[GRASS-user] r.sun and XY locations

[Daniel Lee]

Hi Christian,

Determining the position of the sun relative to a given pixel requires
knowing the pixel's latitude at the very least. That's why using r.sun in
an XY location won't work. r.sun definitely needs a geographic location to
work with - otherwise it doesn't know which way is north and south and
where the sun's at at a given time of day or year.

Best,
Daniel

--

B.Sc. Daniel Lee
Geschäftsführung für Forschung und Entwicklung
ISIS - International Solar Information Solutions GbR
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2012/8/8 Christian Braun <Christian.Braun at tudor.lu>

> Dear all,
>
> I want to create a WPS module which is calculating solar irradiance. As
> WPS architecture I have to use PyWPS which is creating a XY-location and
> mapsets on the fly to process the data.
>
> What is the current status of running r.sun in a XY location? On a testing
> machine I got back an error message [1] while providing latitude and
> longtiude grids to the r.sun command [2]. Is it feasible at all?
>
> I am aware of the setting in PyWPS to have the GRASS processing done in a
> predefined GRASS location, but this is not an option because of how the WPS
> should work.
>
> Greetings from Luxembourg,
> Christian
>
>
>
> [1]
> WARNING: <PROJ_INFO> file not found for location <XY>
> ERROR: Can't get projection info of current location
>
> [2]
> r.sun -s elevin=ro_dsm latin=ro_latitude longin=ro_longitude lin=3
> alb=0.17 beam_rad=ro_irra_B_hc diff_rad=ro_irra_D_hc glob_rad=ro_irra_G_hc
> day=180 step=1
>
>
> ------------------------------------------------------------
> Christian Braun
> R+D Engineer
> Environmental Modelling, Geocomputation
>
> Tel: +352- 425991-6608
> Mobil: +49-179-6845896
> Mail: christian.braun at tudor.lu
>
> Resource Centre for Environmental Technologies,
> Public Research Centre Henri Tudor,
> Technoport Schlassgoart,
> 66 rue de Luxembourg,
> P.O. BOX 144,
> L-4002 Esch-sur-Alzette, Luxembourg
>
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