CONSTRUCTING HIGH-RESOLUTION POINT CLOUDS OF BUTLER CAVE TO SUPPORT PALEOCLIMATE RESEARCH

Butler Cave in Virginia was first discovered in 1958, the geomorphology of the cave consists of extensive natural underground passages and chambers. The most recent cave survey was in 1985 and produced a plan view map. Despite the years of study of this cave, a comprehensive three-dimensional map of the cave system has not been created. Therefore, our study aims to produce a three-dimensional map of Butler Cave using the handheld LiDAR-SLAM and produce a detailed high resolution cave map to assess cave deformation and its geomorphology. LiDAR is a technology that creates maps of unknowledge areas and can determine location inside of the map. These devices use infrared lasers that reflect off surfaces and return to the sensor, measuring the time of flight. The range and resolution of a LiDAR sensor directly affects the accuracy and detail of the generated maps, as well as the performance of localization within those maps. The higher the resolution, the better the point clouds can be provided, allowing for the identification of smaller or more complex landmarks in the environment. With this information that LiDAR-SLAM provides, is possible to generate a geometrical representation of the cave and construct a high-definition point cloud with a millimeter resolution obtained using the LiDAR and its capabilities (range is 100 meters, 300x10⁶ scanner points per second and a rotating field of view). Post-data analysis includes using SLAM (simultaneous localization and mapping) technology to obtain the point cloud and since is a large cave, merging the different scans was required to complete the map. As a preliminary results, we completed scanning more than 1.5km of passage. The scans were divided into sections, each one of the sections means a difference scan and it was possible to register a change in elevation of 108m. The goal of this study is to construct a comprehensive map of Butler Cave to find candidates (e.g. speleothems) for paleoclimate reconstruction in addition, we hope that this work contextualizes in depth what are the paleoclimate archives recording by providing georeferencing to meteorological observations. Finally, a three-dimensional map of the cave will be given to the Butler Cave Conservation Society for future studies.

This investigation was under the program of UROCK, sponsored by NSF.