WHAT’S IN A NAME? USING HANDHELD LIDAR TO VISUALIZE HISTORIC INSCRIPTIONS IN A VIRGINIA SHOW CAVE

Located in Cave Hill, Grand Caverns is a National Natural Landmark and the oldest continuously operating show cave in the United States. Past historical analysis was mainly based on 19^th and 20^th century documents as well as signatures left by past visitors in the caverns. This ongoing study uses a light detection and ranging (Lidar) device which is handheld, allowing for simultaneous location and mapping (SLAM), an essential feature for creating point clouds in caverns. This device is used to scan a historically relevant part of Grand Caverns known as the Ballroom. From the 1830s through the early 1900s, thousands of candles were put in the Ballroom for the Grand Illumination Ball, a seasonal event that hundreds of visitors attended. This room in particular has many signatures and is of special sociocultural significance to Grand Caverns’ longstanding history of tourism. Despite the value of show caves, consistent human interaction with caverns can lead to degradation of the cavern itself, with the potential to harm the valuable features inside. This all underscores the need for a standardized method of surveying and assessing cave features, whether they are anthropogenic or geologic in origin.

The primary objective of this ongoing study is to develop a standardized method for cave feature assessment using Lidar, specifically applied to data recorded about signatures in the Ballroom. First, working with a set of 96 signatures in the Ballroom which each included a four digit year (e.g. 1806) written alongside it, we collected categorical data (year, name, etc.) and connected individual signatures to specific locations using the Lidar device. Additionally, we collected 6 control points outside the cave entrance to georeference the signature locations. Lastly, the effect of scan time on point cloud quality was assessed by comparing ~1 minute and ~20 minute scans. Future investigation may involve repeated scans with revised methods, such as allowing more time for data collection. Additionally, historical resources related to Grand Caverns will be analyzed to evaluate potential relations to the broader history of Grottoes, VA and the Shenandoah Valley. Development of a reliable method of obtaining reference points which are easily linked to categorical data could result in a standardized method to be employed elsewhere.