About the method

What is PMLS?

PMLS stands for Poor Man's Laser Scanner. It's the "work in progress name" of the project. Our goal was to use a single DistoX device for creating 3D cave models.

How does the survey takes place?

Several hundred splay points are measured from every station point. The station points may be identical to those used to survey the centerline of the cave. The splay points are distributed all over the walls visible from the station point.

How it is different from methods using LRUD measurements?

Samples/splay points are not aligned along some line or plane, but distributed in all directions. We may consider PMLS as something between “LRUD” and laser scanning.

How many splay shots are taken from a station?

An order of magnitude of 100 - 1000. It depends on the wanted precision and the complexity of the cave geometry. This order of magnitude is a way smaller than those obtained using TLS. This number results in a rather sparse point cloud on which a surface has to be fitted.

Who is working on the project?

There is a small group of cavers from Hungary contributing to the project. If you want to get involved please write us an email to info@cave3d.org. We also need the help of cavers to test our method worldwide. You may find an "incomplete list" of contributors under the Team menu.

Did you consider other methods like Kinect or stereo photography?

One reason why chose DistoX is that it is on hand. Many cave explorer club owns one or more and use it frequently. It is small and rugged enough. As we use it also to survey the centerline, we don't have to carry extra equipment when doing 3D survey.

What software do you use?

As far as we know there is not any software that is able to reconstruct a surface reliably from such a few measurements. So we are developing our own surface reconstruction algorithm and software.

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