Remove high vegetation

[bmeava]

My company deals with earthwork.  We are not interested in the high vegetation.  I would like to reclassify ground points within two feet of all high vegetation points as unclassified to remove incorrectly classified ground points.  Can this be done with LAScanopy or another LAStool?  If yes, please include the required syntax in your response.  Thank you.

[Martin Isenburg]

Hello Gwen,

> I would like to reclassify ground points within two feet of all high vegetation

> points as unclassified to remove incorrectly classified ground points.

There should not be any points classified as "ground" (2) within two feet of points classified as "high vegetation" (5) as those are usually 2 or 5 or more meters above the ground. However, it this happens in your case then I would create an interpolated surface of "lowest high vegetation" points as follow:

:: first find the lowest high veggie point per 2 meter by 2 meter cell and mark it as classification 31

http://rapidlasso.com/lasthin

http://lastools.org/download/lasthin_README.txt

lasthin -i in.laz ^

           -ignore_class 0 1 2 3 4 6 7 8 9 10 11 12 ^

           -step 2 -lowest ^

           -classify_as 31 ^

           -o temp1.laz

:: now mark all points classified as "ground" (2)  that are 2 feet below a triangulated surface of lowest "high vegetation" points (31) into a new classification 30 that you can later map to unclassified.

http://rapidlasso.com/lasheight

http://lastools.org/download/lasheight_README.txt

lasheight -i temp1.laz ^

               -ignore_class 0 1 3 4 5 6 7 8 9 10 11 12 ^                

               -classification 31 ^

               -classify_below -0.6 30 ^

               -o temp2.laz

:: now restore the classifications

http://rapidlasso.com/las2las

http://lastools.org/download/las2las_README.txt

las2las -i temp2.laz ^

            -change_classification_from_to 31 5 ^

            -change_classification_from_to 30 1 ^

            -o out.laz

Regards,

Martin @rapidlasso

On Tue, Apr 4, 2017 at 5:16 PM, bmeava <gar...@biggsandmathews.com> wrote:

My company deals with earthwork.  We are not interested in the high vegetation.  I would like to reclassify ground points within two feet of all high vegetation points as unclassified to remove incorrectly classified ground points.  Can this be done with LAScanopy or another LAStool?  If yes, please include the required syntax in your response.  Thank you.

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[bmeava]

Mr. Isenburg, thank you for your response.

 

My first post wasn’t quite clear.  I want to remove all ground points within 2 horizontal feet of all high vegetation points.  I was able to do this but it didn’t give me the results I wanted.

 

In some densely vegetated areas where there is lower and upper vegetation, the lower vegetation is getting picked up as ground because there are no points on the actual ground.  These false ground points may be a few feet above the actual ground and these false ground points throw off our volume calculations.  Currently, we remove these false ground points manually.  I was hoping to be able to do this with lastools.

 

I am currently experimenting using multiple runs of lasnoise with different settings.  I believe this is the way to go.  But I haven’t achieved the desired result.  There are still a few false ground points that come through.

 

Thank you.