Surveying a cave is more than a task, it is the responsibility of every cave diver. Diving into underwater passages and not bringing back any information about them is maybe fun for the divers but completely useless from a community point of view. Having a survey not only gives proof of existence, but gives a better understanding of the cave to both divers and non divers, it allows proper planning of future dives and explorations but also provides an understanding of the hydrology of the area. Not producing or not publishing a survey is only diminishing the value and the recognition that the efforts of cave divers deserve.
Historically survey has been initially a simple stickman representation of the guideline, not of the cave; by reproducing a stickman, the simplest form of survey, divers are able to accomplish already most of the above mentioned objectives. It’s the most basic form of documentation.
Of course it is not a realistic representation of the cave and quite often a proper cartographic representation is the objective cave divers should aim to, even if the time required is impressive and the level of detail that can be achieved is potentially more than what is realistically required.
In the last years the 3D models have become more and more popular as the actually represent the void, and also represent the caves in a way which is ecstatically more appealing. These model require LRUD measurements (side walls, ceiling and floor distance from the guideline) in order to create polygons at each station. Once the software has these data, it connects the stations via interpolation with straight lines.
As a result this form of representation is not very precise or accurate and, despite giving non cave divers a simplified image of the underground space, they definitely cannot be considered accurate or precise representations of the caves.
In order to limit these issues we introduced a system where, at each station, not only LRUD measurements are taken, but also a photo of the cross section of the passage. Importing such images into the software allowed us to draw such cross sections to scale, and have a much more realistic result. Of course interpolation is still happening and the main drawback of the 3D models is still in place.
The amount of time required is growing exponentially with the number of stations and in the end the real question is if this approach is valuable or if it should only be considered an intermediate step between traditional survey and modern approach, with the latter being photogrammetry of the underwater passages.
Exploration of underwater caves is probably the most challenging part of the activities cave divers accomplish, not only because of the unexpected environmental scenarios that can be encountered, but also because it pushes the skills of the divers and the capacity of the whole team. Despite being the dream of many cave divers, nowadays the opportunity for exploration are less and less, especially as the easy access, big passage and crystal clear visibility springs have already been explored and only the most challenging and daunting ones are still available, especially in Europe.
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