I have a question how do you model a whole city because that is a really tough challenge for me. I can’t seem to find out the height of things can anybody help me out?
there is a script that can create blocks that resembles builds for you. i THINK it’s called disconfabulator (sp!!!) or something.
Also, another way is to make the blender file public and get everybody to add something to the city. 
Depends on what he needs the city for. I can imagine he needs individual buildings and some low-detail streets and such.
What’s your goal with the city? Ask yourself that question and then you can decide how to model it. Cities the way I said are quite a lot of work, but rewarding nevertheless.
It’s actually the discombobulator. It makes quite good buildings for something like a shot from a helicopter or something, but for a closer shot like someone walking down the street you would need to make them yourself or download some.
You see I’m making a city and I want to make a new York thing with roads leading to places. I want to know how to do that you know. Especially with the roads and stuff I thought UV editing might work I’ll think of something.
In that case you should make your own. On some sites like Turbosquid you can download some free stuff like buildings.
Being an architecture student who recently had to model an area of a city out of chipboard, I would recommend actually walking around(no joke) and estimating the heights.You probably only need rough estimates(within 5 feet or so).
A good method for estimating is about ten feet for every floor of a building. Just count the floors and multiply by ten. Depending on the architecture each story may be a little bigger, i.e. victorian houses are about 13 feet per story. Feel free to measure in meters instead of feet, I understand that our measuring system is very outdated in the United States.
You can print out an image from Google Earth(which can also give you approximate widths and lengths) and walk around and estimate the heights.
Or try that new live maps site by msn, they have photos of the buildings of cities close enough and at an angle at which you can count the stories.
My class spent days trying to find the heights an easier way. Google is making a 3d map of San Francisco, where I live, but unfortunately I don’t know how to get a hold of their 3d building models(which are made in SketchUp), so that I can just measure the models.
Hope that helps. : )
Check this out:
Yo man I wish I saw this forum before I started because I started with the planes with curves and cut them out. It is a little hard to explain but when it is done i’LL POST IT (I cant show you it with color because it slows my computer down okay.
Thanks you guys are such a help to me everytime I post anyway tomorrow I’ll show you what I did Okay. ANyways tell me again how to post my .blend file so I can show you.
Here is the one we made for the crosswalk project.
Its good for refrence, or you are free to use it its an open file. Just give credit to the blenderprojects team 
There’s a number of free file hosting services, you upload the blend to them then put the link in your post here. I use esnips.com but there are at least half a dozen others.
The way I did this is to take photos and using a reference dimention calc the other bits. Watch out of perspective and forshortening but the ‘window’ idea is a good one
If you are wanting something more precise then your in the world of theodolites etc - I think if you try to get hold of blueprints you’d be paid a visit by the FBI/CIA in todays climate
I was unable to find any info on modeling an existing city. There’s plenty on creating random city-like models, but I needed a semi-accurate model, more accurate than the floor count estimates and less accurate than expensive theodolites would provide.
I had my boss buy one of these babies:
http://www.robotoolz.com/RT-9000/RT-9000.html
occassionally after work (dusk to night makes the laser much easier to see) I wander the city with a camera, the tool, and a tripod. I take photos of buildings and measure heights in increments marking where the measurement was taken on aerial photos, ground photos, parcel and street centerline drawings provided by the county for free.
I can measure the heights with triangulation (Yay pythagorean theorem!) and get a fairly close estimate of building heights as well as other measurements that come in handy (Heights of floors that change heights, distances between pillars, etc.). The laser tool even has a function for deriving perpendicular height so you don’t have to do the math.
Then I model boxes in sketchup pro to scale (it’s faster untill I find a blender way to simply key in dimensions while push/pull modeling). Then I bring it into blender for details.
This may not be the best way, but I couldn’t find anything better.
Also, depending on the city, be careful walking around with a camera and a laser, and measuring buildings, especially government buildings. I get a lot of ‘looks’ and have had to explain myself before.