byte[] _data = new byte[3];

// Splat index takes the first 4 bits
// Height takes the remaining 4 bits
_data[0] = (byte)((_splatIndex << 4) | _height);

// Scenery index takes the first 4 bits
// Part of type index takes the remaining 4 bits
_data[1] = (byte)((_sceneryIndex << 4) | ((_typeIndex & 0xFF00) >> 8));

// Part of type index takes an additional 8 bits
_data[2] = (byte)(_typeIndex & 0xFF);