[GRASS-user] Re: grass-user Digest, Vol 25, Issue 61

[Richard Chirgwin]

> ------------------------------
>
> Message: 7
> Date: Thu, 29 May 2008 13:16:04 +1000
> From: "andrew haywood" <ahaywood3 at gmail.com>
> Subject: [GRASS-user] newbie: processing lidar with r.in.xyz
> To: grass-user at lists.osgeo.org
> Message-ID:
> 	<7a4569180805282016s3212c78ck2c35344b95650a7a at mail.gmail.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Dear List,
>
> 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.
> 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.
>
> 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
>
> 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
>   
Andrew,
At the risk of sounding thick, I'd like to know what "intensity" 
represents in your context ... Regarding statistical packages, since R 
is grass-linked, why not do the calcs in R?

Richard Chirgwin
> ...
> ...
> ...
>
> I suspect I should start to learn python.
>
>
> regards
>
> Andy
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: http://lists.osgeo.org/pipermail/grass-user/attachments/20080529/5e7d669e/attachment-0001.html
>
> ------------------------------
>
> Message: 8
> Date: Thu, 29 May 2008 11:17:48 +0800
> From: "maning sambale" <emmanuel.sambale at gmail.com>
> Subject: Re: [GRASS-user] Triangles polygons with Arc*
> To: grass-user <grass-user at lists.osgeo.org>
> Message-ID:
> 	<f902f9840805282017y2bae1830y786aa244a5dc60f6 at mail.gmail.com>
> Content-Type: text/plain; charset=UTF-8
>
>   
>>> Just curious if anybody encountered this issue with Arc*:
>>>       
>> it's a common problem.
>>     
> It does seem to be.
>
>   
>> short answer: TINs stink. Raster maps created from TINs stink more.
>>     
>
> My colleague used SRTM DEM converted to grid format of Arc
> He mentioned that it is fairly common when you convert raster grids in
> arc to vectors (shapefiles).  Especially with very small areas like a
> 2-3 pixels.   Will look into this further.
>
> To all the others who gave me a list of Arc mailing list thanks!  I am
> reading a few right now.
>
> cheers,
>
> maning
>
>