20

I would like to know how does Kinect work and how it is different from Nintendo Wii motion system?

badp
  • 56,684
  • 51
  • 238
  • 442
  • It's a lot like the PlayStation EyeToy and before that, webcam software. In 1998 I bought a (not-too-fancy) Logitech webcam that came with some games which would allow you to for example bounce a virtual ball with your hands. It would capture your image with the camera, detect your form, then use that to create models for collision detection, then finally display your picture on the screen with a super-imposed ball or whatever which would react to your movements. It was really cool and it only took a dozen years for similar tech to go mainstream. – Synetech Nov 22 '10 at 20:26
  • 4
    @Synetech: Actually, it's completely different from those things – BlueRaja - Danny Pflughoeft Dec 07 '10 at 01:34
  • @BlueRaja, how so? The answer below shows it does the same thing, just using more advanced detection methods. – Synetech Dec 10 '10 at 01:24
  • 1
    @Synetech: Read the first paragraph of that answer. Kinect's technology is different in almost every way from a webcam - those webcams have no sense of depth, so they can't really detect "you," only your movement, which is why they worked so poorly. There is simply no way to make something like Kinect work with just a webcam, no matter how high its resolution. – BlueRaja - Danny Pflughoeft Dec 10 '10 at 03:17
  • @BlueRaja, yes, the depth is the enhanced part. They still basically detect the user in some manner and use that as input to the game logic. They are all just computer-vision (ie optical recognition) finally adapted to gaming/entertainment. – Synetech Dec 10 '10 at 03:43
  • By the way, there are a couple of articles on Move vs. Kinect vs. Wii as well as programming augmented-reality in this month's (Dec 2010) issue of Game Developer Magazine.
    The article "Electric Eye - Pattern Recognition in Augmented Reality" on page 22 describes exactly what I mentioned in the above comment. ;)     – Synetech Dec 13 '10 at 03:17

4 Answers4

25

Kinect is based on the hardware, and possibly software, of PrimeSense. They use a flashing IR light-source and a filtered camera to measure time-in-flight and compute a depth map from that. Presumably, objects that are near-field and/or moving are detected as people, while static and far-away stuff is treated as background.

In contrast, the Wiimote has an IR camera and accelerometers built into it. The sensor bar that you put on/near your TV contains a pair of IR LEDs. The hardware in the Wiimote tracks those LEDs and determines which way it's pointing based on their position.

alt text

alt text

Ivo Flipse
  • 7,284
  • 23
  • 67
  • 102
  • 6
    Did anyone see what images did to this answer? :) – Ivo Flipse Sep 17 '10 at 07:22
  • Please note that although this is the highest voted answer, it is not actually correct. See @JohnRobertson's answer for the actual way that the kinect works (including a live video with the kinect) – LoveAndCoding Feb 22 '12 at 03:01
16

Kinect is very different from the Nintendo Wii.

The Nintendo Wii requires you to be holding WiiMotes and only cares where the WiiMotes are and what they are doing.

Instead, Kinect tracks your body in 3 dimensions and tries to do 1:1 replication of your movements. So if you jump, Kinect will see it and make your character jump on the screen.

Kinect also has built in headset-free chat, so you can talk to the game/other players freely.

th3dude
  • 434
  • 5
  • 8
6

Kinect does not use time of flight. It uses an IR projector and an IR camera. You can even see the results of the IR projector using a camcorder with night vision. The most thorough description I have seen is here which includes footage.

John Robertson
  • 571
  • 1
  • 6
  • 8
4

Given that the Kinect is capturing a scene and then doing image processing on the result there is the possibility that it will make more mistakes when calculating your position and movements than the Wii which relies on the remote. While I'm sure that the developers at Microsoft have done all they can, it would pay you to make sure that you follow the instructions very carefully when siting the Kinect bar etc.

The Wii remote has an infrared camera which needs to see the 2 IR LEDs on the sensor bar to work out it's position and orientation. It sends this together with the accelerometer data to the console. The remotes have a definite range - beyond which they either can't detect the sensor bar or the apparent distance between the lights is too small for it to calculate it's position.

ChrisF
  • 9,404
  • 6
  • 55
  • 88
  • 3
    You're correct that the Kinect algorithms might not be fail-proof (especially during the dancing game!), but might I remind people that I can play Wii tennis on the couch with just some wrist movements? – Ivo Flipse Jul 21 '10 at 21:19
  • 4
    @Ivo Yeah, but that would make you a tool. – Grace Note Sep 16 '10 at 13:02