Subject:
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Re: New World LUG Map demo
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Newsgroups:
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lugnet.admin.general
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Date:
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Fri, 28 Mar 2003 05:00:33 GMT
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Viewed:
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193 times
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Many years ago (maybe 1986) I wrote some of the simple projection routines for
a little mapping project.. I think it was some sort of independent study.
While I was unaware of the Free BSD and linux issues, I wasn't intending to
propose ArcView due to the issue of access to it of course. It is a bit on the
pricey side these days too, in the event you don't have ready access to use it.
I was mentioning it mainly because 1) you mentioned the different projection
idea and ArcView handles that well. 2) With SVGMapper it generates the SVG for
you but in a way that uses XML and javascript to leave it wide open to
customization. I thought if you were familiar with that (svgmapper) you might
glean more ideas. 3) It even has routines built in (svgmapper) for generalizing
features. [arcview does too].
If you were willing to make the base maps fairly static you would have your
code handle all the other stuff, sort of post-process on the svg files.
If you look at that sample page I posted there is a 'map tips' thing down in
the lower right It doesn't work well with overlapping symbols though.
If it would be helpful I could send you these files and you could see how these
guys approach it. Just a thought. Not intending to side track you or anything.
I think it's pretty zoomy.
In lugnet.admin.general, Todd Lehman writes:
> In lugnet.admin.general, Ken Koleda writes:
> > A few questions and comments.
> > - What is your source for the country polygons?
>
> A public domain ESRI .e00 file from GRID or NOAA, I forget which.
>
> > - You are coding all the map generation? You have your own code writing
> > the SVG?
>
> ya
>
> > I have been recently working with a program called SVGMapper. Well, it's
> > an extension really.. an extension to ArcView from ESRI.
> > Here is a test sample:
> > http://rougeriver.com/svgmaps/cso_comp/map.htm
> > While this doesn't look much like what you have, it may give you some ideas.
>
> I realize how popular ArcView is, but I avoided it because I need things to
> run on Linux and FreeBSD (and also because of licensing issues, since it's
> a commercial product). I also needed low-level ASCII representations of the
> polygons if I was to have any hope of understanding and customizing what was
> going on. So I searched and searched and eventually found a public domain
> dataset in a format that I was able to transmogrify into something usable for
> my purposes.
>
> > Also, the program that generates the SVG has an option, which I've used,
> > to compress the files. It uses (freeware?) called gzip. One hassle is
> > that the .SVGs are no longer readable text. But, with my data sets the
> > files go down by about 2/3rds in size. Helpful for folks on dialups.
>
> Ya I'm piping all the SVG data through gzip -9 and writing out .svgz files
> to the SVG output cache and seeing about 5.7x compression on average.
>
> > - Some where on there you should have the instructions on how to zoom, pan
> > etc,
>
> Good idea...although before encouraging zooming in, there probably needs to
> be a way to force an overly detailed map (with the default being as it is
> currently, which is to include _just enough_ detail for the intended view).
> Right now, if you zoom way in on a full-world image, you'll see really low-
> resolution polygons, whereas if you generating a map that's specially zoomed
> in from the start, it uses higher resolution data. This is simply to reduce
> bandwidth as much as possible. The full world view at full resolution is
> more than a megabyte even after gzip compression, making it unsuitable for
> a general entry page.
>
> > "zoom = control+left mouse" for example
>
> I'd hate to Mac OS X users to Ctrl-click or Windows users to press Command-
> click. Maybe it could guess what hardware they're running on from the user-
> agent string their browser sends. :)
>
> --Todd
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Message is in Reply To:
 | | Re: New World LUG Map demo
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| (...) A public domain ESRI .e00 file from GRID or NOAA, I forget which. (...) ya (...) I realize how popular ArcView is, but I avoided it because I need things to run on Linux and FreeBSD (and also because of licensing issues, since it's a (...) (22 years ago, 28-Mar-03, to lugnet.admin.general)
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