This video explains a basic workflow of creating lines of sight in a 3D environment in ESRI ArcGIS / ArcScene.
It clearly requires adjustments for every specific situation or project.
This video aims simply at giving people who wish to create lines of sight in combination with 3D buildings a head start.

Requirements:
ESRI ArcGIS 10 (in this video mainly ArcScene 10).
3D Analyst (extension).
(Simple) 3D models (in this video: Google SketchUp models).

Requirements for generating lines of sight like in this video:
Multipatch feature layer (to place buildings)
Line feature layer (to draw lines to which lines of sight will be projected; also called 'target features')
Point features layer (including zvalues; to draw points from which lines of sight will be projected; also called 'observation point')

A lot could be improved from this video. This is just to get started.

I tried something similar for a project some time ago and had trouble getting started. Back then, I think I could have used a video like this, so hopefully this is able to help others get going.
Inspired by promotional videos of new features in ArcGIS like the one below, we were motivated to try and work this out. It turned out to be difficult to replicate due to very limited information on what is behind the nice analyses. This video tries to shed some, admittedly limited, light on that.
   • 3D Visualisatie en Analyse in ArcGIS 10  

In case you wonder why I placed the first building in such a curious place, here's a reference to the project I used as an inspiration:
http://www.groningerforum.nl/groninge...

In addition, ArcScene was run on a laptop with (very) limited capacity, not intended for use with ArcGIS, hence the delays in some parts and the very limited visual representation. Again, this video is intended to show a possible workflow, not for promotional purposes of any kind.