Python Hand tracking script crashing with a KeyError: 2 error

Question

I'm testing out a hand tracking volume control script. It runs but when I bring my hand into frame it instantly crashes. I get this error message: area = (bbox[2] - bbox[0]) * (bbox[3] - bbox[1]) // 100 KeyError: 2

If I comment out area = (bbox[2] - bbox[0]) * (bbox[3] - bbox[1]) // 100. It runs the scipt as normal but doesn't give me the volume controlling function.

Here is the complete code:

import cv2
import time
import numpy as np
import HandTrackingModule as htm
import math
from ctypes import cast, POINTER
from comtypes import CLSCTX_ALL
from pycaw.pycaw import AudioUtilities, IAudioEndpointVolume

################################
wCam, hCam = 640, 480
################################

cap = cv2.VideoCapture(0)
cap.set(3, wCam)
cap.set(4, hCam)
pTime = 0

detector = htm.HandDetector(detectionCon=0.7, maxHands=1)


devices = AudioUtilities.GetSpeakers()
interface = devices.Activate(
    IAudioEndpointVolume._iid_, CLSCTX_ALL, None)
volume = cast(interface, POINTER(IAudioEndpointVolume))
# volume.GetMute()
# volume.GetMasterVolumeLevel()
volRange = volume.GetVolumeRange()
minVol = volRange[0]
maxVol = volRange[1]
vol = 0
volBar = 400
volPer = 0
area = 0
colorVol = (255, 0, 0)

while True:
    success, img = cap.read()

    # Find hands

    img = detector.findHands(img)
    lmList, bbox = detector.findPosition(img, draw=True)
    if len(lmList) != 0:

        # Filter based on size

        area = (bbox[2] - bbox[0]) * (bbox[3] - bbox[1]) // 100
        #print(area)

        if 250 < area < 1000:
            #print("Yes")

            # Find Disteance  between index and thumb
            length, img, lineInfo = detector.findDistance(4, 8, img)
            #print(length)

            # Convert volume
            volBar = np.interp(length, [50, 200], [400, 150])
            volPer = np.interp(length, [50, 200], [0, 100])

            # Reduce reselution to make it smoother
            smoothness = 10
            volPer = smoothness * round(volPer / smoothness)

            # Check fingers for up
            fingers = detector.fingersUp()
            print(fingers)

            # if pinky is down set volume
            if not fingers[4]:
                volume.SetMasterVolumeLevelScalar(volPer / 100, None)
                cv2.circle(img, (lineInfo[4], lineInfo[5]), 15, (0, 225, 0), cv2.FILLED)
                colorVol = (225, 0 ,0)
            else:
                colorVol = (0, 255, 0)

    # drawings
    cv2.rectangle(img, (50, 150), (85, 400), (225, 0, 0), 3)
    cv2.rectangle(img, (50, int(volBar)), (85, 400), (225, 0, 0), cv2.FILLED)
    cv2.putText(img, f' {int(volPer)} %', (40, 450), cv2.FONT_HERSHEY_COMPLEX, 1, (225, 0, 0), 3)

    cVol = int(volume.GetMasterVolumeLevelScalar() * 100)
    cv2.putText(img, f'Vol Set: {int(cVol)}', (400, 50), cv2.FONT_HERSHEY_COMPLEX, 1, colorVol, 3)

    # Frame rate
    cTime = time.time()
    fps = 1/(cTime - pTime)
    pTime = cTime

    cv2.putText(img, f'FPS: {int(fps)}', (40, 50), cv2.FONT_HERSHEY_COMPLEX, 1, (255, 0, 0), 3)


    cv2.imshow("image", img)

    cv2.waitKey(1)

I've looked everywhere but came up empty handed. If you know how to fix this please let me know.

Answer 1

I assume HandTrackingModule is this, and it's been updated since you downloaded it since it no longer has a HandDetector class. It does however have a FindHands class with a getPosition() method. I assume this is equivalent to your detector.findPosition().

The method returns a list of hands, so when you index into it you're selecting which hand you want and indexing with 2 will fail unless there are at least 3 hands. If it has multiple hands then the list will be length > 1.

Rename what you've currently called bbox to bboxes, since it's plural, then do:

    areas = [
        (bbox[2] - bbox[0]) * (bbox[3] - bbox[1]) // 100
        for bbox in bboxes
    ]
    for area in areas:
        print(area)