Multi-Day Time Lapse for (White Fluffy Clouds)

Thursday, October 8th, 2015


Not long ago, I stumbled upon Ken Murphy’s amazing History of the Sky project.  The concept is simple; take a picture of the from sunrise to sunset every 10 seconds every day for a year.  He then made a mosaic of the images, and ran it as a slide show all at once.  You know what, I think its easier if I just show you what he did:

A History of the Sky from Ken Murphy on Vimeo.

Around the time I found this, I started diving in to the Raspberry Pi, and I thought that this little computer could probably reproduce Ken’s amazing project.  I thought I could update it with the Chicago Skyline.

After a series of false starts, I finally got a Raspberry Pi and camera sealed inside a sandwich container (my version of a weather-proof box).  It is currently sitting on the roof of the McGowan Science building at DePaul University.  It wakes up at 4:30AM every day, and takes a picture every 10 seconds until 8:30AM.  That is 360 pictures per hour or 1440 per day.  Another program compresses them into a movie, which gets uploaded into my DropBox account.  My project started on October 1st, 2015, so I have captured a week of Chicago sunrises.  Here is the first one:

Another Raspberry Pi downloads the movies, and breaks them into a series of stills.  When I have enough, they will be assembled into a mosaic image, and turned back into a movie.  With luck, I will have 365 movies to work with.

This Python Program is what I use to take the pictures.

import time
import picamera


file = "/home/pi/camera/frame_%04d.jpg"
#file = str("/home/pi/camera/" + time.strftime("%Y%m%d") + "_%04d.jpg")

def capture_frame(frame):
with picamera.PiCamera() as cam:
cam.capture(file % frame)

# Capture the images
for frame in range(FRAMES):
# Note the time before the capture
start = time.time()
# Wait for the next capture. Note that we take into
# account the length of time it took to capture the
# image when calculating the delay
int(60 * 60 / FRAMES_PER_HOUR) - (time.time() - start)

This code was used to turn it into a movie. It is a bash script


DATE=$(date +"%Y%m%d")

avconv -r 10 -i /home/pi/camera/frame_%04d.jpg -r 10 -vcodec libx264 -crf 20 -g 15 /home/pi/camera/$DATE.mp4

Finally, this Python Program uploaded it to DropBox.

import time
from subprocess import call

date = time.strftime("%Y%m%d")
path = "/home/pi/camera/"+date+".mp4"
destination = date+".mp4"

photofile = "/home/pi/Dropbox-Uploader/ upload "+path+" "+destination

call ([photofile], shell=True)

It isn't very difficult, and this is the best way to really see the days getting longer and shorter, and connecting that to the Earth's tilt as it goes around the sun.

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