[Xastir] strangeness drawing GNIS maps?

[Curt Mills]

On Wed, 19 Jan 2005, Jason Winningham wrote:

> I noticed that, even when viewing a very small area (zoom 16) xastir will
> "draw" several states worth of GNIS data every time.

> Even though I'm zoomed in on a very small area in Alabama, it seems to draw
> maps for AK, IL, IN, TN, etc etc.  The map is actually drawn correctly, the
> problem is the CPU time involved in not drawing all those maps.
> 
> Maybe there's a problem with the data?
> 
> What are the values in map_index.sys?

The important values for this discussion are the
top/bottom/left/right edges of the map data.  Those extents get
stored into the map_index.sys file.  If you have some errant values
in there, Xastir will think the map might cover the area in question
and run through the map attempting to find them.

You might try reindexing those maps to see if that helps.  Perhaps
you got some bad extents in there.  The extents are in the Xastir
coordinate system:  Units of 1/100's of a second, lat/long.  Origin
is at upper left and numbers proceed in a positive direction east
and south.  You can look at some of the comment blocks in maps.c to
find out how that coordinate system works.  It's what I do each
time.  Line 448 is a good place to look.

-- 
Curt, WE7U.				archer at eskimo dot com
http://www.eskimo.com/~archer
  Lotto:  A tax on people who are bad at math. - unknown
Windows:  Microsoft's tax on computer illiterates. - WE7U.
The world DOES revolve around me:  I picked the coordinate system!"