[ gpsdrive ] gpsdrive and NOAA charts

[Chris H]

On Saturday 10 May 2008 22:59:14 Hamish wrote:
On Saturday 10 May 2008 22:59:14 Hamish wrote:

>
> the gdal_slice.sh script produces a text file (map_koord_draft.txt) with
> registration info for each tile. merge that into ~/.gpsdrive/map_koord.txt,
> then it is all done for you. no need to bother with the map import tool.

OK...this is great. I figured there had to be something to index the files. 
Just did no know where to look. TKS.... 

> ("gdalinfo" on the .tif output tiles will give you the corner coords if you
> really want them, but you shouldn't have to go through that trouble)

right.

> > 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 coordinates.
>
> that's what gdal_slice.sh does. move each set of tiles into its own
> subdirectory if you like to avoid clutter.

Two things come to mind here. (1) how does that impact the map_koord.txt file. 
In other words does the path need to be identified?  (2) naming conventions; 
wondering what would be better/simpler or conventional, the actual chart 
name; ie: Cape Hateras to Cape May or the NOAA chart number; 1300_1. 
Personally I would preferr the chart name as that seems simpler.

> > 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.
>
> please improve here:
>  http://grass.osgeo.org/wiki/Export_for_GpsDrive#Using_gdal_slice.sh

Yes I read that. Not sure if this applies to gpsdrive issues but here goes. If 
its considered off topic, just let me know. 

For some reason using gdal to convert the NOAA charts did not work for me. 
(discussion for a later date as gpsd is also not working on this Kubuntu 8.04 
install as it cant bind to the port....but that's a different issue that a 
rebuild system should cover at a later date)  

So I used the following: NOAA Chart Reprojector which is also scriptable and 
comes with a gui for those inclined to convert to tiff. 

http://www.csc.noaa.gov/crs/chartreproj.html (linux, mac, windows)

What I noticed is that NOAA charts come is four projections for some reason 
(Mercator, Transverse Mercator, Polyconic, Lambert Conformal Conic) Now since 
Im a nube at this, I was wondering if the chart's projection setting is an 
issue for converting to tiff and use in gpsdrive or if I can just script it 
to the desired projection and let it run on all the charts.  If not, then 
this implies that each chart must be read individually reviewed and converted 
to the preferred projection That would be incredibly time consuming. 

> Hamish
>
>
> ps- don't blame me if you hit a rock

-- 
/ch