Cave survey
Surveys can be used to compare caves to each other by length, depth and volume, may reveal clues on speleogenesis, provide a spatial reference for other areas of scientific study and assist visitors with route-finding.
The first known plan of a cave dates from 1546, and was of a man-made cavern in tufa called the Stufe di Nerone (Nero's Oven) in Pozzuoli near Naples in Italy.
[3] There are many variations to surveying methodology, but most are based on a similar set of steps which haven't changed fundamentally in 250 years, although the instruments (compass and tape) have become smaller and more accurate.
Since the late 1990s, digital instruments such as distometers have started to change the process, leading to the advent of fully paperless surveying around 2007.
The main variation on the normal methodology detailed below have been devices such as LIDAR and SONAR surveyors that produce a point cloud rather than a series of linked stations.
The stations are temporary fixed locations chosen chiefly for their ease of access and clear sight along the cave passage.
The measurements taken between the stations include: Coincident with recording straight-line data, details of passage dimensions, shape, gradual or sudden changes in elevation, the presence or absence of still or flowing water, the location of notable features and the material on the floor are recorded, often by means of a sketch map.
The cartographer then draws details around the line-plot, using the additional data of passage dimensions, water flow and floor/wall topography recorded at the time, to produce a completed cave survey.
The hydrolevel device used in recent Voronja expeditions comprises a 50-metre (160 ft) transparent tube filled with water, which is coiled or placed on a reel.
The use of computers, inertia systems, and electronic distance finders has been proposed, but few practical underground applications have evolved at present.
A receiving unit on the surface can pinpoint the depth and location of a transmitter in a cave passage by measurement of the geometry of its radio waves.
The centerline data can then be exported in various formats and the cave detail drawn in with various other programmes such as AutoCAD, Adobe Illustrator and Inkscape.
CaveWhere also supports loop closure (using Survex) and provides a user friendly interface for entering and visualizing cave survey data.
The Oregon Caves were scanned from the main public entrance to the 110 exit and were loop surveyed to the point of beginning.
[citation needed] In recent years an underground geographic positioning technology called HORTA has been utilized in the mining industry.
[8] Such automated methods have provided a more than fifty-fold increase in underground surveying productivity with more accurate and finer detail maps as well.
