Lighthouse Question about Coordinate Difference- Set-up Without HMD

Discussions related to positioning systems where the position is calculated outside the Crazyflie and sent to the device using radio, including MoCap systems
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jamesphopper
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Joined: Sun Feb 02, 2020 11:37 pm

Lighthouse Question about Coordinate Difference- Set-up Without HMD

Post by jamesphopper » Sun Feb 02, 2020 11:56 pm

Hello!

I'm using (2) V1 stations and a HTC hand controller to set up my lighthouse positioning system (Crazyflie 2.1 / Bitcraze VM / Windows 10 / Intel i7 9th gen / Nvidia geforce 2060).

It's written on the lighthouse wiki that:
"Note: If you have a setup without HMD and you want to set the origin of the space on the floor, you can open the get_bs_position.py script and modify the top of it to set “CENTER_AROUND_CONTROLLER = True”. Be aware that this will put the SteamVR and your space out of sync, so none of the example using the SteamVR coordinate will work correctly."

Are the coordinates out of sync due to the shape of the controller vs. the headset when placed on the floor, or is it because of how the headset 'quick' calibrates? To the point: can this difference be measured and then adjusted for in the example scripts?

Thanks-



arnaud
Bitcraze
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Joined: Tue Feb 06, 2007 12:36 pm

Re: Lighthouse Question about Coordinate Difference- Set-up Without HMD

Post by arnaud » Mon Feb 03, 2020 11:08 am

The coordinate are 'out of sync' because the openVR space has its origin in one of the base station and the Crazyflie space will have its origin where the controller was placed. So there will be an offset between the positions estimated in steamVR and in Crazylfie. This will not be a problem as long as you do not want to use openVR position estimates together with the Crazyflie. This is done so that the space has the floor at ~0.

The difference with a HMD, is that with a HMD you can tell streamVR to set the origin of the space in the HDM, this allows to get a setup where both steamVR and Crazyflie have the same space with the floor at ~0.

So this has nothing to do with geometry or precision, this is only about how steamVR can be setup without HMD.

jamesphopper
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Posts: 6
Joined: Sun Feb 02, 2020 11:37 pm

Re: Lighthouse Question about Coordinate Difference- Set-up Without HMD

Post by jamesphopper » Mon Feb 03, 2020 11:25 pm

Ok! Thanks for the clarification.

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