streaming server
    Vision.Streaming.publish_frame(frame)

Connect the raspberry pi to your internet and view the stream at: “http://your_raspi_ip:9898/”.

The output image should look like this:

Here is a screenshot of the stream website while viewing the chessboard in this documentation.