gistfile1.py

#!/usr/bin/python
# -*- coding: utf-8 -*-
from opencv.cv import *
from opencv.highgui import *
from threading import Thread
#import serial

class RobotVision:
    cvSize size
    cvImage hsv_frame, thresholded, thresholded2
    cvScalar hsv_min, hsv_max, hsv_min2, hsv_max2
    cvCapture capture;

    def InitBallTracking():
        globals size, hsv_frame, thresholded, thresholded2, hsv_min, hsv_max, hsv_min2, hsv_max2, capture
        print "Initializing ball Tracking"
        size = cvSize(640, 480)
        hsv_frame = cvCreateImage(size, IPL_DEPTH_8U, 3)
        thresholded = cvCreateImage(size, IPL_DEPTH_8U, 1)
        thresholded2 = cvCreateImage(size, IPL_DEPTH_8U, 1)

        hsv_min = cvScalar(0, 50, 170, 0)
        hsv_max = cvScalar(10, 180, 256, 0)
        hsv_min2 = cvScalar(170, 50, 170, 0)
        hsv_max2 = cvScalar(256, 180, 256, 0)

        storage = cvCreateMemStorage(0)

        # start capturing form webcam
        capture = cvCreateCameraCapture(-1)

        if not capture:
            print "Could not open webcam"
            sys.exit(1)

        #CV windows
        cvNamedWindow( "Camera", CV_WINDOW_AUTOSIZE );

    def TrackBall(i):
        t = Thread(target=TrackBallThread, args=(i,))
        t.start()

    def TrackBallThread(num_of_balls):
        globals size, hsv_frame, thresholded, thresholded2, hsv_min, hsv_max, hsv_min2, hsv_max2, capture
        while 1:
            # get a frame from the webcam
            frame = cvQueryFrame(capture)

            if frame is not None:

                # convert to HSV for color matching
                # as hue wraps around, we need to match it in 2 parts and OR together
                cvCvtColor(frame, hsv_frame, CV_BGR2HSV)
                cvInRangeS(hsv_frame, hsv_min, hsv_max, thresholded)
                cvInRangeS(hsv_frame, hsv_min2, hsv_max2, thresholded2)
                cvOr(thresholded, thresholded2, thresholded)

                # pre-smoothing improves Hough detector
                cvSmooth(thresholded, thresholded, CV_GAUSSIAN, 9, 9)
                circles = cvHoughCircles(thresholded, storage, CV_HOUGH_GRADIENT, 2, thresholded.height/4, 100, 40, 20, 200)

                # find largest circle
                maxRadius = 0
                x = 0
                y = 0
                found = False
                for i in range(circles.total):
                    circle = circles[i]
                if circle[2] > maxRadius:
                    found = True
                    maxRadius = circle[2]
                    x = circle[0]
                    y = circle[1]

                cvShowImage( "Camera", frame );

                if found:
                    print "ball detected at position:",x, ",", y, " with radius:", maxRadius

                if x > 420:
                    # need to pan right
                    servoPos += 5
                    servoPos = min(140, servoPos)
                    servo(2, servoPos)
                elif x < 220:
                    servoPos -= 5
                    servoPos = max(40, servoPos)
                    servo(2, servoPos)
                print "servo position:", servoPos
            else:
                print "no ball"