[mkgmap-dev] Etrex sea floods tile unless well zoomed out

Mon Mar 1 17:57:36 GMT 2010

On 01.03.2010 17:02, Mark Burton wrote:
> I just noticed on my etrex that tiles that touch the coastline are
> flooded when zoomed in less than about 30Km. Neither mapsource or the
> nuvi show the same problem with the same map (this is with
> --generate-sea=polygons). When zoomed out, the coastline looks fine.
>
> Anyone else seen this? got a fix?
>
> Mark
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>    
I don't have any probs (at least when simply looking at the map), not 
tried with actual GPS reception or demo mode, but with GPS off. I can't 
believe that there are any differences though.

Here's my take:
Tiles with sea inside: When zooming around, then often in the rendering 
process, blue intermittently flashes up, before normal map is drawn. I 
will experiment a bit, to find out why no yellow flashes.
Tiles with no sea inside: Sometimes yellow background flashes up on map 
panning. I assume this is because the map has no 0x4b background (I use 
--transparent, but make maps opaque with gmt.exe after creation).

This means:
a) either your typfile has draw priority for land not higher than sea 
(remember that GPS draws opposite order from mapsource on same DP).
b) typfile is not correctly associated to map.
You should try to set some really strange colors for roads inside 
typfile to verify that typfile is actually used.

If you can rule out a) and b), then try --transparent on map creation, 
but afterwards making maps opaque with gmaptool and see if there is any 
difference (though there should not be one).