link the virtual object to a car

kzhang3

If we use the Hololens in a car, the holograms will be left behind when the car moves. Can we linked the holograms to the car?

HoloSheep

@kzhang3

The Health & Safety warnings that come with the device do specifically mention not to use the device while driving:

Do not use HoloLens when a full field of view and attention are needed for safety, such as while operating a vehicle or doing other potentially hazardous activities.

If you are a passenger in the car, it might depend on whether you are looking outside or inside the car when the app initializes and sets the main world anchor. It would also depend if you first did a significant scan of the interior and then kept enough of the interior of the car in view of the sensors so that the device was potentially able to keep track of itself in that space. For example it might work better from the back seat where the seats are in view.

Then there might also be an issue if the gyroscopes play a significant role in the HPU's calculation of movement within the world where the acceleration of the vehicle might trick the device into thinking it is moving further and faster than the sensors indicate.

Have you tried using the device as a passenger in the back seat?

HoloSheep

@kzhang3

The Health & Safety warnings that come with the device do specifically mention not to use the device while driving:

Do not use HoloLens when a full field of view and attention are needed for safety, such as while operating a vehicle or doing other potentially hazardous activities.

If you are a passenger in the car, it might depend on whether you are looking outside or inside the car when the app initializes and sets the main world anchor. It would also depend if you first did a significant scan of the interior and then kept enough of the interior of the car in view of the sensors so that the device was potentially able to keep track of itself in that space. For example it might work better from the back seat where the seats are in view.

Then there might also be an issue if the gyroscopes play a significant role in the HPU's calculation of movement within the world where the acceleration of the vehicle might trick the device into thinking it is moving further and faster than the sensors indicate.

Have you tried using the device as a passenger in the back seat?

DennisWelu

I have this same area of interest and have been experimenting a bit. The application in question will be a machine with an operator in a cab, but same concept. What I have observed is this:

1. The holograms from the Holograms app "want" to stay in the cab. But too much movement and they disappear while the device rescans. Sometimes is seems to say "ah, we're in the same room" so it puts the hologram back in place. But soon or later (typically not too long) the device actually gets quite messed up. The scanning stops working, ghost images, even orientation of messages are off. Toggling the HL off and on seems to reset it and the hologram appears again.
2. I then set up a test project with SpatialMapping on board and used TapToPlace to place a cube in the same basic place. This does not work as well as the holograms app. The cube disappears pretty quick and never comes back, at least in the few tests I ran. In fact the scanning just stopped and the meshes were gone. And then I discovered, as I was sitting in my car in front of my house (end of dead end street, its ok) with the HL on, if I glanced back to the house there was a mesh inside and my cube was sitting on it! I got out of the card and walked inside and found my cube in the kitchen. Quite strange really. I tried reducing the scan Extents to 2.5 on the SpatialMappingObserver but that didn't seem to help.

As you thought, @HoloSheep , the gyros definitely seem to play a role in causing problems for this scenario.

I'm trying to find a way to keep holograms placed inside the cab in place even as the machine moves around. I looked at attached frames of reference but this appears only available in the DirectX implementation and not directly as an option in Unity C# scripts (with some work could be made to work together I suppose but might be easier to just do something in C# with coord transforms etc.).

Would love to hear ideas on how to make this happen. Have been looking at Vuforia objects but from what people are saying there is an unacceptable lag in the position updates there. I have a 3d model of the "stock" cab that could be used but unsure how to accurately relate that to the user viewpoint especially if the idea is to use that model instead of the observed spatial landscape. Seems like you'd still have to make some observations to orient it correctly etc.