[mapserver-users] classitem and class values affect display of map?

[woodbri at swoodbridge.com]

On 30 Jul 2002 at 13:28, Patrick Stanistreet wrote:

> I have been working with the itasca demo trying to learn mapserver and gis.
> 
> I have simplified the demo.map file to a single layer which displays just
> a  colored in state outline.  The layer is ctybdpy2.
> 
> I would have guessed that I could change the class value to another city 
> but when
> I do that the map does not display.  Going back to itasca work fine.

It is likely that you are having a probalem with extents. This is a 
common problem for people just starting with mapserver. The itasca 
demo has the extents od the map defined in the mapfile, if you change 
the shape file to another one that has different extents but have not 
changed the extents and possibly the UNITS for the mapfile to 
coinside with the new shape file then mapserver will just display the 
old extents and since you new shape file does not overlay those 
extents it will not show anything, but a blank image.

-Steve W.

> 
> Perhaps a pointer to why this occurs , I would be glad to read any
> further documentation or pickup a recommended book that would
> explain what is going on here.
> 
> 
>