Camera direction changes when tracking the entity

CesiumJS
1

Hello, I am trying to load CZML data with CesiumJS and track it with a camera.
However, I’ve noticed that the camera direction changes unexpectedly at times.
This occurs between 47 and 48 seconds in the example below.
Is there something wrong with my CZML document?

    {
        "id": "document",
        "name": "Sample CZML Path",
        "version": "1.0",
        "clock": {
            "interval": "2023-08-30T04:53:40.000Z/2023-08-30T04:53:49.000Z",
            "currentTime": "2023-08-30T04:53:40.000Z",
            "range": "LOOP_STOP"
        }
    },
    {
        "id": "point",
        "position": {
            "interpolationAlgorithm": "LINEAR",
            "referenceFrame": "INERTIAL",
            "epoch": "2023-08-30T04:53:40.000Z",
            "cartesian": [
                0,
                -490613.8372204524,
                6794566.550194831,
                1197650.7113752512,
                1,
                -497815.03522416315,
                6794057.648305954,
                1197570.0578453701,
                2,
                -505595.45068733126,
                6793499.357190209,
                1197481.4231604887,
                3,
                -513187.0977687081,
                6792946.443721257,
                1197393.4960502556,
                4,
                -520583.5334425842,
                6792399.645610031,
                1197306.3985633762,
                5,
                -528558.321575489,
                6791801.325908834,
                1197210.942111075,
                6,
                -535911.9353152977,
                6791241.671116686,
                1197121.518384873,
                7,
                -543209.3039414389,
                6790678.406434525,
                1197031.3847062124,
                8,
                -551387.6752833569,
                6790038.172367605,
                1196928.7851794073,
                9,
                -558775.8923013632,
                6789451.627420369,
                1196834.6555180284
            ]
        },
        "point": {
            "color": {
                "rgba": [255, 255, 255, 128]
            },
            "outlineColor": {
                "rgba": [255, 0, 0, 128]
            },
            "outlineWidth": 3,
            "pixelSize": 15
        }
    }
];

const viewer = new Cesium.Viewer("cesiumContainer", {
  shouldAnimate: true,
});

const dataSource = new Cesium.CzmlDataSource();
dataSource.load(czml).then(function () {
    viewer.trackedEntity = dataSource.entities.getById("point");
});
viewer.dataSources.add(dataSource);

Sandcastle link

2

Hi there,

I’m not sure exactly what’s happening here. It seems to be an issue particularly with this position:

                8,
                -551387.6752833569,
                6790038.172367605,
                1196928.7851794073,

Is there anything unexpected about that position? Otherwise, it might be a bug with our camera controller. If that’s the case, I can go ahead and open a bug in GitHub.

3

Nothing special about that position.
It still happens even if I change it to integer numbers as shown below.
Sandcastle link
So, I think this might be a bug.

4

Thanks for checking. I’ve gone ahead and opened a bug report in GitHub: Camera jumps when tracking entity in inertial reference frame · Issue #11549 · CesiumGS/cesium · GitHub