public void generateLodEntropies() {
        float[] entropies = new float[getMaxLod()+1];
        for (int i = 0; i <= getMaxLod(); i++){
            int curLod = (int) Math.pow(2, i);
            IndexBuffer idxB = geomap.writeIndexArrayLodDiff(curLod, false, false, false, false, totalSize);
            Buffer ib = idxB.getBuffer();
            entropies[i] = EntropyComputeUtil.computeLodEntropy(mesh, ib);
        }

        lodEntropy = entropies;
    }
This calculation is slow, so don't use it often.
jme3-terrain/src/main/java/com/jme3/terrain/geomipmap/TerrainPatch.java