Intensity layers: Two intensity layers were generated fromthe first and last return measurements, respectively (Fig. 2).The natural neighbor interpolation method in ArcGIS 3-Danalyst was used to generate the two 1-m spatial resolutionintensity layers. The mean and standard deviation of intensityfrom first returns were 7.83 and 5.99, respectively, with therange of 0.10 to 472.82; and those from last returns were 9.17and 5.31, respectively, with the range of 0.14 to 502.32.