A really weird problem with querying a map

[Gregor Mosheh]

Fawcett, David wrote:
> I ran into something with 5.0 and didn't think that much of it.  If you
> haven't defined a TOLERANCE and TOLERANCEUNITS.  Try a tolerance of 1
> meter or something like that.  

Well, this is something...

Of note: The data layers are in geographic with NAD27 (EPSG:4269), 
whereas the map's output projection is UTM zone 9 NAD 27 (EPSG:26709). 
Evidently this is very relevant when it comes to queries.

I set these:
   TOLERANCE 100
   TOLERANCEUNITS pixels
and it works well enough to do the job.
But not well enough for me to understand what's happening.

I do find this odd. The documentation says that the defaults for polygon 
layers are "0 pixels" meaning that one must click inside the polygon. 
This would be just perfect, but instead I get "nothing found" if I leave 
it at that default.

I find it odd that I should have to use such a huge tolerance, too. If I 
reduce the tolerance, I start getting all sorts of false positives: 
clicking too close to a border will bring up the neighbor's info. I find 
that confusing: I'd think that to be a side effect of a *higher* 
tolerance being set, yes?

-- 
Gregor Mosheh / Greg Allensworth
System Administrator, HostGIS cartographic development & hosting services
http://www.HostGIS.com/

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