Saturday, January 15, 2022

Automatically generated cave maps from Austria


In August I visited Austria, and was able to hike to the Tischofer höhle and Hyänen höhle caves. Back then, I took 3D scans of the caves. Having worked with automatic construction of cave maps since then, six months later I'm now starting to have a capability to run these models through the Cave Outliner and get plan and cross section views out. Pretty interesting work, by no means done but lets see where this path leads us to!

The basic idea is that one can scan a cave with the iPhone on site, which for small and moderately sized caves happens quickly. And then the resulting 3D model files can be exported to computer, and later processed by the Cave Outliner software to turn them into plan view maps and cross-section images, automatically. The software is not perfect, and neither are typically the scans, so typically some manual adjustments are necessary. However, what's nice about this approach is that it can very quickly produce very realistic shapes of the cave forms, including cross-sections from any number of points.

The generated plan view is above, some tidying was still needed, the final picture is below.  The full maps in PDF, including cross-sections can be found here and here.

The original view at the top has some artefacts that are based on the inaccuracies of the scanning or the sensor:

  • Not all surfaces have been adequately covered, perhaps due to too quick scanning, e.g., near the middle of the entrance to the cave.
  • The walls of the cave have a few mistakes, sudden pins going inside. These are the result of a scanning artefact messing up with the border drawing algorithm.
  • Due to the sensor range limitation (5 meters), the roof near the entrance could not be scanned, hence in the cross section the roof has been estimated. Lack of the roof also means that the usual algorithm for recognising entrances cannot be used in Cave Outliner. However, even when there is a roof (as in the Hyänen höhle), the algorithm is not yet perfect.

Those pictures were for the Tischofer höhle. For the Hyänen höhle they are here:

The 3D models can be looked at directly on your browser here or here. and downloaded from here or here.

This article has also been published at TGR. Read more urban exploration stories from, and other underground stories from Read the full Planetskier series at, or all blog articles from Blogspot or TGR. Photos and text (c) 2021-2022 by Jari Arkko. All rights reserved.

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