Larry Lindsey

Yacht TV

Automatically detect boats and save video clips as they pass. Based on a Google AIY Vision Kit.

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Yacht TV

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Hardware components

AIY Vision
Google AIY Vision


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Video Detection Capture

A Python script for use on the AIY Vision Kit. Insert it into the vision examples directory, then run from the command line. See the --help option for more info.
#!/usr/bin/env python3
# Copyright 2017 Google Inc.
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# See the License for the specific language governing permissions and
# limitations under the License.
"""Video capture by class detection demo.
This script continuously monitors the Raspberry Camera and tries to detect
instances of a set of specified classes/categories. When on is detected a
short video file is written capturing briefly before and after the capture.
Example usage:
python -c boat_classes.txt --out_dir my_captures/
The file boat_classes.txt contains the desired set of classes to look for.
It is simply a text file containing one class per line:
container ship/containership/container vessel
paddle/boat paddle
pirate/pirate ship
paddlewheel/paddle wheel
A full list of possible categories can be obtained here:
import argparse
import io
import numpy as np
import os
import picamera
import pickle
import sys
import time
from PIL import Image
from import ImageInference
from import image_classification
def crop_parameters(im, range_x=[0, 1], range_y=[0, 1]):
  """Yields crop parameters for the given x- and y-ranges"""
  size = np.array(im.size).astype(
  crop_size = (size / 4).astype(
  step = (crop_size / 2).astype(
  x_start = int(range_x[0] * size[0])
  x_end = int(range_x[1] * size[0] - crop_size[0]) + 1
  y_start = int(range_y[0] * size[1])
  y_end = int(range_y[1] * size[1] - crop_size[1]) + 1
  for y in range(y_start, y_end, step[1]):
    for x in range(x_start, x_end, step[0]):
      yield (x, y, x + step[0] * 2, y + step[1] * 2)
debug_idx = 0
def debug_output(image, debug_data, out_dir, filename=None):
  """Outputs debug output if --debug is specified."""
  global debug_idx
  if debug_idx == 0:
    for filepath in [f for f in os.listdir(out_dir) if f.startswith('image_')]:
        path_idx = int(filepath[6:12]) + 1
        debug_idx = max(debug_idx, int(filepath[6:12]) + 1)
  print('debug_idx:', debug_idx)
  if filename == None:
    output_path = os.path.join(out_dir, 'image_%06d.jpg' % (debug_idx))
    debug_idx += 1
    output_path = os.path.join(out_dir, filename)
  with open(output_path + '_classes.txt', 'w') as f:
    for debug_tuple in debug_data:
      f.write('%s + %s Result %d: %s (prob=%f)\n' % debug_tuple)
  with open(output_path + '_classes.pkl', 'wb') as f:
    pickle.dump(debug_data, f, protocol=0)
def detect_object(inference, camera, classes, threshold, out_dir, range_x=[0,1], range_y=[0,1]):
  """Detects objects belonging to given classes in camera stream."""
  stream = io.BytesIO()
  camera.capture(stream, format='jpeg')
  image =
  # Every so often, we get an image with a decimated green channel
  # Skip these.
  rgb_histogram = np.array(image.histogram()).reshape((3, 256))
  green_peak = np.argmax(rgb_histogram[1, :])
  if green_peak < 3:
    return False, None, None
  debug_data = []
  detection = False
  max_accumulator = 0.
  print ('Inferring...')
  for p in crop_parameters(image, range_x, range_y):
    im_crop = image.crop(p)
    accumulator = 0.
    infer_classes = image_classification.get_classes(, max_num_objects=5, object_prob_threshold=0.05)
    corner = [p[0], p[1]]
    print (corner)
    for idx, (label, score) in enumerate(infer_classes):
      debug_data.append((corner, im_crop.size, idx, label, score))
      if label in classes:
        accumulator += score
    if accumulator > max_accumulator:
      max_accumulator = accumulator
    if accumulator >= threshold:
      detection = True
  if out_dir != '':
    debug_output(image, debug_data, out_dir)
  print ('Accumulator: %f' % (max_accumulator))
  print ('Detection!' if detection else 'Non Detection')
  return detection, image, debug_data
def main():
  parser = argparse.ArgumentParser()
  parser.add_argument('--classfile', '-c', dest='classfile', required=True)
  parser.add_argument('--threshold', '-t', dest='threshold', required=False, type=float, default=0.5)
  parser.add_argument('--out_dir', '-o', dest='out_dir', required=False, type=str, default='./')
  parser.add_argument('--capture_delay', dest='capture_delay', required=False, type=float, default=5.0)
  parser.add_argument('--capture_length', dest='capture_length', required=False, type=int, default=20)
  parser.add_argument('--debug', '-d', dest='debug', required=False, action='store_true')
  ## Crop box in fraction of the image width. By default full camera image is processed.
  parser.add_argument('--cropbox_left', dest='cropbox_left', required=False, type=float, default=0.0)
  parser.add_argument('--cropbox_right', dest='cropbox_right', required=False, type=float, default=1.0)
  parser.add_argument('--cropbox_top', dest='cropbox_top', required=False, type=float, default=0.0)
  parser.add_argument('--cropbox_bottom', dest='cropbox_bottom', required=False, type=float, default=1.0)
  args = parser.parse_args()
  # There are two models available for image classification task:
  # 1) MobileNet based (image_classification.MOBILENET), which has 59.9% top-1
  # accuracy on ImageNet;
  # 2) SqueezeNet based (image_classification.SQUEEZENET), which has 45.3% top-1
  # accuracy on ImageNet;
  model_type = image_classification.MOBILENET
  # Read the class list from a text file
  with open(args.classfile) as f:
    classes = [line.strip() for line in f]
  print('Starting camera detection, using the following classes:')
  for label in classes: print ('  ', label)
  print('Threshold:', args.threshold)
  print('Debug mode:', args.debug)
  print('Capture Delay:', args.capture_delay)
  debug_out = args.out_dir if args.debug else ''
  with ImageInference(image_classification.model(model_type)) as inference:
    with picamera.PiCamera(resolution=(1920, 1080)) as camera:
      stream = picamera.PiCameraCircularIO(camera, seconds=args.capture_length)
      camera.start_recording(stream, format='h264')
      while True:
        detection, image, inference_data = detect_object(
          inference, camera, classes, args.threshold, debug_out,
          [args.cropbox_left, args.cropbox_right],
          [args.cropbox_top, args.cropbox_bottom])
        if detection:
          detect_time = int(time.time())
          video_file = 'capture_%d.mpeg' % (detect_time)
          image_file = 'capture_%d.jpg' % (detect_time)
          stream.copy_to(os.path.join(args.out_dir, video_file))
          debug_output(image, inference_data, args.out_dir, image_file)
          print('Wrote video file to', os.path.join(args.out_dir, video_file))
          camera.wait_recording(max(args.capture_length - args.capture_delay, 0))
if __name__ == '__main__':


Larry Lindsey

Larry Lindsey

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