locally modify terrain

On my project in localhost I need to modify a litle bit portion of terrain that overlap in some point my tileset.

I try with Cesium.HeightmapTerrainData****but I don’t have any result.

var viewer = new Cesium.Viewer(‘cesiumContainer’, {

terrainProvider: Cesium.createWorldTerrain()

});

viewer.camera.setView({

destination : Cesium.Cartesian3.fromDegrees(9.111672,39.218, 400),

orientation: {

heading : 0,

pitch : -0.5,

roll : 0.0

}

});

var rect = new Cesium.Rectangle.fromDegrees(9.111672,39.219757, 9.118092, 39.227483);

var height = 2;

// a flat piece of terrain

var terrainData = new Cesium.HeightmapTerrainData({

buffer : new Float32Array([height, height, height, height]),

width : 2,

height : 2

});

var tileset = viewer.scene.primitives.add(

new Cesium.Cesium3DTileset({

url: ‘ca-dataset/tileset.json’

})

);

I expect that in the “rect” the terrain is flat to 2m height but nothing.

There are any solutions?

Thanks in advance.