Re: [GRASS-user] Re: i.sunhours

2010-01-26 Thread Hamish
Tim Michelsen schrieb:
   what do the inputs for i.sunshine in GRASS7 mean?
  
   i.sunhours doy=name lat=name
  
Achim:
  I guess
  
  doy = day of year
  
  lat = latitude
  
  While doy in (1-365)
  And lat in (0-90)?
  
  Should be. But why name??
 
Timmie:
 I thought the same.
 
 But the doc is strange:
 
 doy=name
 Name of the doy input map
 

DOY is day of year, and it is a raster map, but I'm not sure if
it should be 0-365, 1-366, 1-365, 0-365.25, ...

a lot of the other GIPE modules (grass-addons) use that, but I have
no idea why it wants those to be in raster maps instead of just a
single integer day or floating point day+hours/24+minutes/1440.

maybe it is intended for satellite passes where there could be a
different time-of-day as the sat passes overhead or for multiple
passes on the same image? ?? no idea.


also from our tests with r.sun I'm not sure how much time a pre-formed
lat= map really saves vs. calculating it e.g. once per raster row with
the proj library, or even calculating for each individual cell on-the-
fly. see  https://trac.osgeo.org/grass/ticket/498, the r.sun page in the
wiki, and the threads on the -dev mailing list about it.


the documentation does need a lot of enhancement.. perhaps there is more
documentation in the GIPE section of the addons SVN? there are some
examples there anyway.

it seems the modules still need a bit of GRASSification done to them too.


Hamish



  
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Re: [GRASS-user] Re: i.sunhours

2010-01-25 Thread Achim Kisseler

Ah, so maybe you can have different doy on every raster-cell?

Generating a map full of 45-integers would give you valentines day hours 
of sunshine everywhere on the map..., guess.


Achim

Tim Michelsen schrieb:

I guess

doy = day of year

I thought the same.

But the doc is strange:

doy=name
Name of the doy input map

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