物体検出

object_detection.py

# -*- coding:utf-8 -*-

from __future__ import print_function, unicode_literals, division

import boto3
import cv2
import numpy as np
import urllib

## test data
# NUM_OF_HISTORY = 50
# BUCKET_NAME = 'mmitou'
# PREFIX = 'data3/'
# TOPIC_ARN = 'arn:aws:sns:ap-northeast-1:770170371212:test'
# RATIO_THRESHOLD = 10
# NUM_OF_WAIT = 3

TABLE_NAME = 'User'
ITEM_ID = 'test'

def get_latest_jpg_keys(bucket_name, prefix, num):
    s3 = boto3.resource('s3')
    bucket = s3.Bucket(bucket_name)
    # s3バケットの指定したprefixを持つ全てのファイルは、
    # 日付.jpgという名前である事を前提としている
    keys = sorted([objsummary.key for objsummary in bucket.objects.filter(Prefix=prefix) if objsummary.key.endswith('.jpg')])
    # 後ろからnum個だけ取得する
    latest_keys = keys[ (-num) if len(keys) > num else 0 : ]
    return latest_keys 

def get_file(bucket_name, key):
    s3 = boto3.resource('s3')
    obj = s3.Object(bucket_name, key)
    response = obj.get()
    string = response['Body'].read()
    return string

def string2img(string):
    mat = np.fromstring(string, np.uint8)
    img = cv2.imdecode(mat, cv2.IMREAD_COLOR)
    return img

def has_sent_notification():
    dynamodb = boto3.session.Session(region_name='ap-northeast-1').resource('dynamodb')
    table = dynamodb.Table(TABLE_NAME)
    response = table.get_item(Key = {'id':ITEM_ID})
    return response['Item']['has_sent']

def cancel_notification():
    dynamodb = boto3.session.Session(region_name='ap-northeast-1').resource('dynamodb')
    table = dynamodb.Table(TABLE_NAME)
    response = table.get_item(Key = {'id':ITEM_ID})
    response['Item']['has_sent'] = False
    table.put_item(Item = response['Item'])

def send_notification(bucket_name, key, topic_arn):
    sns = boto3.session.Session(region_name='ap-northeast-1').resource('sns')
    s3 = boto3.client('s3')
    topic = sns.Topic(topic_arn)
    url = s3.generate_presigned_url('get_object', Params = {'Bucket': bucket_name, 'Key': key})
    topic.publish(Subject='detected object', Message = url)

    dynamodb = boto3.session.Session(region_name='ap-northeast-1').resource('dynamodb')
    table = dynamodb.Table(TABLE_NAME)
    response = table.get_item(Key = {'id':ITEM_ID})
    response['Item']['has_sent'] = True
    table.put_item(Item = response['Item'])

def uploaded_image_key(event):
    bucket = event['Records'][0]['s3']['bucket']['name']
    key = urllib.unquote_plus(event['Records'][0]['s3']['object']['key']).decode('utf8')
    return key

def mask_ratio(mask):
    w, h = mask.shape
    p = cv2.countNonZero(mask) / (w * h)
    return int(p * 100)

def has_detected(mask_ratios, ratio_threshold, num_of_wait):
    return all([ratio > ratio_threshold for ratio in mask_ratios[- num_of_wait:]])

def has_detected_other_objects(mask_ratios, ratio_threshold, num_of_wait):
    return all([ratio > ratio_threshold and ratio <= mask_ratios[- num_of_wait] for ratio in mask_ratios[- 2 * num_of_wait:]]) 

def get_user_item():
    dynamodb = boto3.session.Session(region_name='ap-northeast-1').resource('dynamodb')
    table = dynamodb.Table(TABLE_NAME)
    response = table.get_item(Key = {'id':ITEM_ID})
    return response['Item']

def lambda_handler(event, context):
    item = get_user_item()
    topic_arn = item['topic_arn'].decode()
    num_of_wait = int(item['num_of_wait'])
    ratio_threshold = int(item['ratio_threshold'])
    num_of_history = int(item['num_of_history'])
    bucket_name = item['bucket_name'].decode()
    prefix = item['prefix'].decode()

    keys = get_latest_jpg_keys(bucket_name, prefix, num_of_history)

    if len(keys) < num_of_history:
        print('there are not required number of images.')
        return False

    imgs = [string2img(get_file(bucket_name, key)) for key in keys]
    substractor = cv2.createBackgroundSubtractorKNN()
    masks = [substractor.apply(img) for img in imgs]
    ratios = [mask_ratio(mask) for mask in masks[-2*num_of_wait:]]

    print(ratios)

    if has_sent_notification():
        if has_detected_other_objects(ratios, ratio_threshold, num_of_wait):
            print('detect other objects.')
            send_notification(bucket_name, keys[-1], topic_arn)
            return True

        if has_detected(ratios, ratio_threshold, num_of_wait):
            print('detected object had been notified.')
            return True

        print('detected object had gone.')
        cancel_notification()
        return False

    else:
        if has_detected(ratios, ratio_threshold, num_of_wait):
            print('detect new object')
            send_notification(bucket_name, keys[-1], topic_arn)
            return True
        else:
            print('there are no objects.')
            return False

take_pics.sh

#!/bin/sh

set -eu

if [ $# -ne 2 ]; then
  echo "Usage:"
  echo "${0} num_of_pics dest_dir"
  exit 1
fi

[ ! -d $2 ] && mkdir ${2}

for i in `seq 0 ${1}`; do
  path=${2}/`date +%Y-%m-%d-%H%M%S`.jpg
  echo ${i} ${path}
  fswebcam -r 640x480 --jpeg 85 -D 60 -S 30 --no-banner ${path}
  aws s3 cp ${path} s3://mmitou/${path} --profile s3user
done

User.csv