CITRIS HD Time-lapse project

Introduction

The CITRIS time-lapse project is an attempt to capture the multi-year construction of the new CITRIS building at extremely high resolution. A 6-Megapixel Nikon D70 digital SLR camera is used to generate raw frames during construction hours at 18 seconds/frame. These are run through processing to generate the current web view (ala a slow-motion webcam) as well as several time-lapse movies. We will eventually post-process them into an archival HDTV 1080p movie summarizing the construction.

Current view from Soda Hall (wave your cursor across it to see the previous photo)

Time-lapse movies (The thumbnail is the shot at noon each day)

Early excavation

2004-11-15 to 2005-04-01
1:06, 320s/f, 34MB

Week	Monday	Tuesday	Wednesday	Thursday	Friday
2004–11–15  0:30, 160s/f, 11MB	2:09, 11s/f, 18MB	0:35, 40s/f, 6MB	0:30, 46s/f, 8MB	2:22, 10s/f, 26MB	0:27, 51s/f, 9MB
2004–11–22 0:18, 160s/f, 10MB	0:44, 31s/f, 14MB	0:42, 33s/f, 13MB	0:46, 30s/f, 13MB	No construction today	No construction today
2004–11–29 0:30, 160s/f, 16MB	0:34, 29s/f, 13MB	0:35, 40s/f, 8MB	1:05, 21s/f, 16MB	1:18, 18s/f, 26MB	1:17, 18s/f, 19MB
2004–12–06 0:24, 160s/f, 10MB	1:18, 18s/f, 20MB	1:20, 17s/f, 19MB	1:14, 19s/f, 11MB	1:15, 19s/f, 11MB	1:20, 17s/f, 18MB
2004–12–13 0:30, 160s/f, 12MB	1:20, 17s/f, 12MB	1:17, 18s/f, 14MB	1:16, 18s/f, 15MB	1:17, 18s/f, 19MB	1:16, 18s/f, 16MB

An IBM Thinkpad T23 PC laptop running Linux Fedora Core 3 was connected to a Nikon D70 digital SLR camera via Nikon's provided USB cable. We experimented with many cameras before settling on the D70. The camera was mounted on a sturdy tripod. Using the open-source gphoto2 program as the software foundation, we authored two simple scripts in tcsh, our time-lapse "driver" script that simply calls the take-photo script over and over and over again. The cycle time is approximately 18 seconds/frame, and in that time several things happen, as described below. Each image is captured as "JPEG Fine" quality (~3 MB/photo), which yields a little over 7.5 GB of data/day. The images are then sent for daily post-processing on an Apple Macintosh PowerBook G4 laptop. Here's the take-photo script:

1. The computer checks its watch
   1. If the time is outside of weekday daylight hours, it says "I don't work overtime!", sleeps for one minute then exits.
   2. If not, it continues...
2. It asks the camera to take a photo, download it, and delete its local copy (so as not to fill up the 256MB CompactFlash card)
3. It moves the current web thumbnail to the last thumbnail (for the web rollover)
4. It squashes the new image to be 1/4 of its original size and makes it the current web thumbnail
5. It copies the local 6 Megapixel image to the web as the current high-resolution image.

Post-processing the raw images into movies

There are ~2,500 images per day, each of which is scaled down, cropped and emblazened with a date and time icon signature based on when the photo was taken. This is done in Adobe After Effects, which saves the movie as archival 30 fps MPEG-4 Best-quality movies (~200 MB). The movies are then exported as Internet-streamable MPEG-4 Medium-quality movies using Apple's Quicktime player and uploaded.

• CITRIS : Center for Information Technology Research in the Interest of Society
• CITRIS Headquarters Construction site by Prof. Carlo Séquin
• Co-opticon : Prof. Ken Goldberg's CITRIS construction collaborative webcam
• Project Time-lapse : MIT's Stata Center's time-lapse project
• Playing with Time : A project with many time-lapse construction movies available