[OSGeo Africa] Potential Solar Radiation

Hanlie Pretorius hanlie.pretorius at gmail.com
Tue Mar 10 22:55:19 PDT 2015

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 -

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?


> From: africa-bounces at lists.osgeo.org [mailto:africa-bounces at lists.osgeo.org]
> On Behalf Of Jaco Engelbrecht
> Sent: 09 March 2015 04:47 PM
> To: africa at lists.osgeo.org
> Subject: [OSGeo Africa] Potential Solar Radiation
> Hello, me again.
> I have two questions today:
> 1.       Is there an easy (and understandable - I'm not a programmer nor a
> GIS expert) way to make Potential Solar Radiation (I think you also call it
> irradiance maps) in QGIS? I know in ARCGIS it isn't too difficult, but I
> don't have ARCGIS and really need to make these maps. Find example attached
> (Original data was made in ARCGIS)
> 2.       I made my own 5m DEM with 5m Contours. How do I smooth out my end
> product of Aspect and Slope (already using Bilinear resampling)? And why is
> there no data to show (as you can see in the middle of the map)? How can I
> get it to fill in that gap, like the one in ARCGIS? (Find example attached)
> Any help would be greatly appreciated.
> Best regards,
> Viticulturist
> C: +27 82 801 3299
> E:  jaco at bolandkelder.co.za<mailto:jaco at bolandkelder.co.za>
> T:  +27 21 862 6190
> F:  +27 86 521 6147
> W: www.bolandcellar.co.za<http://www.bolandcellar.co.za/>

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