Re: [OpenMap Users] partially drawn map

Hi Leah,

There isn't a problem with the code, per se. You are seeing the
effects of looking at zoomed out CADRG images when you are at the CADRG
projection zone bounary. At certain latitudes (zone boundaries) the
pixel spacings for the images differ. You can see this by looking at
the relative pixel size of Korea in your images.

The CADRG images were designed to be viewed at certain scales, and
overlapping images are added to the tiles for each zone, so you
wouldn't notice the change as you pan north or south. When you zoom
out, though, those overlaps are revealed, and you are seeing the
effects of what happens when the map thinks that the upper zone should
be displayed. There was additional code added to the 4.6 release that
scaled images from other zones to fill in the different areas, but at
certain scales it doesn't always kick in, but it's better than it used
to be.

So, that's what's happening. For GNC charts, the base scale is
1:5,000,000. If you zoom in closer to that, you'll notice you won't
see that gap.

- Don

On Jun 15, 2004, at 7:58 PM, Leah Wong wrote:

> Hi Don,
>
> I took your advice and upgraded to OpenMap 4.6. I haven't gotten any
> more
> of those OutOfMemoryErrors when zooming in/out. However, there is the
> performance issue when loading CADRG data that I'm delighted to see
> you are
> fixing in the maintenance patch, and one more issue that I saw on
> v4.5.4
> that is still around.
>
> I'm not sure the list supports attachments, so I've included
> hyperlinks to
> some screen shots illustrating what it looks like when OpenMap
> partially
> draws the map. To create this problem I panned around a map, in this
> case
> over Korea. In this screenshot-
> http://users.adelphia.net/~leahwong/images/openmap/half.drawn.jpg
> -you'll
> see how the map doesn't fully draw. Next, I panned down a little bit
> more,
> and the map fully draws-
> http://users.adelphia.net/~leahwong/images/openmap/fully.drawn.jpg.
> Any
> idea what is causing this? Maybe the frame cache isn't pulling in
> enough
> frames? Maybe there's a property file setting for me to adjust?
>
> Thanks as always,
> Leah
>
>
>
> --
> [To unsubscribe to this list send an email to "majdart@bbn.com"
> with the following text in the BODY of the message "unsubscribe
> openmap-users"]
>
>

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Don Dietrick, dietrick@bbn.com
BBN Technologies, Cambridge, MA
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=

--
[To unsubscribe to this list send an email to "majdart@bbn.com"
with the following text in the BODY of the message "unsubscribe openmap-users"]