Cesium.GeoserverTerrainProvider

Geoserver uploaded DEM data to cesium.
But the DEM comes out weird.
Please tell me how to fix this

-souces-

terrainProvider : new Cesium.GeoserverTerrainProvider ({
** url : “http://localhost:8090/geoserver/sf/wms”,**
** layerName :“sejong_dem_1”,**
** maxLevel: 11,**
** heightMapWidth: 64,**
** heightMapHeight: 64,**
** })**

-image refence-