On Wed, Jan 14, 2009 at 12:23 PM, Martin Spott <martin.sp...@mgras.net>wrote:
> I'm quite aware of these implications - this is what I've been pulling
> together into the "due to the corresponding landuse data"- phrase. It's
> not only about freshwater, basically this affects any sort of ground
> coverage that is meant to match the coastline.
>
> <OFF TOPIC>: As (probably just a) few of you know I've started
> planning, installing and improving the required infrastructure to
> store, visualize, compare, merge and edit different datasets four or
> five years before now (even before OSM got public ....). I've also been
> inspecting numerous datasets (including several coastlines),
> investigating methods for editing the data remotely and spending quite
> a lot of time on other involved stuff.
> In "FlightGear slang" (TM) I'm therefore to be considered as being a
> "mere lurker" :-))) </OFF TOPIC>
>
> Even though I've been advertizing this side project occasionally, it
> has seen just very limited attention and support from other FlightGear
> fellows (I know that I'm bad at advertizing ;-))
> Every time I've been gathering for support, people typically fell back
> into silence (the usual procedure) .... and as long as the few
> involved people have to do _everything_ themselves, things proceed
> still steadily, but slowly. If there were some fellows ready to jump
> into this effort without asking for a readily usuable graphical
> interface unless they move their little finger, we could already have
> VMap0 landuse and GSHHS (or whichever) coastline merged together.
>
> BUT, the story about merging vector data is still not right on topic.
> Your response lacks an explanation why you consider it as being
> impractical to blend the bathymetry data against the coastline in the
> same manner as we're currently dealing with the SRTM elevation grid.
I thought I fully explained what I thought was the biggest potential
difficulties with your approach:
(1) SRTM data has +/- 5 to 10 meter error built in. In land regions with a
very flat slope leading up to the coastline that can lead to things like
hundreds of meters of coast line inaccuracy, or very odd artifacts and very
unnatural boundaries. How about the Dead Sea or Death Valley?
(2) I think it will be very easy for entire regions to get put under water
if there are small errors in terrain elevation or small errors in tide
computation.
> Sorry, didn't mean to press the wrong button here, but just wanted to
> > provide some realistic feedback.
>
> No, you didn't push the wrong button, you've simply trying to discredit
> my effort and ideas without proper evaluation.
Errrr, if that's what you think, I guess I'm not going to be able to talk
you out of it. In actuality, it is my engineering brain looking for the
biggest challenges first and vocalizeing them. If you can get over the
biggest humps then the rest of the journey is down hill. Again, I'm sorry
if you didn't read it that way. If you think I'm trying to "discredit" your
ideas here, then you are simply way way way off, and that I can't do much
about.
Curt.
--
Curtis Olson: http://baron.flightgear.org/~curt/
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