Unable to get center of the screen coordinates

CesiumJS
1

I have a set of coordinates return from an api. Thereafter, I set camera view with the following codes:

viewer.scene.camera.setView({
		destination:  
                     Cesium.Cartesian3.fromDegrees(103.84958233542338,1.3669641300494784, 100),
		orientation: new Cesium.HeadingPitchRoll(0, 0, 0),
		endTransform: Cesium.Matrix4.IDENTITY
});

Now, I want to get center of the screen and return its coordinates. But I am unable to do so. Any idea why?

var windowPosition = new Cesium.Cartesian2(viewer.container.clientWidth / 2, viewer.container.clientHeight / 2);
      var pickRay = viewer.scene.camera.getPickRay(windowPosition);
      var pickPosition = viewer.scene.globe.pick(pickRay, viewer.scene);
      var pickPositionCartographic = viewer.scene.globe.ellipsoid.cartesianToCartographic(pickPosition);
      var apilon = pickPositionCartographic.longitude * (180 / Math.PI);
      var apilat = pickPositionCartographic.latitude * (180 / Math.PI);
2

The code you posted worked for me. Are you getting an error?

3

I am getting the error “cartisean is required”. I am not sure is it the Lat and Lon format returned from an api to set the camera position. Thereafter, I would like to use the new camera position to get the center of the screen.

4

Ok, the reason it doesn’t work in this particular case is the center of the screen is a point in the sky, which has no 3D world position.

If you just need to get the camera position, use viewer.camera.position.

5

After using viewer.camera.position, how can I convert it back to 2D format for lon& lat to parse into my API URL.

6

Convert from Cartesian3 to longitude/latitude: https://cesium.com/docs/cesiumjs-ref-doc/Cartographic.html?classFilter=Cartogr#.fromCartesian