Units of boundingVolume box

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mholt...@gmail.com

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Feb 19, 2020, 10:24:04 AM2/19/20
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In https://github.com/CesiumGS/3d-tiles/tree/master/specification#box each indices is described, but what is the unit of the values of a boundingVolume box, e.g.

   0,   0,   10,
    100, 0,   0,
    0,   100, 0,
    0,   0,   10
  ]
Does this mean, the center of the box is 10m above the ground, 100m in each direction of x-axis and 100m in each direction of y-axis and 10m in each z-direction?

And how is this boundingVolume box located on the right position on the globe then?

Omar Shehata

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Feb 19, 2020, 11:02:07 AM2/19/20
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These are X,Y,Z in cartesian ECEF coordinates, see: https://en.wikipedia.org/wiki/ECEF

So this box as given would not be above ground, it would be very close to the center of the Earth. What you would do to position this on the surface of the globe is by defining a tileset transform matrix to position it at the right global location. See:


Alternatively, a boundingVolume region lets you specify the volume in geographic coordinates:


The tileset transform matrix does not apply to "region". 
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