Is there a way to get the value (in this question, the NDVI value ranging from -1 to 1) at a specific coordinate of the WebMapTile displayed by addImageryProvider?

I am currently using Cesium ION.
And I registered TIFF file of an NDVI ortho image of a certain region.
This TIFF ortho image is containing a layer of Gray scale NDVI values and a layer of alpha.
I added this TIFF ortho image as a Cesium ION asset.
In the Cesium ION Story, I added the Bing Map Aerial on Cesium World Terrain, and also added the above NDVI imagery tile.
These are displayed without any problems in Cesium ION story.

I would like to ask if it is possible to do the following things

  • Is it possible to get the NDVI value of the specified coordinates of the displayed NDVI imageryLayer?
    Generally, the value is between -1 to 1, or 0 to 1 (gray scale value)
  • Is it possible to acquire the value as the average value of the area enclosed by a certain shape?
  • Is it possible to add an additional layer on top of the NDVI imageryLayer as a layer of vector graphics that changes color according to the NDVI values obtained as described above?

I am now displaying the following code in SandCastle.
Is it possible to add code to achieve the above question?
I will share the code including my token privately if you need.
// Grant CesiumJS access to your ion assets
Cesium.Ion.defaultAccessToken = “my Token”;

const viewer = new Cesium.Viewer(“cesiumContainer”);

const imageryLayer = viewer.imageryLayers.addImageryProvider(
new Cesium.IonImageryProvider({ assetId: 1530141 }

(async () => {
try {
await viewer.zoomTo(imageryLayer);
} catch (error) {