Get z of a given point

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Sebastián Barría

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Feb 4, 2022, 3:39:25 AMFeb 4
to LAStools - efficient tools for LiDAR processing
Hi everyone.
I have a laz file and I need to find the z of a given point (for example the z of the bounding box's center).

I need to know where is the floor, so I suppose I should get the z of a specific x,y in a specific classification... maybe the highest point or the lowest.

Does anyone knows how to get it... using LasTools or any other tool?
Please, help!!!

Thanks

Support at rapidlasso

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Feb 4, 2022, 3:40:37 AMFeb 4
to LAStools - efficient tools for LiDAR processing
Hi Sebastian,
the question is a bit unspecific.

lasinfo -i your_file.laz

is a good point to start - to see whats in the file - e.g. you see the boundaries of the point cloud.
If you want to get the z value of a certain point you can use

las2las
with one option out of "Filter points based on their coordinates." -> see the las2las readme.
There you can get the values of a specific area, classification,...
With -o ... you can output this as plain text.

If you are not used to LiDAR and lastools much you may read also the tutorials found at
https://rapidlasso.de/rapislasso-tutorials/
and
https://rapidlasso.com/category/tutorials/

If you have further questions see
https://rapidlasso.de/service/
to enable a good support.

Best,

Jochen @rapidlasso   

Kirk Waters - NOAA Federal

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Feb 4, 2022, 6:31:46 AMFeb 4
to LAStools - efficient command line tools for LIDAR processing
I think interpolated value at a given x,y,z is essentially what lascontrol is doing. If you were to use control points that are your x,y locations with a zero height, then the difference lascontrol calculates is going to be the height you want (or perhaps negative of it).  

If you're looking for highest or lowest points, that's a different question and assumes an area of interest, not at a single x,y,z location. Subsetting your points to the area and classes of interest and running lasinfo as suggested would work.

Kirk


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