Focal mean filter window size	Airborne LiDAR DSM	DTM from filter 3 × 3	DTM from filter 7 × 7	DTM from filter 15 × 15	DTM from filter 21 × 21	DTM from filter 25 × 25	DTM from filter 31 × 31	DTM from filter 35 × 35	DTM from filter 41 × 41
Statistical quantity	Airborne LiDAR DSM	DTM from filter 3 × 3	DTM from filter 7 × 7	DTM from filter 15 × 15	DTM from filter 21 × 21	DTM from filter 25 × 25	DTM from filter 31 × 31	DTM from filter 35 × 35	DTM from filter 41 × 41
Min. (m)	165.259	168.355	200.914	239.984	245.254	245.435	245.553	245.636	245.750
Max. (m)	292.764	290.246	289.328	288.654	286.975	286.516	284.712	283.665	282.209
Range (m)	127.504	121.890	88.414	48.670	41.720	41.081	39.159	38.028	36.459
Mean (m)	265.289	265.289	265.289	265.289	265.290	265.290	265.290	265.289	265.289
Median (m)	265.381	265.417	265.495	265.605	265.667	265.698	265.744	265.768	265.801
Root Mean Square (m)	265.425	265.424	265.421	265.417	265.414	265.413	265.411	265.410	265.408
Standard Deviation (m)	8.487	8.441	8.368	8.228	8.140	8.089	8.023	7.986	7.937
Skewness (m)	−0.318	−0.326	−0.339	−0.370	−0.391	−0.403	−0.416	−0.423	−0.430
Kurtosis (m)	2.595	2.561	2.493	2.445	2.425	2.413	2.397	2.388	2.377