[ gpsdrive ] noaa charts 11466_1

[Hamish]

Chris:
> Wow...now that's a tutorial..;)

I struggled with that for a long while, especially the COMPRESS segfault.


another tip for QGIS- load multiple sections with:
  qgis 11466_1.tif 11466_3.tif 11466_2.tif
(order counts)

and then zoom to layer 2, and set the transparency for it to 25% or so,
that way you can see how well things lined up. It appears that the
coastlines are sometimes a bit off, but things like rocks and beacons
are more strictly controlled.

and as always, beware when creating new waypoints from within GpsDrive,
the map scaling is often only approximate. (ie google/expedia map scaling
are just near-guesses not exact calculations)

Creating them in QGIS from the GeoTiff should be pretty good.
Layer-> New Vector Layer->Points, whatever attributes you want,
right click on new layer name in the left-side legend, "Allow editing",
select the "capture point" button from the icon/ribbon toolbar, click
on map to create waypoints. once done digitizing points untick "Allow
editing" in layer properties, and save the shapefile.

Enable the GPS plugin, then Plugins->GPS->Create new GPX layer and
save as filename.gpx.

Even though there is a Import->GPX waypoint menu item, support in gpsdrive
is not yet finished. So you'll have to use gpsbabel to convert GPX wpts to
a way-*.txt gpsdrive format file, as detailed on the Driving Directions
wiki page.

It is more work but much more exact. I think it is better that the
waypoints match the GPS position rather than what you see drawn on the
GpsDrive tile (e.g. during fog, nighttime). While hopefully there is not
much difference between the two, but be aware that there can be.
(due to scaling factor/method; projection; convergence angle; ...)

my highest priority is to get the OSM download tiles correctly registered.
for that I think I need to find/see their server code for zoom level.
Landsat maps from the download tool are now good.

> Will archive this data on the wiki once tested at this end.

thanks,


Hamish