[Xastir] data in .fgd file for geotiff map

[Chris Bell]

> 
> I'm using FAA sectionals from
>   http://aviationtoolbox.org/raw_data/FAA_sectionals/current/
> which are (rather large) GeoTiff files.  I have them as maps to
> xastir, and the longitude seems to be right on, but the latitude
> seems to be about 1.4 minutes off.

I have not looked at the files yet, (low on disk space at the moment)
but I looked at the web page.  My guess would be that it is not
placing it right since it is not clipping the borders. (Is there more
collar data on one side than the other?  Top and bottom about the
same?)

> 
> The site these are from has a .tfw file (for each .tif file)
> that contains
>   63.753925000000002
>   0.0
>   0.0
>   -63.753925000000002
>   -378078.33973611565
>   -18298.274814258024
> (there are no .fgd files at the site).  Can this be converted to
> the .fgd file?

Currently, we do not use this file.  

> 
> It looks nothing like what mapfgd.pl produced for the map, which
> is
>   1.5.1.1   WEST BOUNDING COORDINATE:  0.000000
>   1.5.1.2   EAST BOUNDING COORDINATE:  0.125000
>   1.5.1.3   NORTH BOUNDING COORDINATE:  0.000000
>   1.5.1.4   SOUTH BOUNDING COORDINATE:  -0.125000
> so I suppose it is something in this file that is incorrect.
> 

Yes, those numbers are very wrong. That script needs to have the map
files named using the USGS DRG conventions, so it cannot really be
used for these.  However, it looks like the .htm file is the .fgd file
converted to pretty html.  You can get the bounding coordinate values
from it, and fix those four lines.  (that is all we need)

> Or, is there some number I can copy out of the listgeo output to
> put into the .fgd file?
> 
> Also, the chart legend and borders appear in the xastir window,
> I suppose I'll need to get rid of those also.
> 

The proper .fgd file should fix that. 

Let us know if that helps!  

Chris.
KD6ZWR