[ gpsdrive ] Landsat downloads

[Hamish]

Hi,

I have just fixed the (new) in-program Landsat download scaling code to
use correct math instead of a (AFAICT) fudge factor which would only
soft of be right at a single latitude.

Tested with some old GPX track logs, it all finally lines up. woo hoo!

The bad news is that all your old downloaded landsat images are probably
junk; the good news is that from now on newly downloaded maps should be
ok. The new download tool that Guenther recently added is really
excellent and easy to use. (wish: ability to pan without leaving tool?)
(yellow is already downloaded, green is current selection)

The equivalent scaling code in gpsfetchmap.pl still needs to be fixed--
I don't know anything about perl: is cos() a standard function? how
about PI?


I also made it easier in the code to change the WMS server- you should be
able to drop in any other WMS server URL &/or layers and have it work.
e.g. we're requesting Landsat, but the OnEarth server can deliver
lots of other layers too: http://onearth.jpl.nasa.gov/
Or maybe your local government hosts WMS aerial photography?
Or maybe you want to try NOAA's WMS nautical chart download? (mmmph)
... Something to make user-configurable in the future.

I notice if the server is overloaded you get a small 300 byte XML error
message, but that is saved to .jpg and map_koord.txt anyway.  how to
catch that? From experience with working on WMS downloads for other
software I have found that the error mode is in no way standard and
rather hard to test for across diff't flavours of servers.


enjoy,
Hamish