Understanding World Tracking System and Limitations


I’ve been testing things, and been experiencing both success and oddness. I am running into a few issues, and I wonder if I could get some clarification to help me design …

** How does World Tracking stick your assets to the ground and keep track of where you are in relation to it?
-Does it take a picture of the ground and use that as a reference?
-Does it use GPS to determine where you are?
-Does it use the accelerometer to determine where you are based on speed and direction of your movement relative to where it thinks you place the assets?

**What’s the best practice for placing an object on the ground?
-Is a gridded surface most likely to give the best result, like a tiled floor?
-If you are in the park and the grass is a little bumpy, is this going to create a problem with world tracking and keeping your assets stable and in place?
-Should I be looking for instances of floor meeting walls at right angles - does that help determine what is flat?

**I’m reading about “anchors” in the documentation. It seems to suggest that we can place custom anchors to help keep a world tracking experience more stable. Is there more information about this that I missed? There was no link from that article to info about creating custom anchors, and a search of the documentation didn’t bring it up.

Here’s a bit of Info about my tests. Some things I’ve done so far…

I made an easy plane based chalk drawing of the Chartres Cathedral’s floor labyrinth pattern, and sized it quite large … perhaps 20m x 20m. I took it to the park and walked through it on the grass. It seemed fairly stable, though I didn’t walk it’s full path.

I tweaked the hallway maze I had made earlier when World tracking was dangled temptingly in front of us before it was implemented. And it seemed to work nicely with world tracking in my home. It’s difficiult to test things this large inside, and I tried in my driveway with some success. I couldn’t tell if it was moving oddly as I moved, but there were times when I suspected it wasn’t exactly where it should have been.

I put together a set of gothic hall pieces to make something quite large and mazey. So far, I have a hall that turns, and decided to test it outside tonight. It’s a bit late, and dark out there. I thought I might be able to get some streelight illumination on my street or in the park to get started to lay down the assets to the ground properly. But I ran into problems with the model not staying properly in place after it had locked to the ground. At times, it moved away from me as I walked towards it, and I expect this to be because of poor lighting conditions.


I was going to ask about anchors as well.
When I was playing I found you can look up from underneath the model. Whitch I thought was cool.



Also … it’s too bad … but completely understandable … that the darkness or dimness of an outside evening environment inhibits world tracking placement.

Delicately lit environments look so amazing when there is darkness around my personal device. I have to brighten up the lighting to see it out in regular daylight, but then it loses drama. It’s also kind of fun to think of gatherings in the evening in the park to experience these things.

I wonder if it would be possible to create a grid in the grass with solar lighting that is close to the ground, and if this would work with world tracking? Thoughts from those in the know?


Cheers @shawnjoh for the interesting insights and comments there - much appreciated. Some of our most ‘in the know’ faces from the Forum are currently away in the sunnier climbs of California this week due to attending AWE 2019, but we’ll get back to the points we can answer as soon as possible. But should be able to get a fuller reply once our AWE exiles are back in the office so appreciate your patience :slight_smile:.


Hi @shawnjoh,

Studio uses a process called visual inertial odometry to recognize key features in the user’s environment. These key features are then ‘recorded’ when the device is moved around and a ground plane is determined based on this information.

For the world tracking subsymbol built into Studio, once a ‘good’ quality ground plane is detected the searching of key features is turned off and the ground plane is ‘saved’. A content placement state is then initiated which uses hit testing (a raycaster coming from the device’s screen working out where it is intersecting the ground plane) to position an anchor on the ground. Content is then placed relative to this anchor point, ensuring it stays tracked to that specific position over time.

We are still playing around with custom anchors ourselves and working out the limitations of adding multiple to a scene, but we will be sure to document our findings.

Similar to image tracking, world tracking involves image analysis. Image analysis requires a clear image. Tracking quality is reduced when the camera can’t see details, such as when the camera is pointed at a blank wall or the scene is too dark. You will need to bear this in mind when creating a world tracking experience.

Please let us know if you have any further questions regarding world tracking.

All the best.



Thanks @George , I’ve read through this a few times and it has been helpful.