calculate orientation of lines in respect to sun azimuth

01-25-2018 05:44 AM
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New Contributor

I have a dataset that consists of single segment lines, for which I would like to calculate the orientation in respect to the sun at a certain date and time. The lines represent transects that were surveyed in the field and the attribute table contains a date and time stamp for each surveyed transect. I would like to reconstruct the direction of each line with respect to the sun, i.e. whether the surveyor was facing the sun or whether the sun was shining from behind or the side at the time of the survey.

So far, I have only found one possible way to calculate this in ArcGIS, using the sun shadow volume in 3D-analyst. However, this tool only seems to calculate the sun direction for one location at a time. Although it can be used to model the shadow for one feature across a time series, the reverse (model the shadow for multiple points at one specific moment, ideally using the time stamps from the attribute table) is not possible. Does anyone know how to do this? Unfortunately, I have no experience in scripting yet...

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Occasional Contributor

Hi, Joris. You should start here.    Points solar Radiation

Specific questions will arise after digesting all this. Simply put. Knowing the sun's declination in relation to the latitude and exact time of day for each line segment would get you close to your goal.

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New Contributor

Dear Joseph,

Thanks for your suggestion and sorry for my late reply. I hadn't noticed your answer yet. As far as I understand, the Points solar radiation script calculates the radiation for the entire time range and in the given interval for each point in the input data. Since I have several thousand points, each of which has a different observation time, that would mean calculating millions of positions.

Meanwhile, I seem to have found a solution outside ArcGIS. A colleague has offered to write a script for Stellarium.