# shadow simulation from buildings [duplicate]

is it possible to use hillshade function in ArcMap to calculate shadow areas of buildings or simulate shadows of buildings, using DSM of the buildings and the sun angle and azimuth?

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## marked as duplicate by whuber♦May 18 '15 at 15:47

Please edit your first question if you need to change something. If you just want to add the tags, don't worry because I have done that for you. – Nathan W Nov 10 '10 at 12:52
This question, in its second form (using building data and sun information) was eventually answered at gis.stackexchange.com/questions/17155. – whuber May 18 '15 at 15:46

ArcGIS claims to be able to do this at 10 with new 3D Analyst tools: Virtual City Template Enables 3D City Modeling. I say claims because I haven't personally used these tools yet. Here's the documentation for the tool discussed in that article: How Skyline Barrier (3D Analyst) works

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hi how about trying to use sketchup?
i did not do it so if you do let us know how it went

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Not in Arcgis, but the free SAGA GIS can calculate the shade of objects in a digital surface model: http://www.saga-gis.org/saga_modules_doc/ta_lighting/ta_lighting_00.html Use the analytical hillshading method with the ray-tracing option. All values >90 degrees (>1.56 radians) are shadows (black in the sample figure below).

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What you are trying to do is usually called 'solar envelope computation'. This paper present a method to compute it:

Eugenio Morello, Carlo Ratti, Sunscapes: `Solar envelopes' and the analysis of urban DEMs, Computers, Environment and Urban Systems, Volume 33, Issue 1, January 2009, Pages 26-34, ISSN 0198-9715, DOI: 10.1016/j.compenvurbsys.2008.09.005.

Solar envelope computation seems far more complex and different than hill shading. Hill shading usually only uses the orientation, and do not fully model light rays propagation.

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Sketchup works great. You can define all kinds of settings and create time-lapse animations. Using ArcGIS, you can convert DSM to TIN then TIN to Multipatch and COLLADA and load into SketchUp.

In fact back in 2006 even ESRI was acknowledging the SketchUp was the tools for this: Quoting "Users can rapidly develop three-dimensional models that are georeferenced, animate scenes, and produce shadow casting studies for proposed building."

Take a look at the article: http://www.esri.com/news/arcuser/0207/urban.html It only applies to ArcGIS version 9.3.1 and older as this is the last version where the SketchUp6 plugin can be installed. In fact, for your purposes (DSM) it would probably be easier to use the plugin to convert the TIN surface to SketchUp then the new way which requires a few more steps. (The benefit of using the older version is that you can also export vector features (polylines, polygons, points) from ArcGIS to SketchUp whereas in version 10 this is not possible)

As was already mentioned in the previous similar post, ESRI claims to have similar functionality but I have not tried the tools personally.

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Hello swingley,eliavs and jukub thanks for your suggestions, but i think none of your suggestions will get me the right results. perhaps you didn't get the question so i refer you to this article:a-a-r-s.org/acrs/proceeding/ACRS2002/Papers/VHR02-2.pdf. for you to get the picture. At page 3, section 3.2 Shadow simulation: this not so much to read, only a few sentence and figure 5. "Shadow simulation image" depicts exactly what i intended to achieve. perhaps, if anyone has experience solving such a task would be grateful if you could explain a little bit for me. thanks in advance. – Yudine Nov 11 '10 at 13:37
The actual answer to your initial question is no. You cannot use the hillshade function to obtain the shadows. Personally I don't have a very high option of the paper you mention; Aside from the numerous items that just don't make sense, the purpose is to recover information hidden in the shadow areas? Why not use an image taken from a different angle, time of day, etc. I disagree that none of our suggestions will give you the results depicted in figure 5. I will add another answer with some quick sketchup screen captures. – Jakub Nov 11 '10 at 14:56

"but i think none of your suggestions will get me the right results."

I still think you should consider the new ESRI tools or Sketchup. As for Sketchup, you can customize what object cast shadows on what objects. If you just want the shadows themselves -> view model in plan view and un-check perspective -> then paint model white on white background and in Style dialog turn off edges. See below for 2 examples of this; 1: buildings, 2: terrain. You can export this to tiff, import into ArcGIS or other GIS, georeference, classify, convert to polygons if need be.

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Hello jukub, i really did not mean that... I just want to thank you....you've made my day. – Yudine Nov 11 '10 at 17:20