On Wed, 23 Aug 2006 11:08:54 +0300
David Baron wrote:
>
> On Wednesday 23 August 2006 07:50, 
> [EMAIL PROTECTED] wrote:
> > n fact, the FAA's Digital Obstruction File is where most of the
> > non-random objects in FlightGear's U.S. scenery come from.  It turns
> > out that there are 444 Iowa wind turbines in the Digital Obstruction
> > File, and thus in FlightGear's scenery (available from the fgfsdb).
> 
> So .. all those wonderful tall buildings which are missing in all those 
> wonderful city sceneries should be around. I would love to make New
> York look like New York :-)

Well, a lot of them *are* around in a way; if you've installed the
scenery database files, there should be tall buildings in the
downtowns of major cities; those buildings should be in the correct
locations (in a lat/lon sense) and have the correct height.  They're
supposed to include everything above a certain height in the area, as
well as everything which is not necessarily above that height but
because of its placement poses a risk to aviation; but I have no doubt
they miss some in places like NYC where there are so many tall
buildings densely placed that one slightly smaller building surround
by taller ones doesn't seem that big a deal.

Yes, there are still several things missing.  One thing that's missing
as far as the buildings are concerned are unique models that actually
look like the buildings being represented (as opposed to the use of
generic box skyscrapers that are re-used frequently in a city like New
York or Chicago, are 500m tall and buried into the ground the
appropriate amount to make the above-ground portion the correct
height).  Such unique models come, slowly, when users make them and
contribute them to the database.  The three unique models currently in
the Chicago area scenery -- the Sears Tower, the John Hancock
building, and the Aon Tower -- were (I think) created and contributed
by Frederic Bouvier; he contributed them to the ground structure
database, and either Jon Stockill or Martin Spott removed the generic
buildings that previously had occupied that location.  So one way you
could make NYC look more like NYC is to start learning Blender or AC3D
or some other modelling program and start making good models for the
buildings.

The second thing that's missing as far as buildings are concerned are
the buildings which fill out the spaces in-between.  Some of those are
still fairly tall in places like NYC, and even the ones that aren't
are still important to making Manhattan look like Manhattan.  The FAA
DOF is no help here: what's in their data is in our scenery.  There
are, however, various websites that can help here.  For instance,
through Emporis' website, I'm able to get heights, either the four
bordering streets or an address, and an (unfortunately) copyrighted
picture for most of the tall buildings in NYC (I got bored paging
through them, arranged in descending order of height, after 1000 or
so).  That, plus the ability to go from street locations to lat/lon
that you can get from Mapquest/Google/Google Earth, can get you far
towards putting generics in the right locations; add in the artist
renderings on the Skyscraper page, and images from Google image
search, and you can replace the generics with buildings that look
right, too.

I saw your scenery email from a few weeks ago, but didn't respond
because I was ferociously busy, because most of your questions had
been answered many times in the mailing list archives, and because you
seemed at the time somewhat insulting of people that have put a lot of
hours into what we do have (absolutely it all has a very long way to
go; but everyone's trying when they have time, and you're very much
encouraged to jump in).  But one other thing that I suspect you're
thinking is wrong, but isn't, is building locations.  I remember you
commenting on the buildings in the East River, etc.  The issue here
isn't the building locations; there are error bars on the locations in
the FAA DOF, but they're not big in places like Manhattan.  When you
see buildings in the water, the problem is almost never that the
buildings are in the wrong place; the problem is that the *terrain* is
in the wrong place.  Go to some of those buildings in the East River
with the UFO; hover on them, then open the property browser and get
your precise lat/lon; then put that lat/lon into Google Maps or
Mapquest's map-by-latlon.  You'll find that you *should* be hovering
over land.  Hover on one of the container-loading cranes "offshore" of
the Port of Los Angeles and Long Beach, repeat this procedure, and
you'll find that you should be over the port according to the map.

The issue is the dataset currently used for coastlines and river
courses, which can be off by significant amounts.  To me, this is
something that needs fixing more than city building stuff does,
simply because it's more fundamental:  no matter how nice folks make
the buildings of Rosslyn and the monuments of DC look, they're going
to look bizarre sitting in the Potomac.  There are people working
right now on creating the infrastructure that allows people to
submit changes not just to coastlines and watercourses, but land
use information as well; search the flightgear-devel archives for
Ralf Gerlich and Martin Spott's posts on the landcover db, or just
head off to http://www.custom-scenery.org/?id=212 .  They've
used this infrastructure to produce some very nice, reasonably
accurate scenery for part of southern Germany (and in answer to your
other post, at least people here are aware of GRASS -- it's used in
this project).


> URL to the FAAs data?

Despite being public domain data, the FAA has not at present chosen
to distribute it on the web; you have to buy it with bunch of other
datasets collectively called "Digital Aeronautical Info".  I'm about
to buy another copy of it, provided no bureaucrat has made an
unfortunate decision about distribution like they did with the DAFIF;
if you want to look at it when I get it, or look at the old one I've
got, my understanding is that's fine.  But if what you really want
is building locations of the stuff in the DOF, those are the same as
the building locations in the FGFS scenery database, since that's
where that information came from; head off to http://fgfsdb.stockill.org/
to the Objects page, and filter the location list using "NY BLDG" in
the "Description" field.  You'll probably get some stuff in Buffalo
and Rochester and so on too, but that won't be too bad.


> How to convert to models? (I have still not "gotten into" Blender's
> UI--The ac format seems to be frame coordinants and a bitmap to lay on
> them.)

Almost everyone here uses either Blender or AC3D.  I use Blender;
Blender has very, very good tutorials out there in webland that helped
me a lot with the interface.  I understand it's a bit annoyoing to be
messing around with tutorials creating things that don't have anything
to do with what you want to make for FG; but it's time well spent.

-c


-- 
Chris Metzler                   [EMAIL PROTECTED]
                (remove "snip-me." to email)

"As a child I understood how to give; I have forgotten this grace since I
have become civilized." - Chief Luther Standing Bear

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