[ka-Map-users] Is there any way to show a lot of moving gps?

[Tim Schaub]

> > tile_source=nocache
> >
> > is it right?

If you use

METADATA
	"tile_source" "nocache"
END

then your tiles will get rendered by the tile_nocache.php script.  This script does a couple things differently than tile.php: it doesn't draw a big metatile (though it does do some buffering of the tile), and it doesn't check your cache to see whether the tile already exists (or write the new tile to the cache).

A drawback of not drawing a big metatile is that labels may be repeated more frequently than you'd like.  Another one is that if you have a really big symbol near the edge of a tile, it may be truncated (and not symbolized on the neighboring tile).  For this, there is a $tileBuffer that is set in tile_nocache.php (this is probably not the best place for this to live).  The $tileBuffer will create an extra bit around each tile that is trimmed off - the value should be set to half of your largest symbol size in pixels.

A benefit of using tile_nocache.php is that you can use variable substitution if you'd like.
http://mapserver.gis.umn.edu/docs/reference/mapfile/variable_sub
This requires adding in variable names to your mapfile (see doc above) and then setting values for those variables on the client side.  If this has nothing to do with what you want, ignore it.  If you do want to take advantage of it, I can give some more detail on how to do it.

Tim