3-D Photo Real Modeling of Devil's Sinkhole in Rocksprings, Texas

Devil's Sinkhole, located northeast of Rocksprings in Edwards County, Texas, was first visited by European settlers in 1867 and is a registered National Landmark and a Texas Parks and Wildlife Department - State Natural Area. The Sinkhole provides a natural exposure of a near vertical >100 m stratigraphic section of the lower Cretaceous, Edwards Group Limestone. Devil's Sinkhole is 107 m deep which makes it the third deepest cave in Texas. It is one of the few caves in the Edwards Plateau that penetrates to the water table. Two freshwater lakes on the perimeter of Devil's Sinkhole are home to two unique crustacean species — an endemic amphipod and a rare aquatic isopod. The walls of the cave support a Mexican fern species found in few other locations in the United States. The walls of the cave are also the summer home to a population of Mexican free-tailed bats whose nightly departures to forage for insects is a significant tourist attraction. When the bats migrate, the sinkhole becomes the home of three to four thousand swallows. The use of LiDAR (Light Detection and Ranging) instruments to map Devil's Sinkhole was initiated in 2005 with volunteer help of cavers from the Texas Cave Management Association and staff members of the Texas Parks and Wildlife Department and Texas Bureau of Economic Geology. This multifaceted project supports a major public outreach program for the Devil's Sinkhole State Natural Area. Access to the pit is limited because of the 42-meter deep vertical drop. The 3-D, LiDAR model will allow visitors to experience a virtual, bat's-eye view tour inside the Sinkhole. The project also offers quantitative data for geological and biological studies of karst terrains. In 2007, Real Earth Models introduced to the Devil's Sinkhole project, a unique process for draping digital photography onto the LiDAR point cloud surface to produce a 3-D Photo Real Model. This process integrates high-resolution LiDAR data and digital photographs to accurately match the actual geology exposed within the Sinkhole. The resultant 3-D Photo Real Model combines the resolution of digital photos (mm scale) with the positional accuracy of cm-scale LiDAR. This model is a life-like, replica of Devil's Sinkhole that can be rotated and viewed from any perspective. The model also allows a precise, quantitative measurement of physical properties, texture and surface features in natural color.