[Xastir] Terraserver problems with map registration

[Bob Donnell]

I was discussing this with Curt on IM, and had the thought that once the
absolute limits are known, that the code performing terraserver requests
should evaluate the window size xastir's running in, then form a sub-scale
request appropriately and then upscale the returned image after the fact
Most of us with high resolution displays wouldn't often notice if the image
request was scaled to 50% then the returned image was scaled to 200%.  If
the window is more than 3 times the limit, do it to 1/3 and 3x scaling, etc.
So the idea is to downscale the requests to something terraserver will
reliably return all of, and then upscale it on the local PC.  I guess the
main idea is that by scaling our requests, we control how much complexity is
involved in rescaling the returned image.  So integer amounts and even
percentages, like 40%, 50%, 75%, 80%, etc. reduces a lot of the scaling
tasks to simple integer math.

Besides, anyone running that big a screen must have cycles to burn <grin>

It also occurs to me that this might be a file size limit, vs. a pixel count
limit, so the returned image size may be related to that - though from their
end, it'd be a lot easier to code a pixel count limit.  If file size was the
limit, then the file size could vary due to compression factors and how much
detail is present.

73, Bob, KD7NM

-----Original Message-----
From: xastir-bounces at xastir.org [mailto:xastir-bounces at xastir.org] On Behalf
Of Tom Russo
Sent: Wednesday, November 28, 2007 10:36 AM
To: Curt, WE7U
Cc: Xastir at xastir.org
Subject: Re: [Xastir] Terraserver problems with map registration

On Wed, Nov 28, 2007 at 10:31:57AM -0800, we recorded a bogon-computron
collision of the <archer at eskimo.com> flavor, containing:
> On Wed, 28 Nov 2007, Curt, WE7U wrote:
> 
> > On Wed, 28 Nov 2007, Curt, WE7U wrote:
> >
> > > At 1410x950 it looks ok.  If I go much bigger in either direction 
> > > the registration gets knocked out of whack in the E/W direction.
> >
> > Looks like 1410x992 is the limit.  Go over that by one pixel in 
> > either direction and it's off.
> 
> Hmmm.  Can go up to 1408x1109 and it's fine too.  Must be larger 
> vertically before it can go larger horizontally?

The issue is entirely that the file requested is too large for terraserver
to agree to serve.  It is likely not a fixed pixel limit, since jpg
compression probably allows some pizel-wise larger images to be smaller
byte-wise than others.

-- 
Tom Russo    KM5VY   SAR502   DM64ux          http://www.swcp.com/~russo/
Tijeras, NM  QRPL#1592 K2#398  SOC#236 AHTB#1
http://kevan.org/brain.cgi?DDTNM "And, isn't sanity really just a one-trick
pony anyway? I mean all you get is  one trick, rational thinking, but when
you're good and crazy, oooh, oooh,  oooh, the sky is the limit!"  --- The
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