Slope based 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	165.259	165.259	165.259	165.259	165.259	165.259	165.259	165.259
Max. (m)	292.764	289.281	289.252	286.208	286.179	285.617	285.538	280.444	280.444
Range (m)	127.504	124.022	123.993	120.949	120.920	120.358	120.279	115.185	115.185
Mean (m)	265.289	263.873	263.467	262.912	262.677	262.590	262.530	262.502	262.470
Median (m)	265.381	263.947	263.654	263.263	263.137	263.088	263.049	263.029	263.008
Root Mean Square (m)	265.425	264.002	263.592	263.030	262.792	262.703	262.643	262.615	262.583
Standard Deviation (m)	8.487	8.265	8.116	7.872	7.762	7.727	7.714	7.710	7.707
Skewness (m)	−0.318	−0.267	−0.269	−0.295	−0.313	−0.315	−0.307	−0.301	−0.293
Kurtosis (m)	2.595	2.443	2.436	2.403	2.371	2.357	2.350	2.348	2.347