[GRASS-user] r.soils.texture question

[Laura Poggio]

Hi Gianluca,
thanks for the explanation. It was very useful. Thanks to your explanations
I managed to modify the DAT file to reproduce the USDA-NRCS texture triangle
<https://www.nrcs.usda.gov/Internet/FSE_MEDIA/nrcs142p2_050619.jpg>. We are
doing some final checks. After that, if you are interested, I can share the
DAT file.

Thanks a lot!
Laura

On Fri, 12 Jun 2020 at 22:27, Gianluca Massei <agr.gianluca.massei at gmail.com>
wrote:

> *.dat files are derived from  TALCPP (
> https://www.tandfonline.com/doi/abs/10.1081/CSS-120017410). The values
> describe polygons coordinates for different class inside the texture
> triangle. In r.soils.texture is implemented an algorithm to check if a
> single point is inside or outside a texture polygon. If the point is
> inside it is labeled with the correspondent texture code and used to build
> a texture map.
> By
>
> Il giorno ven 12 giu 2020 alle ore 08:10 Laura Poggio <
> laura.poggio at gmail.com> ha scritto:
>
>> Dear all,
>> I am looking at the DAT file
>> <https://svn.osgeo.org/grass/grass-addons/grass7/raster/r.soils.texture/scheme/USDA.dat>
>> for USDA soil texture classification for the r.soil.texture addon.
>> I have a couple of questions.
>>
>> 1) the class silt-loam appears twice (number 8 and 12). Is this
>> intentional and needed for the calculations?
>>
>> 2) Could you please explain the structure of the DAT file? As example
>> 1
>> 6
>> 0 0 20 45 45 0
>> 100 60 40 40 55 100
>>
>> First line: I think is the class value as written in the pixel.
>> Second line: not sure
>> Following two lines: I think they are somehow the limits of sand, silt
>> and clay. However I can not really understand in which order.
>>
>> Thank you very much in advance
>> Laura
>>
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>
>
>
> --
> Dott. Gianluca Massei, PhD
>
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