Archive for the ‘Devices/Gadget’ Category

Evaluation of Logitech C910 webcam for Computer Vision use

Friday, April 1st, 2011

I’ve recently been using a pair of PlayStation 3 Eye’s for reading structured light patterns projected onto objects. These particular cameras have had a lot of attention from hackers due to their value/performance.

The PS3Eye is a camera built for machine vision, and can provide ‘lossless’ 640×480 RGB frames at 60 frames per second with low latency, and is therefore particularly relevant for realtime tracking applications (e.g. multi-touch, 3-phase scanning). For OSX there is Maccam driver, and for Windows there is the fully featured CLEye driver from Alexp which supports programatic control of multiple cameras with full support for all camera features and also gives camera identity (through a GUID), and is free for 1 or 2 cameras per system.

But for a recent project, it became apparent that I needed resolution rather than framerate. My first instinct was to move to DSLR’s, and I began working with developing a libgphoto2 extension for openFrameworks called ofxDSLR. This route had the following issues:

  • Relatively expensive (compact cameras do not support remote capture, meaning I would have to use DSLR’s, with the cheapest compatible options at around £350 with lens – Canon 1000D+18-55mm lens)
  • Requires external power supply / recharging
  • Heavier than machine vision cameras
  • Flaky libraries (libghoto2 isn’t really built with CV in mind, and I found it was taking a lot of time to get results. And lack of solutions for Windows)
  • Slow capture (several seconds between send capture command and receive full result)

A DSLR offers:

  • Fantastic resolution
  • Great optics
  • Programmatic control of ISO, Focus, Shutter, Aperture
  • More than 8bits per colour

Due to the above issues, I decided to explore other options. This led me to the Logitech C910 which supports continuous capture at roughly 20x as many pixels as the PS3eye but at 1/120th of the frame rate.

Without further ado, here’s the video documentation (I recommend you chose either 720p or 1080p for viewing).

YouTube Preview Image

Notes:

Capture

Driver

  • UVC device (capture supported on all major desktop OS’s)
  • As of 1st April 2011, there is no way to programatically control the C910 from OSX, but this is likely to come soon (see here and here)
  • Programatic control from Windows through DirectShow. I recommend Theo Watson’s videoInput class for c++, which is included with openFrameworks or available as standalone.
  • I haven’t yet seen a way to uniquely identify a camera (Each PS3Eye can report its GUID identity, which is useful for recognising individual cameras in a multicam system)

Compression options

  • YUY2 (YUV 4:2:2) = lossless luminance, half resolution colour
  • MJPG = lossy, but higher frame rates supported than YUY2, since lower bandwidth required.

Programatic control of

  • Motorised focus
  • Shutter speed (aka exposure)
  • Gain (aka brightness)
  • ‘Hacky’ Region of Interest {ROI} (through digital Zoom, Pan, Tilt)

Focus

  • ~12 discrete focus steps (i.e. focus control is NOT continuous)
  • Furthest focus point is ~70cm, beyond this is classed as ‘infinity’
  • With sharpening turned off (i.e. getting more of the ‘raw’ image), we see a general lack of focus on surfaces other than at discrete steps
  • Closest macro focus at 3.5cm

Focus table [control value 0-255 / distance (cm)]

  • 255 / 3.5
  • 238 / 3.8
  • 221 / 4
  • 204 / 4.3
  • 187 / 5.3
  • 170 / 6.4
  • 153 / 8
  • 136 / 10.5
  • 119 / 15
  • 102 / 25
  • 85 / 40
  • 68 / 51

See also

BirdBox

Thursday, January 21st, 2010

Aile forwarded this to let me help spreading Durrell’s lovely new product over the world. :)
Durrell (Visiting faculty of CIID, Founder of Luckybite) and Tom have a new product which mixes the iPhone with physical things! (which is also same idea of mine currently!)
It’s a physical BirdBox that turns your iPhone into a nesting box cuckoo alarm clock. The app is free and has just gone live on the app store at http://itunes.com/apps/birdbox and you can buy your box at www.luckybits.com

Aile에게서 포워딩 받은 새로운 뉴스. :)
우리의 외부 교수이자 럭키바이트의 대표, 디자이너이신 Durrell Bishop이 아이폰과 피지컬 오브젝트가 상호작용하는 신제품을 내놓았다는 뉴스이다.
Tangible User Interface과목에서 독특한 크리틱으로 우리를 조마조마하게 했던 분.. :)
무엇보다도 현재 내가 가지고 있는 아이디어, 아이폰+피지컬 오브젝트, 에 딱 들어맞는 제품이라 더 관심이 간다.

light touch

Thursday, January 14th, 2010

light blue optics is showcasing their interactive tabletop projector the light touch at CES 2010.
the light touch allows users to turn any flat surface, vertical or horizontal, into an interactive touchscreen.
the device is pocket size and hooks up to a variety of devices such as a mobile phone to provide a large multi-touch display. the projector uses holographic laser projection which create bright and high quality images on any surface. infrared sensors detect motion so users can control their device uses gestures on the projected surface. the company isn’t set to release the product anytime soon, but they do think it would be useful for individual users on the go or in the home, workplace or even commercial environments.

http://lightblueoptics.com

ion audio iphone accessories

Thursday, January 14th, 2010

ion audio showcased a series of iphone accessories that transform the small mobile device into a laptop, piano and dj set. these new peripherals complement the company’s existing line of computer and music devices. the idiscover keyboard is a small 25 key piano with a docking station for the iphone or ipod touch. once the mobile device is docked, the keyboard can be used to create music through various applications. the itype is a similar device that uses a qwerty keyboard to enhance a docked iphone or ipod touch, allowing users to have a full size keyboard on their mobile device. the third accessory is the dj dock which turns the iphone into a dj mixing studio, enabling users to scratch and add effects to their favourite songs.

http://www.ionaudio.com

Mimi says ;
“I’ve been thinking of developing iPhone application which works with physical objects or devices, since I saw the movie “iphone + book”, since I realised that my son is really into using iPhone and iTouch! iPhone just interacts with my son in a very natural, intuitive and spontaneous way. Can we make iPhone application for little children??”

Soft toy Wii game

Friday, January 1st, 2010
YouTube Preview Image

PhoneBook

Saturday, November 28th, 2009

New concept of Mobile Art Lab