Skull Cave LiDAR Point Cloud - TubeX

LiDAR scans were taken inside and outside the lava tube. Outside of the tube, the tripod was set up such that the scanner was between 1.5 and 2.5 m tall. Inside the tube the tripod was sometimes as short as 0.5 m. The VZ-400 is a near infrared (1550 nm) scanner. Geometric control was achieved using a pair of Trimble RB GPS antennae, one mounted on the LiDAR scanner (rover) and the other setup as a base station. In outside scans, before taking a LiDAR scan, the VZ-400 would use the GPSs to fix a real time kinematic (RTK) solution for the scanner’s location and then use that position (scan position) as a reference for LiDAR returns. Scan Positions were determined for in-tube scans (where GPS lock is not possible) in post processing by ensuring there was significant overlap between scans taken with GPS information and scans inside the mouth of a tube. Post processing was done using RIScan-Pro version 2 (scanner specific software). Also, in post-processing, overlapping areas of point clouds were merged and inaccuracies in roll, pitch and yaw, were resolved using a multi station adjustment routine and the data were projected in UTM coordinates. Once post processed, data were exported in “.las” format with LiDAR reflectance (infrared) saved as intensity. The point cloud is georeferenced and projected in UTM Zone 10 North and generally has < 1 cm point spacing, however spacing varies locally and depending on the distance from the scanner to the target. All data for Skull Cave are within a bounding box with the following WGS84 corner point coordinates: -121.51402,41.72896,-121.50808,41.73344.