3d tiles boundingvolume box definition


I'm having problems with defining a boundingVolume with a box in the tileset.json for 3d tiles. I'm trying to visualize a cube that has a size/bbox of [0,0,0,1,1,1] which is [minX, minY, minZ, maxX, maxY, maxZ].

My understanding of the specification ( https://github.com/AnalyticalGraphicsInc/3d-tiles/tree/master/specification#box ) is that in case of this cube, the OBB should be defined as below.

0.5, 0.5, 0.5,
0.5, 0.0, 0.0,
0.0, 0.5, 0.0,
0.0, 0.0, 0.5

However, with this definition the boundingVolume is offset from the content (cube). See the attached screenshot, where blue is the boundingVolume, purple is the cube.

I tried all sort of variations on defining the axis for the boundingVolume, but couldn't manage to align it with the content.

I didn't define any transformation in the 3d tiles, just in the Cesium viewer, see below.

var viewer = new Cesium.Viewer('cesiumContainer', {
    globe : false

var modelMatrix2 = Cesium.Transforms.eastNorthUpToFixedFrame(
         Cesium.Cartesian3.fromDegrees(4.367145, 52.011503, 0.0));

var tileset = new Cesium.Cesium3DTileset({ 
    url: 'tileset.json',
    modelMatrix : modelMatrix2,
    debugShowContentBoundingVolume : true,
    debugShowBoundingVolume : false,
    debugWireframe: true


Could you help in figuring out what goes wrong?

Can you share this sample tileset? Uploading it somewhere is fine, or putting it in a Glitch app works to (see this Cesium template https://glitch.com/edit/#!/cesium-template?path=README.md:1:0)

I think the bounding volume is correctly defined, but there might be something else going on with the actual tile content. Is it a b3dm tile?

Thanks for your response.

I put the thing in Glitch, however I didn't manage to get the assets to show up in the Cesium viewer... Nevertheless, I pasted the code that are use for Cesium and also uploaded the tileset. https://glitch.com/edit/#!/join/09e77d94-06e4-4b38-b7e8-be4dfb68bb28

Yes, the tile content is b3dm. I wrote the converter to glb and b3dm myself, so chances are that something could be wrong there :slight_smile: . However, the glb converter seems to be working fine, as the cube or more complex models (eg city models) are visualised correctly.

I used the validator from the validator branch from 3d-tiles-tools (https://github.com/AnalyticalGraphicsInc/3d-tiles-tools/tree/validator) and it returns valid for the b3dm. Is there any other way to verify the b3dm?