[Xastir] Re: Bounding boxes

[Curt Mills, WE7U]

On Tue, 14 Oct 2003, Tom Russo wrote:

> Actually,  I think the paper maps *are* distorted, too --- they are UTM
> projections of a 7.5' lat/lon band, and that's what the collar info
> even says.  I'm looking at a USGS paper quad right now, and seeing in the
> bottom left corner that it states "Projection and blue 1000-meter ticks:
> Universal Transverse Mercator."  It's not just the DRGs that have been
> projected into UTM, it's the original source map.

I'll have to break into my gear and take another look at the paper
maps.  It's also possible that they've changed their projection over
the years, but I don't think so.


> You're right, of course, the DRGs are distorted, and I'm just too used to
> looking at maps from the area I'm in, where the quads are still *roughly*
> rectangular.  Go farther north than where I live and these effects are more
> noticable.

Here north of Seattle it's quite noticeable.


> I believe that the only real difference between the paper maps and the
> DRGs is that they've been rotated  --- the paper maps are made so the
> N/S neatlines are as parallel to the edge of the paper as they can be,
> whereas the DRGs are rotated so the UTM grid is parallel to the pixel grid.

I'll take your word for it.  I've had more experience with the DRG's
now than I have with the paper maps.  I know my hunting area so well
that I often don't break out the USGS quads that I carry each year.
It helps that I have a hundred or so waypoints in the area stored in
the GPS I suppose.

-- 
Curt Mills, WE7U                    hacker_NO_SPAM_ at tc.fluke.com
Senior Methods Engineer/SysAdmin
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