Willem Weertman

Heres the code to make these images for anyone who is interested. Sorry about the tabs getting removed, not sure whats up with that @experiment.com

import cv2 import os import numpy as np path_vid = r'C:\Users\wlwee\Documents\conferences_and_presentations\AchemS\2021_Submission\inverted_plume.avi' path_save_img = os.path.join(os.path.dirname(path_vid), os.path.basename(path_vid).split('.')[0] + '.png') cap = cv2.VideoCapture(path_vid) num_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT)) skip_start = int(0.05*num_frames) cap.set(cv2.CAP_PROP_POS_FRAMES, skip_start) img_iters = np.arange(0, num_frames - skip_start, 1) for i in range(0, max(img_iters)): success, img = cap.read() if success == False: print('error1 reading video') cap.release() break if i == 0: print(i) background = img elif i in img_iters: print(i) img = cv2.subtract(img, background) overlay = img background = cv2.addWeighted(background, 1, overlay, 0.8,0) cv2.imwrite(path_save_img, background)

import cv2 import os import numpy as np path_vid = r'C:\Users\wlwee\Documents\conferences_and_presentations\AchemS\2021_Submission\inverted_plume.avi' path_save_img = os.path.join(os.path.dirname(path_vid), os.path.basename(path_vid).split('.')[0] + '.png') cap = cv2.VideoCapture(path_vid) num_frames = int(cap.get(cv2.CAP_PROP_FRAME_COUNT)) skip_start = int(0.05*num_frames) cap.set(cv2.CAP_PROP_POS_FRAMES, skip_start) img_iters = np.arange(0, num_frames - skip_start, 1) for i in range(0, max(img_iters)): success, img = cap.read() if success == False: print('error1 reading video') cap.release() break if i == 0: print(i) background = img elif i in img_iters: print(i) img = cv2.subtract(img, background) overlay = img background = cv2.addWeighted(background, 1, overlay, 0.8,0) cv2.imwrite(path_save_img, background)

Outside of ethical concerns my biggest issue beyond with eating octopus is that generally I dislike eating nervous tissue. If you do ever get octopus cut the arm open and look at the size of the nerve cord, it makes up a sub stantial portion of the arms. If I could post a picture here I would, its a bit ridiculous, almost as if bone was replaced with nervous tissue. yuck!

Thank you Ben! It means a lot man.

Thank you David, I will try to keep the posts going

Thanks Anna!

If I am understanding this correctly. Something of known size so we can translate pixels into measurements of known length. As well as a way to count time. Time first. The camera counts time with an error of a few nano seconds, the video recordings are captured at 10 frames per second to save storage space, I have many weeks of footage. The time error is very low. Space is a bit trickier due to the spherical distortion of the lense. The python openCV library has an open source tool for calibrating cameras https://docs.opencv.org/3.4/d4/d94/tutorial_camera_calibration.html. By calibrating the camera we can flatten our coordinates using the calibration matrix. once our coordinates are flattened we can measure an object of known size on the bottom of the tank and then translate pixels to lengths. The camera is about as perpendicular to the bottom of the tank as I could get it. So the object measured at one point on the plane of the tanks bottom should reflect sizes elsewhere on the plain with reasonable accuracy. It is ~20 pixels per inch.

No sliced sushi :)

Yeah, would not want to be eaten by an octopus, would be one of the worse ways to go.

Thank you Peter! so am I! It is a fun project.

I'll post that