urban elevations from DEM data?

[martinvk]

I was looking at some baseboards made from DEM data and noticed that the urban elevations seemed a bit weird. Then it occurred to me that the original data must have read the tops of buildings as the ground elevation and so I was seeing the city as if a giant blanket had been put over it, propped up by the buildings.

Can anyone confirm that this is what actual happens? Do the tree tops in forested areas also define the elevation?

 

[cascaderailroad]

I would imagine that treetops and built up areas are off in all the x-y-z elevations of -/+ 20' in all dirrections...and most probably much, much more.

 

[geophil]

Can anyone confirm that this is what actual happens? Do the tree tops in forested areas also define the elevation?

Yes, with SRTM this is often the case. Terrestrial DEMs are much better here, but not available for free in our part of the world.