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Space grows when deserializing WorldAnchorTransferBatch based on a bigger space but...

stepan_stulovstepan_stulov ✭✭✭
edited December 2017 in Questions And Answers

Hello everyone.

Full question title should have been:

Space grows when deserializing WorldAnchorTransferBatch based on a bigger space but without learning more of the environment.

I have noticed an interesting and somewhat unexpected behaviour that I would like to be commented on or clarified. This is all based on Unity.

Here is a step-by-step reproduction of what I did:

  1. Clear the current space in the settings.
  2. Make sure to walk around enough so that the newly created space grows to a bigger size. In my case it was some 45mb.
  3. In an app create some good number of objects, say 200, objects with world anchors, construct a WorldAnchorTransferBatch of them, serialize it and save it to disk.
  4. No remove the space in the settings again and do not walk around much but make sure your space is somewhat smaller. In my case it was 19mb.
  5. Now launch a app that loads that previous WorldAnchorTransferBatch, deserializes it and creates a game object for each anchor in it. Anchors work and objects snap in place.
  6. Now check the size of the space in settings. It's back to the bigger size that that WorldAnchorTrnasferBatch was based on despite the fact that your head absolutely did no travel around enough to provide the additional extra size of the space.

This leads me to a couple of speculations:

  1. When unpacking a WorldAnchorTransferBatch the system recognizes that the smaller and the bigger are two versions of the same space and simply merges the two enriching the smaller one. This conclusions seems more likely to me.
  2. The space doesn't just contain the spatial data but also the anchors in some form. This conclusion seems less likely to me due to the very temporary nature of anchors. Space can't contain every anchor.

I welcome everybody to share their objections, ideas or plain better conclusions to why the space grows upon deserializing a WorldAnchorTransferBatch without really learning more about the environment.


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  • Alright, so let me ask the next questions:

    (1) Is it possible to walk the space on one and define the room, freeze it to a file (or snag the file that was created) and save that to a server so that every future execution or headsets joining the environment can begin their experience with the same room definition each time? If so, where would I find that file?

    (2) Is this observation valid for both the Hololens and the Full Immersion Headset?

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