[OSGeo Africa] Potential Solar Radiation

[Gavin Fleming]

Hi Jaco

On 11/03/2015 07:55, Hanlie Pretorius wrote:
> Hi Jaco,
>
> I didn't reply yesterday because I was hoping that someone with more
> knowledge than I have, would.
>
> I need some clarification before I can possibly help you.
>
> 1. What do you mean by 'make a radiation map'? What is the original
> data source? I know of some people who have gotten irradiation data
> for the whole of Africa off the Internet and then it's just a question
> of displaying it.
>
> Or is this also something that you are using your DEM for? Then I
> would look at GRASS GIS's r.sun function -
> http://grass.osgeo.org/grass64/manuals/r.sun.html.
Yes that should do what you need. Note GRASS 7.0 has been released.

More GRASS links:
http://grass.osgeo.org/grass70/manuals/addons/r.sun.daily.html
http://grasswiki.osgeo.org/wiki/Energy_calculations

There's also
http://www.saga-gis.org/saga_module_doc/2.1.3/ta_lighting_2.html. You
can run SAGA standalone, command line or through QGIS. Or even through
R: http://artax.karlin.mff.cuni.cz/r-help/library/RSAGA/html/rsaga.pisr.html

Here's a worked example
https://darrenwiens.wordpress.com/tag/solar-radiation/
>
> 2. In my limited experience with creating DEMs it looks like your DEM
> has a hole at the top and that is why your slope map does as well. I
> think this has to do with defining soft and hard break lines when the
> DEM is generated. What procedure did you follow to create your DEM
> from the 5m contours?
Yes please let us know what steps you used.

Here's a nice worked example in GRASS:
http://www.ing.unitn.it/~grass/docs/tutorial_641_en/htdocs/esercitazione/dtm/dtm1.html
>
>
Gavin
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