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I was wondering if anyone knows of a plugin, extension, process, etc. for mapping shadow locations based on date/time using raster data? I have searched and what I have been able to find all seems to require vectors or multipatch data. I have DSM rasters produced from LiDAR and would ultimately like to use those as the source for identifying locations of shadows, as I would like to the surrounding features in the raster to be used as sources of impact (i.e. trees). I am open to all options, but QGIS, Grass, and ArcGIS are preferred.

closed as too broad by PolyGeo Feb 21 '17 at 22:38

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In the QGIS/FOSS world, you can use the GRASS algorithm called r.sunmask.datetime from the Processing toolbox. You provide the date and time, and it creates a shadow mask.

Here's one, derived from Lidar data:-

enter image description here

  • Thank you Steven, that looks exactly like what I am looking for, I will give it a try. Thanks for sharing! – Ryan Garnett Jan 9 '17 at 21:13
  • I am having issues with the command, it is throwing an error. I am choosing to use the date/time, but is seems to be asking for the sun position, etc. Thoughts? (Wed Jan 11 16:35:52 2017) r.sunmask --overwrite elevation=FDD4_ffl@solarLiDAR output=FDD4_ffl_shadow year=2017 month=1 day=11 hour=10 timezone=-5 Using map center coordinates: 314000.000000 4841500.000000 ERROR: Neither sun position nor east/north, date/time/timezone definition are complete (Wed Jan 11 16:35:52 2017) Command finished (0 sec) – Ryan Garnett Jan 11 '17 at 21:36
  • did you use r.sunmask.datetime, or r.sunmask? Also, for r.sunmask.datetime I think you need to provide coordinates for a 'point of interest', e.g. a coordinate somewhere in your raster. You can use the 'copy coordinates' plugin for this (apologies, I think I forgot to mention this step) – Steven Kay Jan 11 '17 at 21:51
  • I used r.sunmask, as I did not see r.sunmask.datetime as an option. I tried it by adding a position, but I am still getting an error: ERROR: Neither sun position nor east/north, date/time/timezone definition are complete – Ryan Garnett Jan 11 '17 at 21:59
  • it's quite possible that r.sunmask.datetime was only added recently to the processing toolkit (i'm on qgis 2.18.1, and grass 7). – Steven Kay Jan 12 '17 at 21:21
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In ArcGIS the tool would be:

Area Solar Radiation (Spatial Analyst > Solar Radiation)

You could also do it in QGIS with the GRASS tool r.sun

I used this tools to create several images along the day from which later I made a video. But now that I reread your question this may not be exactly what you want.

I think what you need is: r.sunmask.datetime or r.sunmask.position

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