[ gpsdrive ] gpsdrive and NOAA charts

Chris H chris123 at magma.ca
Sat May 10 18:24:43 AKDT 2008


Currently playing with gpsdrive for marine application (ie: for use on my 
sailboat) This is really interesting and fun stuff. Ive been following 
Hamish's outline available here:

ive created a series of tiles from a test NOAA map.

Where i get stuck is with the map importing assistance. I'm using a large 
scale map that has been converted to a series of tiles ( approx 200 ). When I 
try to import the map tiles the assistance asks the following questions:

screen x
screen y

Note: I'm importing maps this with no gps connected. 

So two questions. 

1. Where do I get these coordinates from and are they required for each tile.
2. Is there a method whereby this process can be automated say by importing 
the original large scale map and then somehow having gpsdrive recognize that 
the following set of tiles belong to that specific map and associated set of 

Once I get this sorted I would like to write a tutorial on this with the 
assistance of others of course as this is a wonderfull way to use gpsdrive 
with raster charts. There are only a few functions missing to have a workable 
marine navigation/plotting solution with gpsdrive but that's another story 
for another post and feature request. 

The one bug I noticed is with the screen redraw when any of the screen 
respositioning functions are called from the assistant. I'm not sure if this 
is a memory limitation on the local machine or an actual bug. I'm thinking 
the former as the memory is quite low. 

Once I get his sorted then I would like to make a complete collection of the 
Great Lakes and the Eastern Seaboard of the Canada and the US, basically the 
preferred sailing area as I have purchased a complete set of NOAA charts on 

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