Given a terrain and surveyor points sampled from from it or from its contours, is there any algorithm that one can use to simplify the points ( i.e., reduce the surveyor points number) and at the same time retaining the terrain characteristics?

The reason I ask this is because the surveyors may take too much redundant points at flat terrain, and these points serve nothing but to slow down my volume calculation process, so I want them to get filtered out.


Seems like the picking key points portion of generating a TIN could suit your purposes.

Here's a nice discussion on TINs, with three algorithms for picking key points.

Survey of Polygonal Surface Simplification Algorithms would also be a good place to start.

  • Great! This is what I want, any open source code that implement this?
    – Graviton
    Feb 23 '11 at 4:06

There are some extensions of the douglas-peucker filtering algorithm to 3D surfaces. See for example this paper.


Building on wwnick's answer, you can generate a TIN by using the txt2las tool provided with LAStools, then use las2tin (docs) to convert the LAS data into a TIN. Alternatively, you could import your data into GRASS following their instructions on creating a triangle mesh. There's also a simple library tinlib that be worth taking a look at.

  • I am not too sure how can simplify the surveyor points so that I can create minimum number of triangles.
    – Graviton
    Feb 23 '11 at 7:14

i agree with @scw and have some Windows code for you to play with:


the TIN simplification happens in smsimp.exe in your case you would then need to strip the point out of that TIN as your reduce set of surveyor points.



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