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Subject: Re: [Nml] Cap'n tips
From: Steven D. Tripp (tripp@XXX.XXX)
Date: Sun Feb 14 1999 - 21:37:01 EST
Rick Emerson wrote:
>
>
> One quirk I did see repeatedly is a loss of centering when using
> "intellegent zooming". This feature which is very useful keeps
> selecting the most appropriate scale chart for the area being
> displayed. If, for example, you're looking at a 1:40000 chart and
> want to zoom down to get a close look at a feature and a 1:20000 chart
> covers the area, this chart is brought up automatically. Conversely,
> zooming out will invoke the next smaller scale chart (e.g., 1:80000).
> When zooming in, however, occasionally the center of the new, larger
> scale (smaller area) chart is no longer anywhere near the center used
> with the previous chart. I was looking at the Portland, ME area and
> zoomed in to look at Peaks I but found myself looking at a spot well
> to the southwest of there. I'm not sure *why* this happens and will
> accept it may well be an error on my part but it can be frustrating on
> occasion.
I'm not sure how the Cap'n works, but some of these nav programs do raster maps
in this way: They break up maps into small rectangles for storage and load
several (9?) pieces and join them seamlessly on screen. When you zoom in or
out, it takes the clickpoint and tries to find a rectangle at the higher or
lower scale and then loads it at the center and loads its surrounding pieces.
If your click occurs right on an (invisible) boundary the computer won't know
which rectangle to load to the center. On the other hand maybe the programmer
made a mistake in labeling the rectangles.
Incidently, I am rewriting my Mac navigation program for Windows and UNIX and
would be interested in suggestions for features.
> --
Steven D. Tripp +-------------------------------------------+
University of Aizu |+-----------------------------------------+|
Aizu-Wakamatsu, Japan || Lat 39.5 N Long 140 E GMT +9 ||
tripp@XXX.XXX |+-----------------------------------------+|
fax +81-242-37-2599 +-------------------------------------------+
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