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I'm not an expert in GIS, I learnt it recently, and I'm trying to improve my skills.

I'm trying to calculate the loss of solar radiation at a specific point due to surrounding topography. I'm basically trying to understand how to do what is explained on ArcGIS help website: http://desktop.arcgis.com/en/arcmap/latest/tools/spatial-analyst-toolbox/modeling-solar-radiation.htm

I have also found this paper that achieves exactly what I would like to do: http://www.esri.com/news/arcuser/0309/files/solar.pdf

My issue is that I don't understand the process.

So far, I have managed to:

  • Generate a viewshed (from a point and a DEM): I've got a raster that shows me what area of the sky is not visible (a mountain range at the horizon).
  • Generate a skymap for diffuse radiation calculation: I've got a raster with time of the year and time of the day.
  • Generate a sunmap for the period I want to know, for direct radiation calculation.

In theory, I understand I have to overlay my viewshed raster with my skymap. The ratio will show me the loss of diffused radiation. Same for the sunmap for direct radiation.

But I have no idea how to do it. ArcGIS help about equations is too complicated for me, I would like to know how to do it in ArcGIS. I don't understand the values of my generated rasters, and I'm not sure they are sufficient to calculate what I want.

I would also like to be precise that I don't intend to calculate radiation for an area yet. Only for a point now, and the only outcome I want is a loss ratio for both diffuse and direct radiation.

Other question: once I have done it, how can I add scales and axis to the graph generated by ArcGIS? Is there a way to do it with ArcMap or it's a Photoshop thing?

closed as unclear what you're asking by jbchurchill, Vince, whyzar, PolyGeo Feb 25 '17 at 5:30

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • this more of a pointer, not a complete answer: I don't have ArcGIS to give you specific directions but search for Raster Calculator ArcGIS, essentially you pick 2 input layers (which would need to be of the same spatial extent) and use them to create a new output layer, where the output layer = input1/input2 for example. do you have a background in remote sensing? – Alex Feb 24 '17 at 17:58
  • I think you should try and focus on the first step that ceased to make sense to you and write what you were trying to do, what you actually did and what went astray with that. Forget your "Other question" to avoid this one being closed as too broad. You are stuck before that and as per the Tour there should be only one question asked per question. – PolyGeo Feb 25 '17 at 5:33