Forum Discussion
mechamania
11 years agoHonored Guest
How to use Oculus on motion platform
Hi
I would like to use the Oculus Rift inside a flight simulator. The flight simulator is based on a 6 DOF motion platform. We need to use the relative positon of the Oculus to the cabine. Not relative to the outside world. This because the cabin may make some movements that are not reflected in the 3D world. So we can not use the acceleration meters and gyroscope. But the new Oculus has a camera for position tracking and that seems perfect. But when the camera information is combined with the acceleration sensor and gyroscope, it will not work. The camera works relative to the cabin while the acceleration sensor and gyroscope will work relative to the world.
So the question is: Can I only use the position tracking bassed on the camera and ignore the other sensors? Will that work? Will that be accurate enough and will the motion range be ok? What for instance when looking 90 degrees left or right? Does the camera track this? Can I use multiple cameras to increase the range?
I would like to use the Oculus Rift inside a flight simulator. The flight simulator is based on a 6 DOF motion platform. We need to use the relative positon of the Oculus to the cabine. Not relative to the outside world. This because the cabin may make some movements that are not reflected in the 3D world. So we can not use the acceleration meters and gyroscope. But the new Oculus has a camera for position tracking and that seems perfect. But when the camera information is combined with the acceleration sensor and gyroscope, it will not work. The camera works relative to the cabin while the acceleration sensor and gyroscope will work relative to the world.
So the question is: Can I only use the position tracking bassed on the camera and ignore the other sensors? Will that work? Will that be accurate enough and will the motion range be ok? What for instance when looking 90 degrees left or right? Does the camera track this? Can I use multiple cameras to increase the range?
12 Replies
- MannyLectroExplorerWhy don't you simply put the camera on the motion platform ? This way it will move with it.
- KydDynoMyteHonored GuestI think putting the camera on the motion platform is what he is talking about.
It should work, but if the oculus camera doesn't allow it you could always use something else like freetrack with a wiimote or playstation camera. - mechamaniaHonored GuestYes, putting the camera on the motion platform (inside the cabin) is what I would like to do.
The question is if the input of the camera is enough, If Oculus is combining the input of camera with the accelerometer and gyroscope, then there will be a problem. I can imagine the accelerometer and or gyroscope are needed to get the needed resolution or to get a fast response. And maybe the accelerometer and gyroscope result in a larger range. - PathogenDavidHonored GuestI don't think it is clear yet exactly how position tracking from the camera will be blended with the sensors on the headset, but I'm sure they will be tied in some way.
I would expect that you will have to re-do the sensor fusion bits in the LibOVR yourself if you want to do something like this, because accelerations caused by the platform would make the accelerometer "think" you moved your head when really only the platform moved. You basically would have to counteract any physical changes caused by the motion platform from the sensor readings.
Unfortunately, the extent of what you have to do won't be clear until the updated LibOVR comes out. - KydDynoMyteHonored GuestI wouldn't be at all surprised if the camera was used for all 6dof tracking (no drift problems) and the other sensors on the rift would only be used when the LEDs are out of view of the camera. Especially if they made their own camera. The PS3 eye at 120 fps works pretty smooth with freetrack. Hopefully the oculus camera will have an even better resolution and framerate.
- PathogenDavidHonored GuestKydDynoMyte:
No word on resolution, but the camera is only 60 FPS according to http://www.oculus.com/dk2/
I imagine that the sensors will be used for the most up-to-date information and then the camera will be used only to correct drift.
Honestly, I feel that 60 Hz is often enough if all it is really for is drift correction. Resolution matters though since it will lower resolution means lower accuracy, worse with distance from camera.
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In fact, once you exceed 60 Hz for the camera, you start running into bandwidth issues. Assuming that it is basically a dumb webcam, and no compression: A 1280 x 720 image at 60 FPS with a single 8-bit color channel takes ~53 MB/s (assuming no compression) which already exceeds the USB 2.0 spec of 35 MB/s.
The PlayStation Eye (PS3 camera) can only do 640 x 480 at 60 Hz according to Wikipedia. Since it is known that the PlayStation Move system relies on color, we can assume they are transmitting color down the wire. For 640 by 480 @ 60 FPS and 16 bits per pixel (IE: 5R6G5B) we get about 35 MB/s, which matches the USB 2.0 spec! Perhaps that is a coincidence though, because 320x240 @ 120 Hz (the other mode the camera supports) is far under the USB 2.0 spec, but the use of 320x240 might just be because it is what the camera likes, and not because it is the highest resolution possible at 120 Hz.
The PlayStation Camera (PS4 camera) supports much better, but uses a proprietary connector so we don't know what the medium is. Its not too far-fetched to assume it is USB 3.0, which could definitely handle 1280 x 800 @ 60 Hz x 2 cameras (468 MB/s, just under the USB 3.0 spec of 500 MB/s)
Now Oculus could use USB 3.0, but I imagine they don't want to throw USB 2.0 users out the window, or they found that increased resolution was not useful enough to justify it.
If I were to hazard a guess, the Oculus camera will only be 1024 * 600 @ 60 FPS (this is about 35 MB/s raw 8 bpp.)
TL;DR: The camera is going to be limited by the bandwidth of USB 2.0 for anything above 1024 x 600.
(Obviously there are lots of variables to consider, so this is all speculation. For all we know its a 4K camera and the image processing is done on the camera its self, although I personally doubt both of those possibilities.) - KydDynoMyteHonored Guestwell not just drift correction,the camera will be used for all positional tracking, right? I am really surprised at the 60hz.
- PathogenDavidHonored GuestYou can do really basic positional tracking with an accelerometer, it just becomes inaccurate very quickly. I imagine they use the accelerometer for position changes in-between updates from the camera.
- mechamaniaHonored GuestIf camera is only used to compensate for drift and fast response is mainly from accelerometer and gyroscope, then I probably can not use it. I will have to add my own tracking.
- GraffinHonored GuestI think that you can use some kind of software correction to compensate the data from the accelerometer.
Something like dynamic initial state of of the glasses.
If the platform is tilted 10° to the east, you just compensate that rotating the view in the oculus 10° to the opposite side.
Sorry for my English, I don't know if you are going to understand what I'm trying to explain. :/
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