[GRASS-user] newbie: processing lidar with r.in.xyz

Hamish hamish_b at yahoo.com
Wed May 28 23:28:08 EDT 2008

andrew haywood wrote:
> i am currently enjoying the flexibility of using r.in.xyz
> to process lidar data over native forests in Victoria, Australia.
> Thank you hamish for such a great tool.

cheers, it is always nice to hear what it is used for.

> At this stage I have 'binned' my data into 20m cells and calculated
> a number of metrics (including 13 vegetation height percentiles p5
> p10 p20 .. p90, p95, p99) based on the z values.
> What I was wondering is how can I calculate the mean intensity for
> the associated height percentiles.

Just pass the intensity as the z= column instead of the height column?
That is why I called it "Column number of data values in input file" instead of "elevation values". It doesn't know/care what the data means.

> To get around this I have written a script in a proprietary
> stats package to create the intensity metrics. However, I would
> prefer to use Grass and opensource tools to do this binning

what sort of metrics are you after?

> Any suggestions would be appreciated!!!!
> My data is in the following format
> x|y|ground|intensity|class|canopy_top|height
> 410774.45|5820999.93|773.3|23|10|766.0983886719|7.20161
> 410763.07|5820999.9|802.27|2|10|763.9434814453|38.3265
> 410765.47|5820999.94|773.11|90|10|764.2877807617|8.82222
> 410758.09|5820999.95|807.99|47|10|762.8372192383|45.1528
> 410748.12|5820999.93|760.89|8|10|760.5731811523|0.316819
> ...
> I suspect I should start to learn python.

time well spent regardless; good return on investment if you like to think like that.

a nice place to start:
  10 minutes Python tutorial for programmers of other languages

you could probably do what you want quite simply in awk as well, but I'd only really suggest that if you know UNIX or C already.



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