[GRASS-user] R.basin - feet?

[Margherita Di Leo]

Mark,

On Mon, Feb 4, 2013 at 3:38 PM, Mark Seibel <mseibel at gmail.com> wrote:

> Following-up to my earlier post...
>
>> I'm working in coord system feet and DEM units feet.
>>
>> I ran r.basin on a stream basin, and I noticed that it reports the basin
>> max/min elevation in meters, however, the values are really feet.
>>
>> Has anyone done this with units of feet?  I see the program do feet/meter
>> conversion when running, but maybe that is just for the coord system units.
>> (?)
>>
>
> I realize this only applies to a fraction of participants, but maybe it
> would help someone.
>
> I noticed language in the r.sim.sediment and r.sim.water modules which
> mention that the horizontal units are converted to meters.  It also states
> that the elevation needs to be in meters.
>
> Using coordinate system of feet, but DEM units of meters for r.basin, I
> verified that at least two parameters are correctly calculated:  Stream
> length and basin elevations.
>
> If I use DEM units of feet, it reports that the elevations are in meters,
> but the values are actually feet.
>
> Please note I have not confirmed the findings in the actual source code,
> just from some quick observations of the module output.
>

Thank you for your comments. As r.basin relies on a bunch of modules, and
since I'm not really close to the matter of feet, I can't provide any
answer. BTW, it seems to me that the issue that you raised is of general
interest for GRASS, because it would be nice to guarantee a consistency
among the modules, or at the very least document how they behave in this
regard.

Thanks
MaDi

>
>
>

-- 
Margherita DI LEO
Postdoctoral Researcher

European Commission - DG JRC
Institute for Environment and Sustainability (IES). Unit H03 – FRC
Via Fermi, 2749
I-21027 Ispra (VA) - Italy - TP 261

Tel. +39 0332 78 3600
margherita.di-leo at jrc.ec.europa.eu

Disclaimer: The views expressed are purely those of the writer and may not
in any circumstance be regarded as stating an official position of the
European Commission.
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