# 3D Tile definitions

In the 3D tile definition (https://github.com/AnalyticalGraphicsInc/3d-tiles/tree/master/specification), the properties section of the tileset.json file specifies that a maximum and a minimum value be specified.

In this example https://github.com/AnalyticalGraphicsInc/3d-tiles/blob/master/examples/tileset.json the Latitude, Longitude and Height properties all have a max and min value.

What does this max and min value refer to? 3D Tile spec (first link) mentions that both a max and min are required, but I have no understanding of what those values are.

How does a Lat/Lon have a max and min value? How does Altitude have a max and min value? Which of those two values is the ACTUAL location of the model? Why the need for a range?

And more importantly, if I have a lat/lon and alt values for a model, I how I enter that into the tileset.json file?

Is there further documentation that i haven’t come across that talks more about this, that I haven’t discovered?

Cheers!

If you go to this section you’ll see that it says that :

The properties value in a tileset is an object containing objects for each per-feature property in the tileset.

So these values do not determine the location, but rather they are properties that can be used in styling, picking or other analysis. I think the reason it’s min/max is because these are defined on a tile, not on a model. If I tell you that a tile is at lat/long (20,30), that might mean that there are no buildings at all in that particular location, because a tile can contain one or more tiles and each can contain multiple buildings.

So knowing the min/max values at least tells you that all your buildings are in this area. I hope that answers the first question.

For your second question, if your tileset contains a glTF model which has a coordinate at (0,0,0), this will be placed in the center of the earth, unless you move the tileset in CesiumJS by setting a modelMatrix transform, or by defining a transform for your root tile: