EuroSpeleo 2016

Poor man's laser scanner, a simple method in 3d cave surveying

Oral|Dr Attila Gáti

Abstract

We present our new 3D cave surveying technique and software, Poor Man's Laser Scanner (PMLS). Our method is based on splay shots performed with Beat Heeb's DistoX or similar laser distance meter equipped with compass and inclinometer. The sampled points should be distributed in all directions on all over the walls visible from the stations. Utilizing a robust and reliable surface reconstruction algorithm, our software interpolates the measured points with a watertight surface, which is free of self-intersections.
We have found that even complicated geometric layouts can be recovered with good detail from as few as 50 to 150 splay shots per station. Our 3D models are more accurate and realistic than those generated by already existing, widespread cave mapping programs like Compass or Therion. To be able to exploit the excellent 3D visualizing capabilities of the free software Blender (www.blender.org), we implemented our algorithm as a Blender add-on.
We have surveyed Bányász cave, the deepest cave in Hungary, completely with impressive results. Using a tripod and a special DistoX firmware upgrade by Beat Heeb made on site work fast and convenient. The 3D model of the cave and further details about our method can be found on our website: cave3d.org.