Calcolo distanza tra 2 Aruco tags con OpenCV

Invece di calcolare la distanza tra la camera ed un tag in questo caso volevo vedere se riuscivo a calcolare la distanza tra due tag 

Raffronto la distanza reale tra due tag e la distanza calcolata da OpenCV. L'errore e' dell'ordine del cm

Nel video effettuato con un drone si vede come la distanza tra i due tag venga correttamente letta come costante nonostante il punto di riprese si muova

'''

Sample Command:-

python detect_aruco_video.py --type DICT_5X5_100 --camera True

python detect_aruco_video.py --type DICT_5X5_100 --camera False --video test_video.mp4 -a 25 -k ./calibration_matrix.npy -d ./distortion_coefficients.npy

'''

from turtle import delay

import numpy as np

from utils import ARUCO_DICT, aruco_display

import argparse

import time

import cv2

import sys

import math

import time

def isRotationMatrix(R):

Rt = np.transpose(R)

shouldBeIdentity = np.dot(Rt, R)

I = np.identity(3, dtype=R.dtype)

n = np.linalg.norm(I - shouldBeIdentity)

return n < 1e-6

def rotationMatrixToEulerAngles(R):

assert (isRotationMatrix(R))

sy = math.sqrt(R[0, 0] * R[0, 0] + R[1, 0] * R[1, 0])

singular = sy < 1e-6

if not singular:

x = math.atan2(R[2, 1], R[2, 2])

y = math.atan2(-R[2, 0], sy)

z = math.atan2(R[1, 0], R[0, 0])

else:

x = math.atan2(-R[1, 2], R[1, 1])

y = math.atan2(-R[2, 0], sy)

z = 0

return np.array([x, y, z])

R_flip = np.zeros((3,3), dtype=np.float32)

R_flip[0,0] = 1.0

R_flip[1,1] =-1.0

R_flip[2,2] =-1.0

ap = argparse.ArgumentParser()

ap.add_argument("-i", "--camera", help="Set to True if using webcam")

ap.add_argument("-v", "--video", help="Path to the video file")

ap.add_argument("-t", "--type", type=str, default="DICT_ARUCO_ORIGINAL", help="Type of ArUCo tag to detect")

ap.add_argument("-k", "--K_Matrix", required=True, help="Path to calibration matrix (numpy file)")

ap.add_argument("-d", "--D_Coeff", required=True, help="Path to distortion coefficients (numpy file)")

ap.add_argument("-a", "--aruco_dim", required=True, help="ArUco tag dimension")

args = vars(ap.parse_args())

if args["camera"].lower() == "true":

video = cv2.VideoCapture(0)

time.sleep(2.0)

else:

if args["video"] is None:

print("[Error] Video file location is not provided")

sys.exit(1)

video = cv2.VideoCapture(args["video"])

if ARUCO_DICT.get(args["type"], None) is None:

print(f"ArUCo tag type '{args['type']}' is not supported")

sys.exit(0)

arucoDict = cv2.aruco.Dictionary_get(ARUCO_DICT[args["type"]])

calibration_matrix_path = args["K_Matrix"]

distortion_coefficients_path = args["D_Coeff"]

k = np.load(calibration_matrix_path)

d = np.load(distortion_coefficients_path)

arucoParams = cv2.aruco.DetectorParameters_create()

while True:

ret, frame = video.read()

time.sleep(0.05)

if ret is False:

break

h, w, _ = frame.shape

width=1000

height = int(width*(h/w))

frame = cv2.resize(frame, (width, height), interpolation=cv2.INTER_CUBIC)

corners, ids, rejected = cv2.aruco.detectMarkers(frame, arucoDict, parameters=arucoParams)

detected_markers = aruco_display(corners, ids, rejected, frame)

if len(corners) > 0:

#print(corners) #posizione degli angoli del marker

#print(len(ids))

if (len(ids) == 2):

for i in range(0, len(ids)):

rvec, tvec, markerPoints = cv2.aruco.estimatePoseSingleMarkers(corners[i], float(args["aruco_dim"]), k,d)

if (i == 0):

tvec0 = tvec

print(tvec0)

else:

tvec1 = tvec

print(tvec1)

distanza= "Dist=%4.0f"%(np.linalg.norm(tvec1-tvec0))

cv2.putText(frame, distanza,(50, 100),cv2.FONT_HERSHEY_SIMPLEX, 1,(0, 0, 255), 2, cv2.LINE_4)

cv2.imshow("Image", detected_markers)

key = cv2.waitKey(1) & 0xFF

if key == ord("q"):

break

cv2.destroyAllWindows()

video.release()