campos.py

This is an OpenCV application to measure the x,y position of an object, using 2 cameras at right angles. It imports cam_display.py. See this post for a code description, and usage information: some code changes may be required.

# OpenCV application to measure the x,y position of an object
# Copyright (c) Jeremy P Bentham 2019
# Please credit iosoft.blog if you use the information or software in it

VERSION = "Campos v0.07"

import sys, time, threading, cv2, numpy as np
import cam_display as camdisp

IMG_SIZE    = 1280,720          # 640,480 or 1280,720 or 1920,1080
DISP_SCALE  = 2                 # Scaling factor for display image
DISP_MSEC   = 50                # Delay between display cycles
CAP_API     = cv2.CAP_ANY       # API: CAP_ANY or CAP_DSHOW etc...
LOWER_DET   = np.array([240,  0,  0])       # Colour limits for detection
UPPER_DET   = np.array([255,200,200])
LABEL_FONT  = camdisp.QFont("Courier", 16)  # Font for image label

# Do colour detection on image
def colour_detect(img):
    mask = cv2.inRange(img, LOWER_DET, UPPER_DET)
    ctrs = cv2.findContours(mask, cv2.RETR_TREE,
                            cv2.CHAIN_APPROX_SIMPLE)[-2]
    if len(ctrs) > 0:
        (x,y),radius = cv2.minEnclosingCircle(ctrs[0])
        radius = int(radius)
        cv2.circle(img, (int(x),int(y)), radius, (255,255,0), 2)
        return x
    return 0

# Class to hold capture & display data for a camera
class CamCap(object):
    def __init__(self, cam_num, label, disp):
        self.cam_num, self.label, self.display = cam_num, label, disp
        self.imageq = camdisp.Queue.Queue()
        self.pos = 0
        self.cap = cv2.VideoCapture(self.cam_num-1 + CAP_API)
        self.cap.set(cv2.CAP_PROP_FRAME_WIDTH, IMG_SIZE[0])
        self.cap.set(cv2.CAP_PROP_FRAME_HEIGHT, IMG_SIZE[1])

# Main window
class MyWindow(camdisp.MyWindow):
    def __init__(self, parent=None):
        camdisp.MyWindow.__init__(self, parent)
        self.label.setFont(LABEL_FONT)
        self.camcaps = []
        self.disp2 = camdisp.ImageWidget(self)
        self.displays.addWidget(self.disp2)
        self.capturing = True

    # Start image capture & display
    def start(self):
        self.timer = camdisp.QTimer(self)   # Timer to trigger display
        self.timer.timeout.connect(self.show_images)
        self.timer.start(DISP_MSEC)         # Thread to grab images
        self.capture_thread = threading.Thread(target=self.grab_images)
        self.capture_thread.start()

    # Grab camera images (separate thread)
    def grab_images(self):
        while self.capturing:
            for cam in self.camcaps:
                if cam.cap.grab():
                    retval, image = cam.cap.retrieve(0)
                    if image is not None and cam.imageq.qsize()  0:
                    img = cv2.cvtColor(image, cv2.COLOR_BGR2RGB)
                    cam.pos = colour_detect(img)
                    self.display_image(img, cam.display, DISP_SCALE)
                    self.show_positions()

    # Show position values given by cameras
    def show_positions(self, s=""):
        for cam in self.camcaps:
            s += "%s=%-5.1f " % (cam.label, cam.pos)
        self.label.setText(s)

    # Window is closing: stop video capture
    def closeEvent(self, event):
        self.capturing = False
        self.capture_thread.join()

if __name__ == '__main__':
    app = camdisp.QApplication(sys.argv)
    win = MyWindow()
    win.camcaps.append(CamCap(2, 'x', win.disp))
    win.camcaps.append(CamCap(1, 'y', win.disp2))
    win.show()
    win.setWindowTitle(VERSION)
    win.start()
    sys.exit(app.exec_())

#EOF