THRESHOLD =(0, 30, -10, 2, -6, 6) # Grayscale threshold for dark things...
import sensor, image, time

sensor.reset()
#sensor.set_vflip(True)
#sensor.set_hmirror(True)
sensor.set_pixformat(sensor.RGB565)
sensor.set_framesize(sensor.QQVGA) # 80x60 (4,800 pixels) - O(N^2) max = 2,3040,000.
#sensor.set_windowing([0,20,80,40])
sensor.skip_frames(time = 2000)     # WARNING: If you use QQVGA it may take seconds
clock = time.clock()                # to process a frame sometimes.

while(True):
    clock.tick()
    img = sensor.snapshot().binary([THRESHOLD])
    line = img.get_regression([(100,100,0,0,0,0)], robust = True)
    if (line):
        
        rho_err = abs(line.rho())-img.width()/2
        if line.theta()>90:
            theta_err = line.theta()-180
        else:
            theta_err = line.theta()
        img.draw_line(line.line(), color=(255,0,0))
        print(rho_err,line.magnitude(),rho_err)

循迹程序，为什么画面里不显示教程里那个绿色的直线