@Override
    public void setEnabled(boolean enabled) {
        this.enabled = enabled;
        if (!enabled) {
            // reset the lod levels to max detail for the terrain
            hasResetLod = false;
        } else {
            hasResetLod = true;
            lodCalculator.turnOnLod();
        }
    }
Back on the ogl thread: update the terrain patch geometries
jme3-terrain/src/main/java/com/jme3/terrain/geomipmap/TerrainLodControl.java