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| Subject: | Re: [gislist] Van Der Grinten, countries, lat/long data, Flash,
issues... |
| Date: |
05/24/2004 06:25:01 PM |
| From: |
FB` |
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|
On Monday, May 24, 2004 at 4:28 PM, Brian Russo wrote:
> At Mon, May 24, 2004 at 03:27:20PM -0400, FB` wrote:
> > Hi,
> >
> > Quite a kitchen-sink issue here, but any light shed on any part of
> > this would be immensely helpful - please keep in mind that
> > cartographically, I know very little, so what may seem obvious to
you
> > here might have completely escaped me.
> >
> > I'm developing a (seemingly) simple Flash-based map navigation
tool,
> > (slightly more complex than the one shown at
> > http://www.computerlove.net, but with a similar basic function)
and am
> > facing the following issues, some of which I feel certain can be
> > solved with the right kind of data/approach:
> >
> > An original world map to start with, which is a Van Der Grinten
> > projection in Illustrator format, with some cropping, the
specifics of
> > which we know absolutely nothing about.
>
> What software do you have to work with as far as stuff that handles
> georeferenced data?
I've done some noodling around with, and feel comfortable "enough"
with GMT (http://gmt.soest.hawaii.edu/)
I have also been pointed in the direction of TerraGear
(http://terragear.org/) but have not had a chance to play with it.
> And what scale are you aiming for?
This is a difficult question, as I'm not quite sure what the max zoom
I'm looking for translates to, but figure at the maximum magnification
I have in mind,
> > This file is too detailed to use effectively in Flash - so the
> > original issue is locating a reasonable substitute. We have
discussed
> > rolling our own from USGS data, but it seems like quite a long way
to
> > go for a simple map...
> >
> > However, the original vdg projection should be retained if at all
> > possible, for its appearance.
> >
> > Then, I have a list of ~500 cities I need to plot on this map -
and a
> > reasonably good approach currently for determining the lat/long of
> > each city (have much larger file, extract names as they appear in
> > selected list, manually select from multiples)
> >
> > However, knowing as little as I do about the present map, the next
> > problem presents itself: plotting those points on the map - I have
> > thus far been unsuccessful in locating working code/formula to use
for
> > lat/long->vdg projection - so this is the first real need - if you
> > know this, or can point me at a resource that explains it, please
let
> > me know.
>
> Use either GIS software or something like NIMA GeoTrans to convert.
I have been unable to get GMT to output sets of x/y coordinates on the
hypothetical vdg map.
If the formulas are available and I can get them to work, this becomes
moot, as I can then do the transformation in PHP or even ActionScript
in flash.
> > The next problem is that of country names and leads into other
> > country-related issues - the spec calls for country names to be
shown
> > within each country at a specific magnification - so I would need
to
> > be able to track down some data regarding the position of the
center
> > of gravity (so to speak) of each country... If this type of data
> > exists... Additionally, a click-to-zoom-to-country functionality
is
> > desired, and for this, I figure data regarding the
N,E,S,W-ern-most
> > point in each country would be useful... otherwise, I'd have to
enter
> > coordinates/mag settings by hand...
>
> Centroid of the polygon (more often actually the bounding rectangle)
> should work ok in most cases.. manually adjust when it doesn't.
Ah, was not even aware of the term, but that should do nicely. Do you
know where I could find information on extracting this data from the
source at hand?
> > Due to budget constraints, I can only really look into GPL/PD
> > solutions to this problem - to that end, I have been browsing the
GMT
> > documentation, but nothing has jumped out just yet...
>
> Mapserver is probably more useful than GMT here.. GMT is more useful
for
> gridded than vector data..
I will have to look into it - I came across it in looking around
earlier but didn't stop long enough to get a really good idea for what
and how it did.
I've also had vmap0 (http://www.mapability.com/info/vmap0_index.html)
suggested to me as a source of vector information...
The main concern that someone brought up is the political freshness of
the country data - the coastlines I have played with in GMT do not
have this info, and doubt was cast on the freshness of the USGS 30''
data...
> - bri
> > FB`
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