How are building placed and positionned when I put them in cesium ?

I have the following gltf :
I would like to use it in cesium directly, without passing in ions, so I uploaded it on a server, get the data of the model, then do this :
(this code is working, and is not the part I need help with, it’s just here for background on the question)

type IModel {
data: any,
position: {logintude: number; latitude: number: height: number;}

private loadModels(model: IModel) {
let modelInitialPosition = new Cesium.Cartographic((model.position.longitude || 0), (model.position.latitude || 0), (model.position.height || 0))

this.altimeterService.getElevation(modelInitialPosition).subscribe(elevation => {
    const position = {
        height: model.position.height + elevation
    const cModel = new Cesium.Model({
        gltf: modelData,
        modelMatrix: Cesium.Transforms.eastNorthUpToFixedFrame(Cesium.Ellipsoid.WGS84.cartographicToCartesian(MissionUtils.toCesiumCartographic(position))),
        scale : 1.0


getElevation(pos: Cesium.Cartographic): Observable {
return new Observable(observer => {
const promise = Cesium.sampleTerrainMostDetailed(this.terrainProvider, [new Cesium.Cartographic(pos.longitude, pos.latitude, 0)]);
Cesium.when(promise, (updatedPositions) => { => {[0].height);


**So sorry for the long block but basically, the model has a default longitude, latitude and height. But the height is relative to the ground. Since I am using Cesium World Terrain, I am adding the terrain elevation to the model height, and then I draw it.
The problem I face with the method above tho, is the center point of the model. I do not know what Cesium consider the center of a model, and where does he put the axis.
Exemple :
If you open the model with gltf reader, or with windows built in gltf reader, the model will be placed correctly like this : **

**But if I put the same model in cesium I end up with the following :**so when I apply my change, now the model will be in the hair and not on the ground (but the center point where the axis are drawn is correctly on the ground) .

So my question is, how is this “anchor point” calculated ?
I don’t know if you need more help.

So to resume my question, my anchor point is correctly placed, but my model is displayed far from that anchor point.
When I upload my model in different gltf viewer or even in cesium ion, the anchor point will mbe moved at the center of the model, but not when loading my asset like I am doing up, what I am missing ?

CesiumJS retains the origin defined in your model. Your model’s vertices are not centered around the (0, 0, 0) point which is why it looks that way.

I explained a similar issue in this GitHub comment:

Does hosting it on ion not work for your model?

Thanks for the reply. Yes, it works great in cesium Ions, but as you say, it get re normalized.

So yes, I believe vertices are not centered, but the problem is the customer are asking me what they have to change cause in their opinion the model is correct… but I have no idea what they are doing wrong.
I will point out to your answers.

and search some ‘renormalizer’ online if there is any