Microsoft Kinect: The AnandTech Review
by Brian Klug on December 9, 2010 3:20 PM ESTKinect - Environmental Constraints
There are a lot of environmental constrains that the Kinect imposes, but the system actually works extremely well. Inside the manual and throughout the literature distributed with Kinect are notices about reducing ambient sunlight in the room you’re using the Kinect. At the same time, you need ambient light for the RGB color camera to work - this seems somewhat confusing until you consider that sunlight also contains spectral components at the same wavelength the Kinect operates at. Lots of ambient sunlight thus decreases the visibility of those spots on the room and players, and could conceivably make depth detection much worse. That sort of reminds me how the Wii sensor bar could be emulated with candles some distance apart atop the television, or how playing with the Wii next to a fireplace could easily make the system glitch out.
In practice, I never once noticed problems with depth detection on Kinect that I’d blame on ambient noise from stray light sources - even in a room with, yes, a huge fireplace (hey, it’s a reasonable test). The more important consideration actually turns out to be the relatively poor sensitivity of the RGB camera, which requires lots of room lighting to get decent framerate or augment facial detection.
The more important consideration for playing space is play space size - you need a big room to use Kinect. On the back of the Kinect packaging, Microsoft notes that a distance of 6’ from TV to players is requisite at minimum. After a lot of testing, I’d say 6’ is optimistic, even for one person. In actuality I’d say 9’-12’ is closer to what is optimal, especially if you want to play with a second person, and later inside games you’ll be told as much.
Sensor position itself makes a lot of difference here - Kinect can go either on top or below the TV, and Microsoft recommends anywhere 2’ - 6’ off the ground. Ultimately, the bar is that Kinect needs to be able to see your entire person - feet, head, and some distance around you to move, jump, and flail your arms around inside. If you place the Kinect on an entertainment center table below the TV, the hazard is that the depth of the table will block part of the depth image at the bottom. I had much more success with placing the Kinect atop TVs, especially when you encounter LCDs and pasmas of the wall-mounted sort.
The first area I tested was my living room, which is reasonably large (or so I used to think), and I played with about 7 feet away from the sensor. I moved a coffee table, unfortunately moving my couch is prohibitively difficult, and I didn’t have space to get rid of it. I was able to play with two people, but it was a bit cramped, and I felt like I needed more distance from the TV the whole time.
See that above me? Yeah, it's a ceiling fan.
The consideration I didn’t think of is what’s above. Needless to say, you need space to flail your arms around, especially if you’re tall. Above me within arm’s reach is a ceiling fan. That’s a serious problem if you get excited and jump with your arms above your head, as my girlfriend experienced a few minutes into our first session of Kinect Adventures. Ultimately, I can’t blame Kinect for my living room being small, but you need to be aware of the space constraints - Kinect won’t work in dorm rooms or tiny play areas, but does work with at least average sized living rooms. It’s entirely constrained by the field of view of the sensor and CGH, and admittedly it’s hard to make very wide angle CGH systems with good uniformity and repeatability.
I later tried Kinect in a much larger space with more than 12’ of space behind a wall-mounted plasma, with the Kinect mounted atop the display about 6.5’ above the ground. I had much more success here both with detection of my feet, and two-player space.
If you’re running out of space or are playing with just barely enough, the problems that arise are what you’d expect. Kinect won’t see your feet very well, or miss your hands, but thankfully most of the time you’re given feedback visually on the display that you need to move back into the optimal position.
The interesting bit of the Kinect space story is that closer to the sensor, you get better depth resolution at the cost of having less space to work in, yet far away you sacrifice depth resolution for more working area. It’s a simple consequence of field of view and the angular separation of those points in the CGH image. Prime Sense advertises that their reference design has a depth resolution of 1 cm at two meters from the sensor. As you move further away, that depth resolution gets worse (larger).
The final note is that I’ve actually noticed that clothing choice makes a difference. In fact, there are a few warnings in the literature shipped with games which notes that some clothing choices may make detection hard. I never had serious issues being detected outside of one special combination of cargo shorts and a specific footwork-heavy move in Dance Central, but more on that later. Common sense applies here, and essentially you need to look human and have some depth contrast visible for Kinect to detect your limbs.
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Aloonatic - Friday, December 10, 2010 - link
I come from the UK, where we have very expensive homes that somehow still have average room sizes that are so small that Guantánamo Bay residents would think that their lodgings were spacious loft apartments in comparison, so I was wandering if anyone has tried tinkering with the placement of Kinect?As every inch counts (no sniggering at the back) has anyone tried placing this on a wall mounting above and behind a TV? I'm guessing that there might be issues with the TV itself obscuring the device's field of view, but it might just work if moved high enough?
