[Xastir] saving tigermaps server maps?

[Gerry Creager]

Using JPEGs is sometimes problemmatic.  Using a raster image requires 
some way to register it (find enough points where you know the 
coordinates to match up the raster image [jpg] and vector maps [tiger]) 
and rectification (warping said image so that coordinates match between 
the datasets).

Someone correct me if I'm wrong, but I believe we're using 2 points to 
register and not doing much beyond rubber-sheet stretching to rectify an 
image over a vector dataset.

In the normal GIS world, registration is done by an affine method, and 
one wants a minimum of 3 points of control.  Similarly, rectification 
usually requires 5-7 control points (with any more than 7 starting to 
cause problems...).

That's not to say overlaying an image is too difficult.  That's what 
we're doing with the radar composite I've been providing.  It's 
available as a gif, png, jpg or tif (for the bandwidth rich among us) 
and the .geo has been crafted those image resolutions and not lose much 
in radar data bin resolution.

Gerry

Orrin Winton wrote:
> Yes, i've been downloading those files, but i also
> want to be able to make xastir maps out of .jpg files
> (if jpg is a Linux-compatible format).  If it's not 
> too difficult.
> 
> orrin
> 
>  
> --
> 
> --------- Original Message ---------
> 
> DATE: Sat, 27 Sep 2003 18:05:40
> From: "James Cour" <K1ZC at comcast.net>
> To: <oakenshieldd at lycos.com>,<xastir at xastir.org>
> Cc: 
> 
> 
>>Orrin,
>>
>>Why not just download the Tiger layers you need for the counties you need?
>>A visit to this site should fix you up:
>>
>>http://arcdata.esri.com/data/tiger2000/tiger_download.cfm
>>
>>
>>
>>
>>
>>Download the info you need, drop it into a folder under your
>>/usr/local/share/maps directory, and then reindex your maps.  Xastir will
>>figure out the rest, and you can set some options on Map Chooser to decide
>>what to display.
>>
>>Jim
>>
>>
> 
> 
> 
> 
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