Material for Ground Primitive

Hello everyone,
I am using Cesium in a project and lately I am trying to use ground primitive to display some data on Earth.

On QGIS this is what I get :
QGIS Capture

But when i try to do the same on CesiumJS, this is what i get:
CesiumJS Capture

Do you know how I can change the parameters of Material or MaterialApparence so that my rendering in CeisumJS looks like the one in Google Earth?

The goal is to remove “the blur” that can be seen inside the texture.

Thanks in advance !