model keypoints

[Mikec]

Is there a LAStool that creates model keypoints (mass points) from classified ground points?

[Martin Isenburg]

Hello,

depends what you need the keypoints for. For quicker visualization purposes of a triangulated ground TIN? Or for final product computations. There is a "simple" way to thin out your ground points into keypoints but that does not provide any error guarantees.

lasthin -i in.laz -ignore_class 1 3 4 5 6 7 9 -classify_as 8 -step 2.0 -o out.laz

this assumes you have no other classfications than the ground class 2 and those ignored ones 1 3 4 5 6 7 9. This will essentially relassify the lowest ground point per 2 by 2 meter cell as a keypoints. This will give fast and okay results for faster visuals but  the subset of keypoints should not really be used for high-qualtiy DTM generation (unless you need DTMs, say, twice as coarse as the step.

Regards,

Martin @rapidlasso

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http://rapidlasso.com - fast tools to thin your LiDARs

On Fri, Mar 27, 2015 at 10:58 PM, Mikec <mike....@gmail.com> wrote:

Is there a LAStool that creates model keypoints (mass points) from classified ground points?

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[Mikec]

Thank you for the reply Martin. Actually, I was hoping there was a routine similar to Terrascan's Model Keypoints routine where the goal is to basically thin out the ground classified points to retain only the "important" points for creating a TIN based on setting tolerances. Any chance this capability could be added in future?

[Mark N.]

I agree with Mikec, this would be a very useful feature for all of us.

I think, after the ground algorithm could be an option which re-iterates 

through the points and looks whether there is a sudden thickening vertical sense or not. These areas include the "important" points I guess. 

[bslaughter]

Hello Mikec,

Did you ever get a reply from Martin regarding this issue?

Thank you,

Brian

[Jeffrey Osborne]

Check out the adaptive thinning option in lasthin https://groups.google.com/d/msg/lastools/sToPDXIwLIE/-OzOACpZAgAJ