[OSGeo Africa] Potential Solar Radiation

Jaco Engelbrecht Jaco at bolandkelder.co.za
Wed Mar 11 06:22:10 PDT 2015

Hallo Hanlie

To be honest, I have no idea how the extension in ARCGIS works. It is part of the spatial analysis package. I will read up on the r.sun thanks.

I think I've found the problem with the aspect. When I created the DEM, I just imported the vector line data. Someone told me that when they make the DEM in ARCGIS, they use line and point data. I have both, how to I use both to create the DEM in with GRASS?

Thanks for the reply :)

C: +27 82 801 3299
E:  jaco at bolandkelder.co.za
T:  +27 21 862 6190
F:  +27 86 521 6147
W: www.bolandcellar.co.za

-----Original Message-----
From: africa-bounces at lists.osgeo.org [mailto:africa-bounces at lists.osgeo.org] On Behalf Of Hanlie Pretorius
Sent: 11 March 2015 07:55 AM
To: africa at lists.osgeo.org
Subject: Re: [OSGeo Africa] Potential Solar Radiation

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.

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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