Airborn Lidar technology has been applied to diverse applications with the advantages of accurate 3D information. Further, Lidar intensity, backscattered signal power, can provid us additional information regarding target's characteristics. Lidar intensity varies by the target reflectance, moisture ...
Airborn Lidar technology has been applied to diverse applications with the advantages of accurate 3D information. Further, Lidar intensity, backscattered signal power, can provid us additional information regarding target's characteristics. Lidar intensity varies by the target reflectance, moisture condition, range, and viewing geometry. This study purposes to generate normalized airborne LiDAR intensity image considering those influential factors such as reflectance, range and geometric/topographic factors (scan angle, ground height, aspect, slope, local incidence angle: LIA). Laser points from one flight line were extracted to simplify the geometric conditions. Laser intensities of sample plots, selected by using a set of reference data and ground survey, werethen statistically analyzed with independent variables. Target reflectance, range between sensor and target, and surface slope were main factors to influence the laser intensity. Intensity of laser points was initially normalized by removing range effect only. However, microsite topographic factor, such as slope angle, was not normalized due to difficulty of automatic calculation.
Airborn Lidar technology has been applied to diverse applications with the advantages of accurate 3D information. Further, Lidar intensity, backscattered signal power, can provid us additional information regarding target's characteristics. Lidar intensity varies by the target reflectance, moisture condition, range, and viewing geometry. This study purposes to generate normalized airborne LiDAR intensity image considering those influential factors such as reflectance, range and geometric/topographic factors (scan angle, ground height, aspect, slope, local incidence angle: LIA). Laser points from one flight line were extracted to simplify the geometric conditions. Laser intensities of sample plots, selected by using a set of reference data and ground survey, werethen statistically analyzed with independent variables. Target reflectance, range between sensor and target, and surface slope were main factors to influence the laser intensity. Intensity of laser points was initially normalized by removing range effect only. However, microsite topographic factor, such as slope angle, was not normalized due to difficulty of automatic calculation.
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가설 설정
In this study, transmitted pulse power was not considered since the transmitted pulse power along a single flight line is the same..
제안 방법
conditions. In this preliminary study, we generated a normalized laser intensity image by removing the range effect. Although the variation of laser intensity over the same target is somewhat reduced after the normalization, the laser intensity is not completely normalized.
As laser signals are backscattered from artificial structures such as buildings, the first and last returns are backscattered at the same location, which are called 'singular returnsHowever, laser signals are transmitted through vegetation canopy, the first and last echoes are recorded separately. In this study, the singular returns are extracted from the laser signals of the one flight line to simplify viewing geometry and transmitted pulse power. Figure 1 shows the high-resolution CCD image that is simultaneously taken with LiDAR overlaid with flight lines.
(2006) tried to calibrate airborne laser intensity obtained from reference tarps with known flying height and atmospheric transmittance. These preliminary studies were mainly focus on the calibration of only effective factors namely, target reflectance and range. Studies on laser intensity have not been delved enough in the respect of viewing geometry, atmospheric condition and surface moisture condition.
This study attempts to normalize intensity by removing range differences based on investigation of the relationship between intensity and geometric/topographic factors such range, LIA(local incidence angel), scan angle, ground height, slope and aspect as well as target reflectance.
대상 데이터
The study area is located in a a mountainous national park in the middle part of South Korea. As seen in Figure 1, major land cover types in this region are forest, rice paddy, other crop lands, and asphalt roads, concrete roads, gravel streets, and dirt roads.
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