Love the idea of Kinect, and could just about find the space as recommended on the box, but I am not sure that I have the room that Anand recommends. :(
Oh, and will Kinect be used on the next generation xBox too? Might have to wait for Kinect 2, which will hopefully work in smaller rooms, if there ever is such a device.
DesktopMan - Friday, December 10, 2010 - link
Original release Wiimote only had a 3-axis accelerometer. Motion plus didn't add a three-axis gyro until 2009. Even calling it six-axis with the gyro is stretching the definition of six-axis as it can't detect motion with constant speed unless the IR camera is pointing towards the motion bar. (Same is true for the PS3 "6-axis" controller of course. It's not six axis, it's 3-axis accelerometer and 3-axis gyro.)DesktopMan - Friday, December 10, 2010 - link
Motion bar should of course have been sensor bar. Why is there no edit button ;)gvaley - Friday, December 10, 2010 - link
There are all in all 3 (three) axes in a three dimensional world and this is exactly what we are existing in. Everything else is marketing nonsense.DesktopMan - Friday, December 10, 2010 - link
Quite. Though this is what they're actually somewhat referring to:http://en.wikipedia.org/wiki/Six_degrees_of_freedo...
But neither wiimote with motion plus nor ps3 6-axis actually allows you to track all types of motion in 3 dimensions. So it's false either way :)
gvaley - Friday, December 10, 2010 - link
Imagine if marketers actually respected the principals of the language, "do not use a random expression in lieu of another expression just because it's shorter" for one. "Degrees of freedom" is quite different from "axes." All robots boo.landerf - Friday, December 10, 2010 - link
Is the lag due to processing or camera frame rate? As i understand it the 360 does the processing with a cap of 10% cpu usage. So I'd then assume on the pc it could have better response time. Also can it be powered by usb 3 and or 2 on the pc? Without the need for the power plug.brundleflyguy - Friday, December 10, 2010 - link
I notice in the review it says "On the other hand, there's no possible way that Kinect would ever work in the average dorm room - you really do need 9' - 12' behind the TV to play with two people." Do you mean "in front of the TV"?I'm wondering because I'm using a projector. The projector is about five feet behind me on the ceiling, and the Xbox would be about four feet behind me. The wall on which I projected is about 10 feet in front of me. Would this setup work for the Kinect?
Thanks,
Jim
Gonemad - Friday, December 10, 2010 - link
My guess is, if you are using a projector, you should put Kinect in front of you... if there is enough cable length.Those applications that take a picture of your face would be taking a picture of your... haircut?
Good point! Inquiring minds...
Now, from what I could understand... Kinect will fit right in places that have pool tables, basketball courts, large mess halls... places with plenty of room. My condo has a gym, it wouldn't be misplaced there. So much for enjoying private gaming at home. This thing would fit right in old style arcades!
On another note, kids jumping in apartments... think about that.
Well, the Wii had lanyards, to prevent damage to your TV. Can you attach lanyards to your limbs?
Trolling possibilities / funny ideas:
1- Your pedantic little brother rushes behind you, just to throw Kinetic off.
2- Your mom learns learns how to shutdown your Xbox by talking to it, if she ever reads this article.
3- Trash talking... with your hips. Girls know that pretty well. Do the chicken dance!
4- Not only air guitar and air drums... air orchestra. Air violin. FTW.
Scary thoughts:
1a. Hackers find a way into Kinect and can record you at home.
1b. You hack into your own Kinect and turn it into a full fledged PTZ surveillance camera.
1c. You find out that you can build your own Kinect with industrial cameras, and it will work 20 times better... at 200 times the cost.
1d. You find out that you can use Kinect outside a Xbox360, cutting costs in special cameras for industrial inspection (that cost above $20k easily).
1e. You find out you could have done everything Kinect does with a regular webcam, and a range finder pulled from a parking sensor, costing you just 10 bucks.
1f. Fighting games? Judo? Karate? Jiu-Jitsu? Tae-kwon-do? Be sure your boots are strapped tight. Roundhouse-kick your sofa's gotta hurt. Street Fighter 7?
SlyNine - Friday, December 10, 2010 - link
"Your pedantic little brother " are you sure you know what that word means ? Seems to me little brothers would be less then pedantic, unless your little brother is an egg head.