- natgeo Jackson County Alabama. Video by @salvarezphoto I've been building a cave. Well a virtual one at least. It's part of a proof of concept project to see if we can use images to build very accurate 3D maps of underground spaces. This 3D map is constructed of 1200 individual high resolution images. This looks like drone video but it's a virtual camera "flying" through a digital replica of a real world cave. The technology is called photogrammetry. The potential of this technology for understanding, interpreting, preserving, and exploring the world is incredible.