On Fri, Mar 21, 2008 at 11:00 AM, AnMaster wrote:
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> It does indeed look like 0.9.8 had best coast line. Why is it so much
> worse in more recent
> scenery? Wouldn't it be possible to get the same good coastline as in
> 0.9.8?
As with anything, it's not quite that simple. The GHSSH coastline database
(used in 0.9.8) is indeed more accurate for ocean coastlines. However, for
any inland fresh water, it is much worse/less detailed than vmap0. So in
0.9.8 we used GHSSH for coastlines and VMAP0 for lakes & rivers.
However, we found that there were major discrepancies between the two
databases. For instance, lake washington near seattle is classified as lake
by GHSSH and ocean by vmap0, so it simply did not appear in 0.9.8.
Similarly there were things that were classified as ocean by GHSSH and lake
by vmap0 so they were both drawn on top of each other.
The decision was made to go with vmap0 entirely. We gave up accuracy around
the coast lines, but we gained a much more consistent picture of the world
... with no major missing bits and no overlapping sections.
Originally we only used GHSSH defined waterways, but this let to major
problems, like the great lakes only being half defined (i.e. the canadian
side of the lakes was not mapped so there was only land there.) And
strangely, some Canadian's complained about that! :-) So we went to the
mixed GHSSH-Ocean/VMAP0-fresh-water scheme, but people complained about the
missing water that fell in the gaps between both dataset classifications.
So then we went to vmap0, but now people are complaining about less detailed
coast lines!
What combination should we try next? :-)
Regards,
Curt.
--
Curtis Olson: http://baron.flightgear.org/~curt/
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